Electronic Repair Questions/Answers & Testimonials- Part 36

By on July 26, 2009

Thank`s for the tips,i`ll already check my lcd power board and found 2 diod
(3 pins)was damaged and 1 6pins power regulator was damaged.
The first thing i do is replace the 2 diod and connect the power it works
but just for 15min only then the problem start again.
Can you give me the way that i can solve the problem.


Hi Zul,

Check for corresponding components in the circuit too especially components in the power side





I found your website to be very useful. But i have a problem.I am tried to repair benq Fp71g+ lcd monitor. It was blank and could not see anything. I repalced two c5707 (with the same part), one pico fuse, one 0.22 cap (i saw the bubble on the side), and now, only 2 of the 4 ccfl are working, and the monitor turns on for 1 sec and then turn off. i checked and saw Q812 is not good. I dont have it yet, but i removed it for now. I think when i will replace it the 2 other ccfl will work ok too. Is this correct? And what can be the reason that the monitor is on for one sec and then off?? I could not find anything…

Please help me…


Hi Roee,
Normally it could be the bad backlight or faulty inverter board. I suggest that you compare the resistance of the components between the two circuits (top and bottom lamp circuit). Any different in resistance value would be a sign of failure in that particular circuit. Hope this helps!





Henry Wilson
Message: Dear Jestine: I enjoy your email repair updates. I especially enjoyed the photos and video of China. Looks just like an American city only cleaner. I also appreciated your words of having a good attitude about work ethics and how we view other people we come in contact with on a day to day basis. I don’t know what your religious beliefs are but your views on what our purpose here on earth is for and how we spend our time each day is certainly in line with what Christianity teaches. Continue to think of others and thanks for all the insights and help you have been and given to me.

Henry Wilson, Indiana, USA




Dear Jestine,


              Did you know where I can buy the the CFL Tester in LCD. Can it test all sizes of CFL Where and How M


De4ogracias Haw


Hi Deo,

I only know about the tester from http://www.lcdparts.net and this tester is meant for testing laptop ccfl and inverter board. Wait, there is another one by HRdiemen at http://www.hrdiemen.es/products/eng/detall_noticies.php?id=3

As for the spec (whether can test all kinds of lamp) i guess you have to email the owner.







ok if the brand is, for example sony so i have to buy a sony flyback also

so now i know, do you have any reference to recommend me a book or a website

all about tv repair…


HI Edwin,
Yes you have to buy back original flyback according to the part number. Books for repairing TV is Troubleshooting Solid State TVs by Homer L Davidson and visit this website too





Hi Bob,


Thank you for providing other ETs that I know and work with, over the internet, to be able to read and gain knowledge and skills from all of your various instruction manuals and newsletters.  I forwarded your website to the four ET websites I use most so perhaps you will gain more membership from those members too.

Thanks for spreading my info to other members!


I have been thinking about purchasing a new hand held oscilloscope that permits me to easily use to view waveforms, voltage levels, and frequency, during my work in customer’s homes.  My Sencore Model SC3100 oscilloscope is great for shop work but weighs about 40 pounds and also requires I carry a heavy isolation transformer with me to plug the TV into while I am making needed tests.

I heard that Sencore 3100 is a great piece of equipment and the weight had really put you off!

So, I am wondering if you know of a good field tested hand help oscilloscope that I can purchase for a reasonable price?  The ones I see in most catalogues cost over $2,000 and don’t want to spend that much money especially with the economy being so tough now and customer’s being afraid to spend their money for needed repairs.  Therefore, whatever new instruments I purchase, at this point in time, have to work well and be economical at the same time.

I personally have no experience in using handheld scope thus i could not give any suggestion about it. However i found few websites which may interest you:




Last, before I forget again, I need to have a scope probe for this oscilloscope that will permit me to view the pulse on collector of HOT to see if horizontal sweep circuit is working properly or not?

Yes you can get a scope probe that have the X100 range.


Thank you for your technical & insightful input on this request for information.


As always, I respect and appreciate your thoughtful responses to my request for information!! :-)

No problem and you are welcome!





Hi Jestine.

This is my first time to receive LCD TV to be repaired. I opened it, and find that it is having 8 X high voltage transformer [4012L 064316 SD-3] on the inverter board. It is using OZ964GN inverter IC. LCD screen does not come on at all. Standby light comes on [red] and also goes out of standby mode [green]. From PSU to Inverter board there is 4 X VCC red wire and 4 X black GND wire. Voltage on each wire is 24.5 VDC. There is also 3 wires coming from Main board.  On each wire where this wires are connected is marked E-PWM,1-PWM and ON/OFF on the inverter board. Voltage on E-PWM wire is 14V but on the board they show 24V. Between cold GND and ON/OFF wire i am measuring nothing. There is no ON/OFF signal because there is no voltage at all. I think MCU board is at fault. If there is any step that i didn’t follow please help.

Many thanks.


Hi Azwindini,

From your description it is most likely the Mainboard problem. The on off signal should have some voltage there. I guess you may need to send the tv to the distributor as it is not easy to get a Main board.





HI Kenneth,

It has been quite a long time now. So how are you and your family?

Me and my family are fine thank you.

I hope by the grace of God all is well. I want to thank you very much for the repair newsletters and all the advices you give to me on how to become a proffesional electronic repair.

You are welcome!

               Please sir, I have a problem with a CRT monitor. It works very well but the monitor looks greenish and dark on the right side. What may be the problem or which components may be bad.

Check all caps in the CRT board especially the Green circuit. Sometimes a bad tube may cause this kind of problem.

I have another problem with another CRT monitor. This monitor comes on with the yellow light on the front panel and produces a tik tik sound on the power supply side of the board. That is, on the side that the power cable attaches on to the monitor. I have checked all the electrolytic capacitors around this area and all reads good what may be the problem.

It may be a flyback problem. please visit this link:






Good day.

A monitor is faulty whereby 1/3rd of the screen bottom size is shrinked or fold over.I’ve checked vertical field stage but i couldn’t find where the fault is. When i switch ON the monitor, it comes ON and shows something like waves moving from top to bottom at start up. After warming up those waves disappear but at the bottom i can still see thin horizontal lines across the screen. I am not sure which stage is responsible for this type of a fault.



HI Azwindini,

Try check the supply voltage and if all okay then directly change all the non polar cap (value of .1uf, .15 uf or .22uf) nearby the vertical IC and retest the set again. These cap may fail under under load but tested good using digital capacitance meter.





 hi Mr. jestine yong,
I have GE TV 12″, the problem is:
Main fuse 220V/2.5A is blown out each time when I change with new one, I think there is problem in the power supply, could you -please advise and thank you in advance.
best regard


HI Joy,

Then you need to check all the semiconductor especially bridge rectifier, power ic, power fet and also check on secondary diodes.





My previous repair with LG CRT Studioworks 520Si which needed replacing the flyback, still sometimes has tick sound when being used, though this is very rarely happens. Do you know what is causing the tick sound again? I had used the genuine flyback and at the time of replacing, I do check the internal capacitor to be OK, about 2.x nF.

From the internal capacitor. It is breaking down under load.

Why the internal capacitor and the voltage divider circuit of the flyback need to be epoxy packaged as a unit? Why they don’t just put them outside, so we could replace the capacitor easily?

Well may be to save cost. During my early days in Monitor repair the flyback divider was located outside and not integrated with the flyback.

What is generally the problem of the internal cap of the flyback? Is it shorted or open? From my experience, the internal cap capacitance is usually dropped below 1.5nF; but my repair with Philips CRT 105 S found that the internal cap became OL ( open ) when being checked with digital meter.

I suggest that you visit this link again:


When repairing LG monitors I often see a component like the one in the attachment ( see FB906.doc ). As you could see in the picture, the mainboard use the item name of FB906 printed onboard. What is that orange-color component, and what is its usage in the primary section of the power supply?

It is a ferrite bead (a small coil) to eliminate interference. Since this value is so small, replacing it with a small wire makes no different.

Also, there are 2 resistors in the picture, labelled as R924& R925 which had been removed because they are all shorted. The value of them both are 0.39Ohm, could I replace them with 0.33Ohm since I cannot find 0.39Ohm at the local store.

Yes you can but not on bigger value like 0.47 ohm.





Now I am repairing LG 505G monitor which is totally dead caused by power surge or overvoltage as described by the owner.

I found some parts bad: Power FET shorted, low ohm resistor shorted, bridge diode shorted, filter capacitor blown, and directly replaced the Power IC.

Now when I turn it on, nothing happens, the monitor is still dead, even the power led cannot light, but I did measure the filter capacitor had 290V DC after the monitor is switched off.

What do you think is causing this problem? Is this kind of problem repairable? Could it be the CPU itself had already blown?
Later tonight I want to check if the crystal has the sinus wave or not, the secondary voltages are there or not, etc.

First you need to check if the there is any output voltages or not. No voltage means the CPU would not work. Have you check all of the primary side components? What about the primary coil of switch mode transformer? Have you check secondary side diodes as if one of them shorted it could cause no power symptom? Does this Monitor have optoisolator IC? Check the optoisolator and nearby components too.






I hope asking these questions is not out of line. I don’t know who else to
ask that has the experience you have.

I was wondering about testing SMD devices. I have some circuit boards that
are loaded with these things and wanted to know if you could maybe cover it
in a newsletter or something similar.

What can you use to test the SMD resistors, caps, diodes, transistors
in-circuit. It doesn’t seem practical to try and remove them to test them
because you will more then likely damage them. Can you go over how to test
them and what you use to test them with so that you get an accurate idea to
their condition. I have a pair of those smart tweezers. Can they be used
or is there something else. I am really curious on what you do when you are
not sure you have a problem and what SMD devices can you check in-circuit.

Thanks again


Hi Russ,

I guess this tester would be a great help to you:






HI Bob,


1). A TV, power is ok but no display. Measured the voltage to the collector of HOT and it gave 130V. Suspected the fly back transformer and changed it with       exactly the same part # but still no display. Tested the components in the fly back area they seem to be okay. I do not know what is exactly wrong. Please advice & how I can troubleshoot.

Voltage to flyback is not good enough to energize the flyback, you need a Base signal to HOT.


2). A TV, power ok, no display. Measured voltage to the collector of HOT gave zero reading. Please advice how I can troubleshoot.

Trace from the collector pin back to the power supply. It may have a fusible resistor open circuit.


3). A TV, power ok, no display. Measured voltages to the pins of  fly back transformer, some gave reading while others gave no reading. What does this mean?

Refer to answer 1.


4). TV, no power. Measured voltages of the main power capacitor & collector (drain) of Power Transistor gave required readings. Suspected HOT so removed the collector pin out of the board but still no power. Other components checked and they all seem to be okay. Please advice.

Try isolate the problem using this link:



Also which pin of the fly back is exactly the B+?

You have to trace from the power supply. Usually the 110 volt dc is the B+ voltage.


If you can send me some additional troubleshooting notes on the “power ok, no display problem


I suggest that you read up this article:






Hi Jestine,

I am from Singapore and would like to visit you to know more about your training and products.

I remember that in one of your technical document which it mentioned Flyback Transformer can be repaired. I wish to send one of the flyback Transformer to you for repair. It is a small flyback from SONY Black and White 9″ Monitor. Could you help?



HI Albert,

Flyback transformer can be repaired if only the problem is the internal capacitor had shorted. If the primary winding or secondary winding have problem then it can’t be repaired. I guess your 9″ Monitor flyback do not have the internal cap thus i can’t repair it. Most probably it could be problem in the primary winding. By the way yes you are welcome to my humble office in KL.





HI Andri,

jika yoke monitor sudah rusak bisakah di ganti dengan yoke yang lain,
walaupun tipe yoke dan monitor berlainan.

Anda terpaksa menggunakan tube yg sama kalau tidak HOT akan bakar ataupun gambar akan out of shape.

Capacitor film/polyester, bisakah di ganti dengan capacitor keramik.

Kalau boleh ganti dgn capacitor yg sama jenis.

Lcd monitor sharp 15″ tampilannya bergaris tebal, bagian apakah yang
rusak, saya cek power supply nya OK semua.

Boleh jelaskan lebih lanjut tentang apa makna tampilannya bergaris tebal-saya tidak faham maksud kamu?

Apa persamaan mosfet FS12UM.

Maaf tiada data untuk part ini. Dimana ia digunakan?

Dan apa code HOT monitor merk CTX model VL500, sebab HOT nya sudah
hilang, dan saya cuba ganti dengan BUH517, sewaktu monitor di on kan
B+ voltage 120v tapi langsung turun menjadi 50v. Apakah itu di
sebabkan BUH517 yang tidak cocok.

Try C5411 dan sekiranya voltage b+ masih turun ia kemungkinan fkback sudah rosak.

Mohon maaf jika saya terlalu banyak bertanya

No problem.






Dear Sir,


Good day to you,



Thank you very much for your report.  It was great.     Kindly help, I have a problem with one of my HP 1740 LCD Monitor..


A message appears (Check Video Cable) when the monitor power up and goes off leaving only the power led (Green on)


I checkd the power board all capacitors are normal not even a buldge is visible there are some dark areas near the inverter side, no break or damage  up of any components.  Photo of the Power Board is attached for your reference.


Kindly advise

Awaiting your kind reply ASAP.



Thans and best regards,




HI Derick,

Check the dark area components for dry joints especially the high voltage transformer. Check the tuning capacitor (nearby the high voltage transformer) capacitance and also check the C5707 transistors for short circuit.





Hi Jestine,


thanks a lot for the repair tips.


And for this one?


Tv- power supply problem.


When on the power the power comes on for seconds and goes off. Checked components in the power supply area all seem ok. Suspected HOT so removed the collector pin and power came on so replaced with exactly the same one, but still the same problem. Checked and found the primary winding of the (small) transformer (probably the driver for the HOT) that is connected to the base of the HOT was open. So replaced with a similar one but still the same problem.

please advice what I can do & what is really wrong




HI Boby,
I suggest that you check all of the components in the flyback area and possible try replace the flyback and retest the set again. The flyback may have a shorted winding.






I have a Benq monitor (fp222w) which works for a few seconds and then shuts down. I opened the monitor and found one (light brown) small burnt ceramic capacitor. I tried finding a replacement but the stores I visited could not find one because they were  unable to interpret the readings on the capacitor.
The readings are: U2 15J 3KV, written underneath one another.

Would you know where I could acquire this part?



Hi Olli,

The part number means it has the value of 15 picofarad with 3000 volt (working voltage).  It is hard to find such a cap even in my local market. Try check form the list of electronic suppliers by visiting this link:


Hope this helps!




Hi mr.Yong

i thank you for your mail. most probably i should by that book next month now i have money problem. do not miss understand me i like your book very much. please answer me  i am repairing monitors. LG 500G when i ON monitor there is called smps tranformar makes tiktiktik sound then i go through internet to find this foult (at that time i saw your book) another site i got some idea about that then i check that transformar that was ok then i check ut put rectifier diodes that also ok then i change main filter capacitor that one also ok then i change all the capacitors near smps but still that make same tiktiktik sound after that i remove the horizontal out put transistor and set a 100watt bulb between collector and emmitor but still makes that sound please give me a good solution for this…

thank you Mr.Yong


Hi Chrishan,

Try isolate your problem using this method:


If the bulb stay light then the problem could be in the flyback transformer area.




HI Bailing,

I had replaced the power IC for the second time, had checked there are 310 V DC at the drain of Power FET, but there is no VCC at pin 7 of power IC. I don’t know why and still looking for it. Also there are no secondary voltages at all. What should I check next?

Try remove the power IC and check for supply voltage. No supply voltage means no secondary output voltage.

According to Acrisoft monitor repair book, there must be start-up voltage ( 12 V ) on the main power supply of the power IC. If there is no start-up voltage, the start-up resistor has blown. But I don’t know where is the start-up resistor.

Trace back from the power supply vcc pin and you will notice one. Usually is in the high ohm range.

How could we know the difference between the China FBT & original FBT?

By the outlook. Generally the workmanship of original flyback is much better than the China made flyback.

Because I fear being cheated by the local stores.

Compare to other branded Monitor flyback and you will have some ideas about it.

I’ll keep you update of this monitor problem. Thank you

Alright thanks!





hi sir,

can you give me some advice regarding to the television that i repaired, i check the HOT, its shorted, i replace the HOT without plugging in the Deflection, its ok, but when i plug it, the flyback transformer came out an arc and hit the red wire of the deflection coil, so the HOT then short again, so i got the idea to put some epoxy on the flayback so that no arc will split over there and i replace the shorted HOT again, and plug the deflection coil, but when i turn on the tv, the flyback release an arc and hit the core of the flyback then the HOT Short again, is this the flyback itself was deffective?is this the time to replace the flyback? or there is some remedy to this kind of problem…

i hope you can help me sir….

more power and god bless….

thank you….


Hi John,

It is confirm that the flyback need to be replaced.





Hi Jestine,

I have a question. I really do not do electronic repair as a profession but I am an electronic hobbyist. Recently my Akai PDP-4295ED (Plasma) TV showed this symptoms: the color is scattered and images are not well defined, like a watercolor painting. As you know TV repair here in the US is so expensive, almost like buying a new TV so I thought if I could repair it myself I could save some money. If you can walk me through it, I am willing to pay you instead. What do you think?



From your description it seems that the mainboard or the panel have problem. Before that you have to make sure that all of the output voltages from the SMPS are good. By the way if you have no experience in performing voltage testing i suggest that you send to a professional to diagnose the fault. If you have other question please do email me again.







Hi Jestine,

Saya sedang membaiki, Lcd monitor AL1917W,masalahnya no power, fuse blow, bridge retifier ok, fet ok, bila saya tukar fuse, fuse blow.Di bahagian power supply ade IC P1337/NCP1337P, Saya rasa ia rosak, apa equavalent utk ic ini, Terima kasih


Hi Ahmad,

Ya kemungkinan besar IC itu ada masalah tetapi saya tidak dapat cari IC tersebut.




HI Andri,

lcd sharp model LL-T15G3-B, kerosakannya seperti gambar yang saya lampirkan

Sekiranya power supply output ok in bermakna LCD panel sudah ada maasalah.

mosfet FS12UM di gunakan di jalur B+, bisa jugakah di ganti dengan IRF630

selain dari IRF630, IRF640 dan IRF634A pun boleh digunakan sebagai pengganti.





dear jestine


i search for  two smd ics that we can’t find it in our  electronic supplier so i ask if you can find it in your electronic supplier (this two ics are smd and QFP package and are fieldbus interface ic)
1-SIM 1-011



2- Frontier-1+



best regards



HI Hamid,

Sorry i could not find that number too. Normally for SMD components the manufacturer will customized the code and only distributor knows the spec and equivalent part number.





dear jestine is the esr better then an ossiloscope to check elecrtolitic cap on board? or i can check caps with no problem with an ossiloscope? as im in doubt of what i should buy first thanks from ray


Both meter have their own strenght, one is design to check on capacitor while the other is to check on signal and voltages. I suggest that you get the Blue ESR meter first as we use the meter more frequent than Oscilloscope.






Hello Jestine,

I don’t know if I’m allowed to wright to you, but here I am. I just want to say many thanks for the great pictures you send to me. I enjoyed it a lot. This is the only way I will ever be able to see how your world were you live, looks like.

I am not a electronic expert but do elect. for a hobby and enjoy it a lot. The repairs I do, is mostly radio and tape players and I do it for my friends.There is one thing I want to ask you, If I may and that is, I bought myself a capacitance,inductance meter. The name on the front is a “UNI-T model no.UT603″.How good is this meter and the other thing, when I set the dial to 2mH I then get a reading of
0.015. What I want to know, is this reading mean 15uH?

Many thanks for all the news letters, help and beautiful pictures.

Have a very nice day,
(South Africa)


HI Ernst,

Thanks for the email and yes it is 15 microhenry.





Why is the Flyback anode cap always so greasy ( also the circle part of pc tube beneath the cap ), what is the purpose of adding the grease?

You got a very good question. With grease it will prevent any air from coming out from the anode more effectively. This is a very sensitive part and if there is some air leak into it it will cause arcing. The circle part separate between the inner and the outer aquadaq layer.

I’m currently repairing high ouput power ATX and don’t know how to read a 2W five-band current sense resistor. When I check it with digital meter it measures 0.3 ohm, but it looks like not tallying with the band-colors? Do you know what is the exact value of this resistor? See the attached photo, please.

Try ignore the last band (black) and test it with BLUE ESR Meter. This is a low ohm resistor.

Another interesting point, at the primary section I found a TOP222Y component. After searching from the net, it is a 3-terminal off-line PWM Switch. I tried to check it with the DCA Analyzer but the result telling me it is a diode network? Do you know how to test this component, because I suspect this component was bad.

This is a power IC and you can’t test it with meter. As usual if you find no components shorted in the primary and secondary section then try replace this IC and retest it again. Here is the link to the ic:








May I know why I am unable to open your website in Mozilla browser? Some times it opens with difficulty and the site has become slow now

Thanks for your email but my side here is okay and i did not get any email from other ERG members saying that the website is slow.May be could you try on explorer?


When we check LOPTs with Blue Ring Tester we have to check only primary winding or other windings in the primary side and seconday windings too? As you know in conventional/linear transformers it is the primary winding that goes bad.

We only check for primary winding because primary winding have more turns than secondary winding. Besides the blue ring tester can’t test on less winding like the secondary winding.


A laptop p supply/charger: When I connect a 24V lamp to the out put the lamp starts blinking. Out put filter cap is OK and other compnents too found OK. This happened after I had dipped the SMPS transformer into warnish and fixed it back. Before that the P supply was OK.

Try check the low ohm resistor in the primary side especially the resistor value with 0.33 ohm, 0.22 ohm and etc. Check also the filter cap in the primary section along the supply line to the power IC.






I recently purchased the LCD monitor repair book and am trying to learn more about flatscreen monitor repair. Thank you for writing excellent reference and sharing your experiences with others.

I would be very interested to know your comments on the probable failure created by radiation from nearby lightening. Electrical storms are very frequent in the midwestern states in the US. Surge voltages travel into electronic gear through unprotected 110V wiring in residences. Many LCD monitors are damaged and might be repairable.

Thanks in advance for your comment{S}.



HI John,

Thanks for the purchase of my ebook. Probable failure would be no power if there’s a surge. Common components that gone bad would be fuse, bridge rectifier, thermister and sometimes the power IC.





Dear mr. yong.

Hope every thing o.k .

LCD monitor ACER AL1917.

The problem is power led off power supply o.k 5v 14v o.k in main board 2 regulator 3.3v one of them gives only 3v I connect 3.3v by ext psu the current shows reading was 500 ma but stil no led on no screen (took off regulator 3.3v).

Do you think is the mcu or memory problem?
psu was a little bit ticking.

Thanks willyam  

Hi Willyam,

Yes i came across such problem before and it was the MCU fault.




How could we know the specs. of a switching power transformer in a monitor circuit?

We can’t know because there is no reference on it. Most of the smps transformer are unique.

Does the label on its back has any meaning?

The label is like the part number and only manufacturers has the information.

I am asking this just in case the transformer is shorted and I need to find the replacement. For example the LG Studioworks 505G has its switching power transformer labeled as 79A355-503 A040325.

Then when you buy the transformer from LG you can refer to this code but smps transformer rarely have problem.

Today a customer handed in a Dell LCD 15″ monitor with the problem of display has many disorder vertical & horizontal line as in the attached picture. Is it surely the LCD panel problem, could it be repaired?

Yes it is LCD Panle fault and it can’t be repaired.

Every time I repair computer ATX power supply which has varistor in its primary section, the varistor is always being wrapped by shrink-tube. What is the purpose of wrapping it? See the attached picture ( between the big filter capacitors ).

Usually when there is a surge, the Varistor or the fuse will blow first. When it blow the outer layer will probably fly into pieces and the shrink tube will eliminate this problem. It depends on design as some other power supply do not have any shrink tube to cover it.




Your Name: Harindra
Message: HI,

I am on your site for quite few days since I am repairing a monitor that I own.Its old. manufactured in 2000.

Synmaster 750S is the monitor. And I have the schematics. HIgh voltage is OK, but there is no raster. G2 OK, heater working. I found two shorted transisters in the EW section of deflection part. Transistors are KSD2058 and STS5343.

I just want to know what happens if EW is out( i just dont know. I am not a professional repairer.). And why it is there and what it does.


Hi Harinda,
If the EW component is out it will cause pincushion problem. Which mean both side of the display will squeeze inward. try change the transistor and retest it again.





HI Jorge,


I wrote you a while ago about the “Testing Electronics” ebook I bought from you. You also recommended the book by Homer L Davidson. Well I bought 2 books from him.


I am studying solid state TV repair. I have gotten a lot of theory also from acticles like your power supply repair and Samuel Goldwasser. But I still cannot repair a TV because I have no practical experience. Do you have an ebook for sale that teaches solid state tv (CRT) or how to put the testmeter probes to check voltages.

Yes i have the LCD Monitor repair ebook that teaches you on how to use scope to see the right signal and also to perform voltage testing.


I live in Belize Central America and CRT tv will be here for the next 10 years. But no one teaches TV here in the whole country.Some people are starting to get LCD TV. So I will try to learn that as soon as  finish learning CRT.

You got a market there as my country here the CRT is slowing down and more people turns to LCD Tv or LCD Monitor.


Do I have to learn CRT TV repair before LCD TV Repair? Or can I go directly to learn LCD TV Repair.

I suggest that you get the LCD Monitor repair ebook first as it have related to LCD TV repair. You will also have a better idea on how to repair CRT Monitor. Do not worry as i will be on your side to help you out just in case if you have any question.


I learn from your site about a friend who bought from a fake company and lost about $2000.00. So where can I but good equipment safely. Is this company legitimate? http://www.electronix.com/catalog/default.php/cPath/17

Yes, the company already been in the business for many years.



Thanks for all your articles. I read them all

You are welcome!






HI Khosa,


You know I’m having a problem with my television.

It happened one day when I switched it ON, it shows me a blue screen indicating a locker on the right hand corner of it. Now I can’t be able to access anything from it, even if I try to press any buttons it doesn’t change the state. The only thing it can do is to switch On/Off. The name of this TV is Sinotech.

So I want to know from you what might be the cause of this problem.


It might be some factory service code or the data in the eeprom have error. The only solution is to send it back to the distributor to repair it.





hi sir jestine, my friend ask me how to repair sanwa 360TRF multitester. Unfortunately the selector switch was place to resistance when he was testing 110VAC, so in short, the resistance meter was damaged.when i removed the cover the fuse is ok but the foil pattern was damaged. i have also my sanwa  360TRF, so we compare the ckt so that we can trace the connection of it. but when i returned the cover, the resistance meter of my sanwa is no longer operating, i didn’t touch anything on any parts of it, how come that the resistance meter in not moving anymore?, why it happen sir? do you have a schematic diagram for sanwa 360TRF sir? i wish you could help me sir, thank you in advance sir


HI Jonathan,

Sorry i do not have the schematic diagram. Normally here we do not repair multimeter because it is so cheap and if the meter have problem we just buy another one. However it is good to check so that one can learn about the meter circuit. I guess you have to try put it back again and check if there is any lost connection.





Hai Jes !,I Shah from Parit Buntar Perak,I have a Tv brand Sony 29″ to trouble shoot. Problem is picture tube red colour,after I check this problem 1 colour gun KO,So I need your help / Idea to soft this problem.Do you have any method to repair picture tube or others company at malaysia to repair picture tube ?.

My blogspot : http://kejuruteraanelektroniksh.blogspot.com


HI Mohd,

Nice to know you and good to know that you have a blog. Since you have confirmed that the gun was having problem, the solution is to replace with another tube or you can try this method from the link below:






HI Said,

1)how can i test these eeprom ics? 2)how can i know which ic is defective?

 By comparison with a good similar IC and to use a eeprom programmer. If the eeprom can be copied then it is good but not the data.




HI Tan,

 I need an inductor tester.

Sorry i do not sell inductance meter.

Do you recommend the Blue coil tester?

Yes if you want to test the condition of smps primary winding, B+ coil, crt yoke coil and flyback transformer primary winding.

If on a PCB board, an inductor is found to be faulty.. I still need to replace it.

It the inductor burnt?

Does this mean I still need to get a Inductance meter such as hand held LCR meter to confirm the Inductance (Henry) readings? or getting replacement item.

If you have the spare part then you don’t need to test the value. However if you rewind the coil on your own then you need to check the inductance reading.

The are are inductor that do not have any marking except 3 dots, how do we really know the inductance?

Test it with inductance meter


What is your best price for Blue coil tester?

Kitset is RM230.00 and fully assembled kitset is RM330.00 (inclusive of transportation)

Is the light indicator good enough to determine faulty inductor, or perhaps just using normal continuity tester is good enough to confirm the fault?

Yes it is good enough as testing coil/inductor is a bit direct. Continuity checking is only for resistance test which is no accurate because a shorted coil can have the same resistant resading.


What is frequency of the Blue ESR meter is operating?






dear jestine thanks for your helpful high voltage news it s very useful and
explained well, but i must ask you 1 thing how can i figure out which is the
safety capaciter without a diagram?? Thanks


HI Ray,
Look for the cap that have the highest working voltage like 1600 volt or 2000v (2kv) that is located nearby the flyback area.





Hi Jestine yong,

Would you please let me know how we can remove pressure spot from LCD or


Hi Abdul,

Some suggest to try on using hair dryer but i haven’t try it out yet.





Your Name: Waleed

Message: greetings to you my friend. I just want to thank you for your recent artical about the monitor and tv shut down. it is great. I have a question though, how do you measure the capacitance in a fly back transformer. I know it can be done from the anode to one of the legs on the fly back transformer but my question is what let? Thanks


Hi Waleed,

You are welcome. Measure the capacitor between the anode and the capacitor pin which is located outside the transformer. If you see the “C” curve of 10 pins underneath then check on the right hand side top pin. That’s the capacitor pin. More info please visit this link:





Hai Jes !

          How a u Jes ? I need u r help Jes,I have a problem to trouble shooting TV samsung model : CS-21V10ML.Problem is Horizontal transistor burn after 2-5 sec,power supply to collector horizontal is normal ( + 125 V ).I think current have a some think wrong.what do you think about this problem.


From : Shah


Hi Shah,
Try read this post at http://www.jestineyong.com/?p=403






hi, having a look at a A-Open lcd monitor. power led flashes, told it could be the inverter. what advice and where can i locate this inverter. Thanks.


HI Vis,

Is the output voltage from the smps stable. If it is stable then it could be the fault of a bad mainboard. If the output is not stable (fluctuating) then check on the smps area and other shorted components in the inverter side that had cause the power to blink.




hi justine,


How are you Justine?I just to ask you something about the trouble of a samsung monitor the model  is 753S.The OSD always appear on the screen.I change the eeprom and the microprocessor but still same effect.Did you have suggestion you advice me to solve this problem.Thank you  for your time Justine.


Hi Jon,

Try check the supply voltage to eeprom ic and make sure the crystal frequency is correct.




hi  jestine how  are you


this  is  a crt  monitor (LG GRAY COLOR NON FLATRON
) problem that puzzle me …..distiortion  in the left side of the screen  that is  expanding to the  up the center  i contacted  randy fromm from usa  he suggest to replace the caps that is  b+  line  and  if the smps is  synchronized to the flyback frequency  he  suggest  to replace the caps of the smps i replace  them and …(may all of them  but those  caps  that is on  low  voltagelines  like 12v 15 v  5v }  nothing  happen the  symptom  stay as it is  i tested  all  simcondcutors  in the horizontal area ..i ring the  line  transformer  in ciscuit it rings  only  3  …when i  disconnected the  yoke  it  rings  full  bar …i tetsed  the  cermaic  caps  that is  used for  tuning in the horizontal  circuit i tested them  for  obvious  shorted ..nothing is shorted …so could it be the yoke ………….when i ring the yoke alone  it gives  me  4  which  not  good  yet not bad …


Hi Wael,

If it is a 14 or 15″ CRT Monitor and you got only four LED bard from the flyback tester, this means the coil may have partial short circuit.





Hi Bailing,

Thank you for the July’s newsletter about shutdown circuit in CRT Monitor.

No problem!

I’ve just read the Q&A 34 and a bit surprised to know that you’re saying repairing LCD monitor is easier then CRT one?

Yes because LCD Monitor consist of lesser circuit and it is small in size too.

My problem is how could we make the voltage test when all the cables are so short, leaving no space available even just to peep inside?

You may solder a wire to the test point and check the wire.

And how to make sure whether the many pins IC ( scaler, timing controller, etc ) has already got the supply voltage, since our normal meter probes are just too thick?

You may solder a tiny pin yet sharp to the side of your test probe

I often see the service manual tell us to measure whether there is supply voltage at pin 1XX and 4X at one of the big ICs, for example. How do you manage to take the voltage measurements in the newer type of monitor, since they get smaller parts than those described in your e-book?

I only test on the important points and not all points and solder a tiny wire for easy checking

Is it safe to power the LCD monitor on without connecting the high voltage cables from the inverter to LCD panel, since these cables are really made too short?

Yes you can but it will shutdown.

and how about disconnecting the LVDS signal cable when powering it on?

Yes you can and in some cases you will get only white display.

How is the rate of success to overcome the bad mainboard problem? Because every time I study from your Q&A, the two big problems are mainboard and LCD panel, leaving us have no choice but to return it to the owner.

It happens also to LCD TV. The chances to repair the mainboard is actually quite slim because all function have been saved into the MCU and once the MCU have problem it would be difficult to repair the fault unless yo have the same data and the programmer.

When I open the case of a Dell E157FPc LCD monitor, I could ony see one big IC ( Genesis gm2621-LF ). Recalling your e-book about LCD Monitor Block Diagram which at least has 3 big ICs, where are the other big ICs located? Is it now more ICs are placed inside the LCD panel?

Nowadays many IC’s already integrated into a single chip thus making the mainboard even smaller.

Best Regards,
Jestine Yong




hi  jestine  it is  17 inch monitor and  have  expanding  distortion  at the left  side  and  the  yoke  rings  4  and  when  removed  only the  flyback  rings  full  bar


HI Wael,
Its is quite hard to say because the led result is in the marginal area. Some 17″ tube have 4 bar while to some have 5 or 6 bars. I suggest that you compare with another 17″ crt tube. I came across a Monitor that the width expanded horizontally and it was cause by a bad eeprom data.





I have LG cd prayer when insert into power it trip generator off,it has no sound. how can i work it and its cause.



Check the power section for any shorted components particulary the power FET and some other non polar that might have been directly shorted to ground from the live or the neutral line.






I plan to buy ESR meter or capacitor checker


I need your opinion about Good ESR meter.


May questions is:

     1. What kind of tester that can check SMD capacitor (Electrolytic / Not electrolytic)

             or all kind of capacitor.

     2. Tester that easily repairs because of accident test of high voltage charged


      3. The reading value that easily understood and identify the bad and good



Sencore meter which is very expensive-http://www.sencore.com/products/general-test-measurement-equipment/75



A lot of ESR meter available in Internet including your Blue ESR Meter confusing me which one is superior.

            *Blue ESR Meter

            *Cap Analyzer 88A II

            *Capacitor Wizard


            *Product from china and more that found in Ebay


Even I found the ESR comparison web site; still I don’t understand which one is good.



I hope you will help me regarding this matters.


If you are on budget get Blue ESR meter as i found it to be very good. Try read my article on this meter at:



If you have other question please do email me again.





HI Bailing,

I’m glad to know you have another new student from Zimbabwe.

Hope he will be coming in this few months time so that i can train him personally

This monitor have already been sent in for almost 1 month, and it seems the problem is only FBT internal capacitor open. Every time whenever I need to buy an FBT I have to go to Surabaya, but this time there is no FBT type LCE CF 1871 available in Surabaya, even in several websites like Donberg and BIC. It seems this FBT type is rarely used.

Do you ever sustitute this FBT with another FBT, what is the common substitution type?

It is difficult to find substitution because most of the flyback pins are unique. Have you try http://www.hrdiemen.com ?

Another point that I want to share with you is whenever I repaired the high power output ATX power supply last time, I did check the primary of the SMPS transformer with the blue ring tester and the result was all LEDs were lit, but the only culprit I found was a secondary diode UF202G shorted. So my conclusion is the result that all LEDs are lit with blue ring tester doesn’t guarantee that all the secondary diodes are good. What do you think?

Could you try to use a plier to fabricate a short between the anode and the cathode pin of the secondary diode and check to see if the led decrease or not? Generally it will affect the ring tester reading. I wish to see how this diode was connected so that i can get a better picture but i presume that you have sent the power supply back to your customer.





Hi Shahzad,


I am also Diploma in electrical and Iam working on PIC Microcontroller last ten years.

I have made many projects on PIC microcontroller detail is given below.


1.    Digital Control System for Petrol Pump Filling Machine

2.   Digital Alram System

3.    Oil Filling System

 4.      Digital Testing System Motor Cycle System


  After completion of my diploma I working on Electrical control panels. I can only makes good logic for control system.


I am also involved for repair of PLC base & CNC lath & milling machines.


I love working with new micro controller projects development.


I am gaining a lot of knowledge from your website regarding testing electronic components and electronic repair. I need more knowledge for development of microcontroller base projects. Kindle help me in this regards,

Thanks and have a good and a wonderful day my friend!

Thanks for your email-but sorry i guess i can’t help you on that because i’m more on the electronic repair field and did not involve in programming  and designing of micro controller circuit.





HI Noel,

Thank you for your monthly repair news,aside that, to your advice to all the technician and reader of your site, about how to become a prof. technician.

You are welcome!

I am not only reading your post about technical issue,I am always waiting for the issue regarding how to run/manage a business in electronics servicing.

I will consider that topic.

By the way, I am now running my own business,I talked to my Boss that  I am resigning to the company and put up a service center to our product.And my Boss agree with me to that with out any question,he told me, if I want a help or assistant to my business he is willing to help me,and now I am the only one authorized service of their company.

Nice to hear that you have set up your own company

And this is because of your post that I read,“NEVER TRY, NEVER KNOW”.Before I’m always worried on how to talked to my Boss that I am resigning,but because of this word
I have a guts to do it.

Yes sometimes in our life we cannot always be in the safe side. We got to take some risk in order to see a better result.

Thank you Jestine for all those WORDS that’s inspired me and “MAKING MY SELF BETTER THAN YESTERDAY”.

Thanks & Regards,

Wow!- Congrat! You have put your idea/plan into action and now is to execute the plan. When you plan a seed then expect it to grow and bear fruits!

Best regards,
Jestine Yong




gud evening.


Hello again. I had an experienced with shutdown problems specially with crt monitors for computers. I wonder if the collector voltage of the tv monitors are higher than that of the computers.  I mean the applied collector voltage on the HOT for tv’s are higher than that of the computer crt’s? Finding a diagram for computer crt is quiet difficult. Anyway, thank you for this newsletter and I appreciate it very much.


Best regards,



Hi Bong,

For tv collector voltage-yes generally it is higher. Try find schematic from http://www.eserviceinfo.com





HI Damdin,

It was very big luck for me to know about you. I think you are very talented man in repair service.

Thanks and you are welcome.

I’m just starting my repair service. I very like to spend all the day making repair, but I’m not so good. I’m almost beginner in this but managed to repair some TVs and CRT monitors.

My sister in Poland bought your “Testing electronic components” ebook for me.

Right now I have a LCD monitor AKIRA model LCT-22VA2ST. It has following problem: When turn it on the screen shows normally for 2-20 seconds. After that the sound remains but screen go off.

Please could you give me your advice how to locate and fix the problem?

Try check the backlight as if one of the backlight fail it will cause display to shutdown. And make sure that there is supply voltage to the inverter ic. If no supply voltage then suspect a bad mainboard.





Hi Jestine,

I have your “Testing Electronic Components” book and also enjoy your monthly newsletter discussing various aspects of electronics (TV) repairs. It is very helpful and I am learning a lot from that.

My background is in general electrical engineering but being encouraged by your writing I am trying now to revive my long time broken VCR.


It is short-circuited in the power supply and I found that the fault is actually in the bridge rectifier.


The component is marked as S1WB S60 97. As yet I wasn’t able to find a suitable data sheet for that or any reference on a compatible supplement.


Wonder if you could possibly help me with that. It would be greatly appreciated.


Best regards



Hi Henry,

Thanks for the support of my ebook and nice to know about your background in electronics. Sorry i could not get the datasheet too. Normally if i can’t get the part i will fabricate my own bridge rectifier by using 4 pieces of 1N4007. If you have other question please do email me again.





Hi Bob,

1). no power : measured the voltage across positive & negative terminals of the main power supply capacitor which gave zero reading. Then started measuring voltages from the main line to the rectifier diodes and all gave required readings. When I measured the voltage after the ouput of the rectifier diodes there was no reading – gave zero. What does this mean and where actually is the fault?

The problem is before the rectifier. Try check the input ac pin of the bridge rectifier.

2). no power: measured voltages across the main power supply capacitor and the drain (collector) of the switching FET of the main power supply and both gave required readings. Does this mean that all components in the power supply are ok, and what other possible areas or componets that I can check.

Have voltage does not mean it is okay- you got to check the output waveform from the power ic.

3). for the photocoupler, pin 1-anode & pin 2 – cathode so tested with a digital meter using diode symbol for both forward & reverse bias and both gave 1. Does this mean that it is bad?

Yes, it should only have one reading and not showing 1.





HI Jerry,

Thanks always Jestine for your very helpful monthly newsletter.

No problem!

A week ago I am repairing Sony XF-25M50, There is no b+ when i float the HOT collector, also the hot transistor has leak in collector to emitter junction. I check some other faulty parts diode, capacitor etc. around the power supply area & also at the horizontal circuit, making sure there is no other shorted or leaking components b4 i put new voltage regulator. When i replace the voltage regulator, I got b+ voltage w/o HOT connected, so when i connect the Horz. out transistor I heard the flyback start but then collapse the high voltage again, i check the HOT transistor alamah matie again Sir Jestine, I told the my customer, the flyback transformer must be replace. when i replaced w/ new flyback transformer, I mistakenly interchange the cable of the flyback transformer, G2 cable i plug to the ground then ground to the G2 terminal. I already switch on the TV, then I notice the heater lit up but no screen voltage, when i inspect oh my God i plug to the wrong terminal. then when I correct it then switch on the tv again, there is bright picture but has retrace line. Do you think I damage the Picture tube sir Jestine just because of this mistake?

Possible but sometimes a mistake could cause other components to go bad that you need to chceck it out. Concentrate on the CRT board area.

pls help me how to explain to the customer. I pity him also because this is his only TV.

Tell him that you are still reapiring it and need more tim

I think i damage the RGB cathode. I check RGB one x one its ok nothing wrong except the picture so bright & has retrace line. when i reduce the screen voltage the picture turns green then retrace line very visible.

Check the green colour circuit.

Thanks Jestine. I appreciate your goodness, good ethics in writing to your lots of customer. God Bless you all the time.

You are welcome!





I got the AIO printer with Fax but fortunately the printer (telephone port0
was faulty due to lighting. Can it be repair ? normally which parts go
wrong? Repair cost ?
Or I can send u the board for testing

Yennie Tan


Hi Yennie,

It depends on how severe the problem is and usually when telephone part hit by lightning the problem would be hard to repair due to too many bad components and those components is not easy to get from the market. Technicians will usually replace the board than to repair it.





Hai jestineyong…
my name is irwan, i’m very grateful to read your testing component ebook…
i want to ask a question to you..

I have PC with spesification:
MotherBoard ASUS P4P800S-X
Processor Intel Pentium IV
2 Harddisk Seagate 80 Gb
PSU Simbadda ATX lansing 400 W

last sunday, my pc couldn’t be turned on. i have checked it, and i found that power supply was broken. After i opened the casing and cheked the component on power supply, i found the break down capacitor 470uF 200v and replaced it with new one. next, i tested it and my pc can turned on for 3 second and then turned off suddenly. I got confused to repair it,
could you help me to solve my problem ?


Hi Irdi,

Try check corresponding components in the capacitor area. Make sure the power supply is connected to board otherwise it will shutdown after turned on.





HI Karlo,

It will take some time familiarizing with this cool gadget.

Yes you need time to play around with it.

1. I calibrated my ESR meter using the 82 Ohms 1% resistor and then the 5.6 Ohms resistor.

I was able to read the 82 Ohms but cannot read the 5.6 Ohms.
I tried to switch it OFF, then turn it ON again, short the probes to get zero then tried the 5.6 Ohms. Now I got 4.2 Ohms. But using a DMM I got 5.5 Ohms. How do I improve the accuracy?

Generally once you have calibrated  82 Ohm you should get a near result of 5.6 ohm like 5.4 ohm and etc. In your case i guess you might need to recheck the components again or try to test on another resistor. Try post your question in this forum:


2. I have a couple of good 2200uF/50V capacitors. In the ESR meter, it is .00. The capacitor is fresh and not yet used. I have five and all have the same reading. I tried higher caps and got the same. The reading is ideal or too good to be true. I am confused with shorted caps (because it was tested good in the analog and capacitance meter) and an ideal capacitor (zero ESR) but in your blog you mentioned .00 is shorted.
A similar reading when we touch the test leads.

Try change the test lead- Are you using the same probe cable or other probes? However this problem could lead to question no 1.

3. What are the XXX marks in the ESR chart?
This is bob parker’s chart and as for me i treat it as “i find my own answer”. That means i will test out the cap esr labelled as XXX and jot down the result for comparison.





Hi Jestine Yong,

We have around 43 computers (assembled and Dell) in our office at Chennai,
. We have been facing peculiar problems for the last one month in our
organization. The PCs would all shut down at the same time at random. All
PCs are connected to UPS. The UPS does not fail. There is no power issue or
network problem. No virus either. It looked like there was a problem in the
SMPS. We changed the SMPS in all the machines. We changed it to brand
Zebronics. But the problem continues to persist. Would you have a solution
to this problem?



HI Geetha,

I do not suspect power supply problem because it can’t be all shutdown at the same time. It is the source of the computer shutdown problem. Try get a technician to check on the AC LINE and make sure the voltage will not fluctuate and if it fluctutate then get a building maintenance engineer to look into the problem.





Hi  Mr Jestine Yong,


Thank you alot for allowing me to correspond with you.In fact,I have a 54 cm tv model no: cz-20j50.When it was brought to my workshop,the tv was totally shutdown.I opened it and found out that the horizontal output transistor is shorted.I replaced a new one but unfortunatly I got a blue vertical line on the screen.I checked the voltage at the anode of the horizontal output transistor,I got 115 volts.I repladed the horizontal oscillator IC but in vain.Still i got that blue vertical line on the screen.I checked for a possibly shorted transistor,regulator,or diode but didn’t get any.

Please,can you tell me what possibly can be wrong with the tv ?


I would also to order the e book LCD REPAIR.Tell me please how to proceed so that i get it


My best regards.


Hi Kandall.

A one vertical line (from top to bottom) suggest that the problem is in the horizontal yoke coil connector are. Check the yoke coil (make sure no open circuit) and the corresponding components. By the way the LCD TV repair website is belong to Mr Kent an you can join his membership HERE.






hi mr young, how are you. i have a problem with a monitor and i dont know how to solve it. the monitor power on normally but the image is not clear ( the windows icons are deformed and stretched  horizontally  ) and there are horizontal bars that moves down to up. i have joined a photo of the monitor. thanks.


Hi Achour,

Try replace the horizontal/vertical oscillator IC and the cpu to test it out. If you have a scope you could check if the horizontal or the vertical ic signal  is good or not especially  when checking on the hsyn and vsync pin in the horizontal/oscillator IC.




Your Name: Jan Pedersen
Message: Hi, as a member of your great site I’ll like to know some tips about a proble I have.

I have an lcd monitor that works about 2 – 5 sec. – then it turns off, I’ve looked at all capasitors and components inside, it lookes fine. Why am I loosing power and where do I have to look for this trouble?

I think the problem is on the inverter board, but where? Or is the problem the power to the inverter board? If so, I like to know what power the inverter board needs to work – (12v?)


Hi Jan,

Check the back light as a bad backlight could cause it to shutdown. Once shutdown make sure the inverter ic still have the supply voltage, if not then suspect a bad Mainboard. If the supply is still there then check on the inverter board to look for dry joints in the high voltage transformer pins, bad semiconductor , bad tuning cap and etc. Hope this helps!





Hi Toby,

Thank you for yet another informative article. I really appreciate each one.
Incidentally, a LG 19″ television model #RP 20CA10 came into the shop with High voltage shutdown problem. When the power is turned on, a bright orange flash appears at the neck of the tube above the yoke, then the t.v shuts off in about two seconds. If I press volume or channel buttons, the tv cycles on and off by itself for every two seconds. I,ve changed the safety capacitor, HOT, STRF6624, and another capacitor in the power supply.
I took the vertical I.C out but the problem still persists.
I unplugged the yoke but the tv still shuts down. Am I overlooking something?

CRT flashes indicated problem in the tube or the flyback generate a too high voltage. What is the B+ voltage?

My second problem is with a Quasar 27″t.v model #SP-2725F, chassis #SC 363. This t.v came to the shop with no vertical deflection. I changed the Vertical IC LA7838. I changed a low value resistor which leads to the flyback. The t.v powers up with three inches of blackness at the top and the bottom of the screeen. I changed all capacitors around the vertical IC but the picture doesnt open up all the way above and below.
With the t.v on for about 15 to 20 minutes, the picture squeezes in to a thin horizontal line again. Am I overlooking something here again?
Have you check the supply voltage as a bad supply voltage could cause such problem. Sometimes a bad vertical yoke coil and loose connection in the convergence board may cause such problem.





Hi Jestine,


It there any different between IC LA7845 and IC LA7845 ended with an alphebet ‘N’ i.e. LA 7845N?


Can it be replaced with each other?


Kindly advise.


Thank you.






Hi Richard,

It depends on the circuit as some could support and some don’t. Fro example a power IC TDA1504 and TDA1504AP is different. I guess you have to try it out and see.





HI Otto,

Thanks for that Jestine. I know I probably shouldn’t do this via email, but since I got your attention, I hope I can pick your brain just a bit more. Before this happened, it booted up fine and worked but I noticed that it was flickering, which it had never done before. It continued to do this for between 5-10 minutes more, then just went black. The power button stayed lit. It did not blink.

Yes a bad backlight could flicker before the display shutdown.


Now, when I turn it on, it stays on for no more than about 5 seconds or so then goes black.

Most probably the backlight already heated up and it flick even more frequent.

I can still see the test pattern on the screen using a bright light. From all the reading I’ve done on the internet, this leads me to suspect that the problem may be my inverter or my backlight.


Trouble is, how do I determine which one is the culprit?

Try replace backlight first.

If it’s the inverter, is it just a matter of replacing the C5707 and FU9024N transistors or isn’t it that simple?

This you have to test it out with your meter to see if the components have problem or not.

I DID check the PF751 fuse and it gave me an ohmeter reading. If I do replace it though, what do I replace it with and from where?


Replace the backlight and test it out first before touching the inverter board.






Hi Yong,


We can check the esr of electrolytic capacitors on board (while the capacitors is still in-circuit) by the esr meter this truly save our troubleshooting time and my question is what about their capacitance (that we can not check on board)?


Does esr reading ok means capacitance ok?

Generally yes. If ESR reading Okay the capacitance value also within range.

If we check the esr reading is ok(capacitor on board) do we still need to check its capacitance?

If yes that means to say we still have to remove capacitors  from board to check the capacitance.

Am I correct?

No need to check on the capacitance because when a cap have problem the ESR value will shot up very high.

Best regards,



Hi Parusdi,

althought i cannot speak and writen english so well as you, i always read email by email from you, Mr. Young.  I realy proud of you make suggestion for people who want to succed for the next life. I am very sure what you give all the good useful thing to all people in the world you sent the email, they will happy and be sure what are you do thing right.


i am intereted in how to fix a dead mainboard computer, how should do firts  Mr. Young?  i have a mainboard trouble can’t on when i press the power on switch. I touch the chipset is too hot, it seems trouble with that.
I try many way even the change processor, ram, or vga but all not give help. The brand is ECS (elite).  I am not work in the offce i am free lance technician of computer. I wish i could buy your book but i have to be patient.

If the chipset is too hot then most probably that is the cause of the problem. I guess you buy a new board which is better because it is quite hard to get those chipset

I am from Indonesia, live at jalan sungai riam Rt.03/02 ps.kliwon blkang sd-al-irsyad Surakarta, Indonesia.

Thanks for the info.

i have YM yasin yasir…

Sorry at the moment i do not have YM.

If you want give the solve please allow me say i have to buy your book even I have to patient.  please don’t be angry with me Mr.Young even i am not plan to buy your even from now. But I am sure I can someday.

No problem -if you have other repair question just email me.



Hi jestine Niten here,i justed needed your help in fixing one of the tv’s.It is
a JVC brand and the model number is:AV- F21T3.The problem with that tv is that
i do get the +B voltage and also the tube does light but i cannot see any
raster signal in front and also the timer light is on full time together with
the stand-by light.i dont have the circuit diagram of that tv and it would be
really gratefull if you could help me out….



HI Niten,

What about the G2 voltage at the CRT board. Without or lower G2 voltage will cause no display symptom.





Thank you Jestine for the report, i hope it will be helpful to me. but i have a question. I have a samsung SyncMaster 912n Lcd 21″ monitor which after working for some time it goes black and shows a message, “not optimum mode”, what should i do?


HI Kizza,

This is a common fault and the problem is in the MCU. You are either replace the Mainboard or reprogram the MCU again. Hope this helps!







Hi Jestine

I have come across a 6 legs FET(see attachment), not sure how to test whether it is shorted or not. Your LCD manual only mentioned about 3 legs FET.

Can you advice?



Hi Spencer,

This is a power IC and can’t be test using multimeter. That means the power IC and the power FET already integrated into one single chip. You can only check the input voltage with meter and test the output waveform with scope.



Your Name: Anthony Pleticos
Message: Not a technical question, I have found the problem with basic ohmmeter (of course tv is not connected to power!) -removing transformer from pcb, found a short in the primary where they should be two separate windings.

However, where if panasonic don’t stock replacement and HR-Diemen don’t stock replacement flyback, where to go? Pinouts of transformers are not all the same!

Please suggest on your website where to get transformers.

Thank you,

Anthony P
Sydney Australia

HI Anthony,

There is no other way. Normally i would suggest them to visit either the distributor or HRdiemen.



Hello  Jestine ,


I  had successfully  downloaded  the report  on smps  it is very informative  to me .  i need   some help from  you. presently  i ‘ m repairing smps  of  lamda  make  model :- alpha 400W  . In the initial  stage  power factor correction circuit is used  with IC L4981AD  .A  boost up regulator  ckt is designed using  2 mosfets. when i give supply 230vac  the mosfets blow  up .what could be the reason. Can you help me please? I will be very thankful to you.
Thanking  you


HI Ninad,

If the fuse blow then check on the semiconductor components and also the primary winding of the smps transformer for shorted turn.



HI Vic,



1) Can a 5 striped resistor be replaced with a 4 stripe resistor as long as the ohm’s and wattage are the same. (Why do we have 5 striped resistors)?

Yes you can. 5 band resistor could provide more accuracy compare to 4 band resistor. For example 5 band resistor could have the value of 22.5k, 22.8k and so on but 4 color band only could have 22k.


2) Can carbon film resistors be replaced with metal filmed resistors as long as the ohm’s and wattage are the same?


Yes it can but i still prefer to use back the original type. You can try one and test it out to see how the result like.



HI Bailing,

I’d like you to help me with this monitor. The problem is after turning on the power switch, there is no display at all, no high voltage, only saw the green light blinking with the tic-tick sound from the relay. The tick sound came at the same time with the blinking of the green led ( no vga input ). Giving an input to the vga connector just make the blinking and the tic sound go faster.

I have downloaded the service manual, but still don’t know whether this kind of problem is because of shutdown, DPMS failure or no power supply problem. What do you think is the cause of the problem? The primary section uses the Fairchild power switch ( 5pins ) instead of a N-Channel Mosfet.

I guess you have to use this link to isolate the problem first:


then let me know the result.

Another question is do you ever use “rapidshare”  to find service manual? Is that helpful? I’m asking this because this service is not free.

No i’m not using that service so no idea about whether it is useful or not. I guess you may need to try it out.

Have a great day!








HI Julianto,

I have a shorted SMPS, the fuse at the primary side is blown. I check all the component at the primary side, all is okay. I try to remove the transformer, replace the blown fuse and I plug it into AC, the fuse is okay.

Then I put the transformer back, but I didn’t connect the secondary side with the transformer, I only connect the primary side of the tranformer. I plug it into AC again, and the fuse blown.

I want to ask. The last thing I do, is connecting the transformer with the primary side, but not the secondary side, does the transformer is working?

Does the fuse blown because of a shorted transformer or because there is no secondary side connected to the transformer?

oh, I allready test the transformer using multimeter and it’s okay, and the transformer is physically looks fine.


You can’t test without connecting the secondary side as this could cause over voltage in the primary side (no load) and blow the fuse.

Hope this helps!



Hi Kumar,

Many thanks for the manuals and your monthly newsletters as with those basic testing of electronics components i have been able to solve many electronic appliances problems. Also i had always believed in basic working principle of electronic components to be able to repair electronics.


You are welcome!

Mr. Jestine, I would like to seek a help from you concerning one TV problems on which am spending a lot of time and money as well and not being able to solve the matter.

Its an Akai CT-P34NABS TV and i don’t have the schematic diagram. Actually the tv is not starting and i could hear a hissing sound on the speakers and found the IC TDA9341PS/N3/A heats up within seconds. I guess that this IC must be faulty but before i purchase it i would like to confirm if its the same causing that problem.

If the IC heat up then most probably the IC have problem but as usual one has to confirm that the corresponding components is good otherwise the new IC may burn again upon power On.



Hi Mario,


Sorry, but I forgot to ask you questions regarding the 15″ EIZO Brand lcd monitor.Symptom: NO POWER! Have you encountered problems wherein its secondary 5V and 12V DC output is fluctuating and or oscillating? I mean, as I measure secondary voltages via analog multimeter- the meter needle does not stay put on the meter reading scale and keeps moving like a car wiper. I already check and replaced its optoisolator (due to minimal leak, X10K range, on pins 1 & 2 – is this normal?).

I guess you may need to check all the primary section components and sometimes a shorted component in secondary side (inverter  board) may cause power to fluctuate.

How about minimal leak-meter needle move a bit from infinity- on FCH20A10 secondary diode?

A schottky diode will have some leakage in reading.

I’m trying to suspect the 1M0365R PWM/FET IC,have you encountered this component and is it possible to test this IC?

You can only test the input supply and the output waveform with scope.



Hi Jestine,


In some countries if a technician is working on electrical equipment that is powered from the wall (Mains voltage 240 v AC) the organisation needs to have a registered electrician to oversee the work.  Particularly on the side of the mains wiring.  In practice the registered electrician does not actually inspect every job but is responsible for the repair or job to have been done following industrial practices. 

A qualified registered electrician is a person who has served practical time with on the job training, passed formal examinations on electrical regulations and accepted industry practices. 

My question is, for a commercial repair facility in Malaysia is it required by regulation or law to have a qualified electrician on the staff? 



 Hi Colin,

Thanks for the email. In our country it is not necessary to be qualified in order to do the job. Many of the wiring men who fix home and office electrical stuff do not have any of the qualification. Most of them got the experience from the Master (first they lean as an apprentice). However if they are dealing with building Maintenance then they may need one.

Best regards,


Hi Bailing,

From the service manual I see the type of IC 201 & IC 601 are different from the actual on the board. In the manual the IC 201 (MCU) is of type 3P863 while on the board you could see it is not the same ( look at the attached photo ). In the manual the IC 601 ( Power PWM Control ) is of type 6S0765RC while again on the board it is not the same ( see the photo ). Do you often experience the difference between the manual and actual condition? Or the previous repairman might have changed them?

It is hard to say as Monitor with the same model could have many different version. In your above case, i have actually seen both types of part number in the same model of Monitor.

Another interesting thing is that I often see a kind of switch on the mainboards of CRT monitor ( see the photo ), Does it have special / common use? Why the manufacturer uses this kind of switch, which is easy to change position unintentionally?

That switch is to set the horizontal centering (if I’m not wrong) of the picture and it was done in the factory by their technicians.




Hi Arvin,


Can I use a 17” LCD panel to this monitor or a 15” as well.

The best is for the same size. That means 17″ to 17″ and 15″ to 15″

How about the backlight connector?

Some have the same connectors and some do not have

After reading your ebook, I was able to get myself a Flyback tester and ESR meter.

This is the best investment

Can we test the components on board or do we need to remove them to have a better reading?

At the beginning test it off board ( for fly back tester). Once you are good you can always test it on board. As for the ESR meter you can test it on board.

On the 17” monitor, is it safe to change the electrolytic caps of 470uf 35v to 470uf 25v?

You can only replace with the same or higher voltage and not lower. 

Can I give you a suggestion as well, since technology is changing a lot, you could look in starting a WEB BASED CLASS WITH LIVE VIDEO STREAMING. I will surely support this. This will be a great big leap instead of confining yourself on your classrooms. 

That was a great suggestion (in fact i have considered that too) but at this time my time will be more on writing books. After the completion of my fourth book i will write my fifth book and so on.




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  1. Sibe

    February 16, 2010 at 10:42 am

    Can you help me Mr. I'm sorry if i don't have a manner.because I can't speak & Writting english very well..may I know comparison of transistor FU9024N & D 10PF.I have this problem because I din't find it in shop

    Thanx & Regards

  2. admin

    February 16, 2010 at 11:13 pm

    Hi Sibe,

    You may use the D10pf6 to substitute for FU9024N. You need to check on other components first before putting in the transistor.


  3. JISHU

    May 11, 2010 at 4:00 pm


  4. admin

    May 12, 2010 at 8:15 am

    Hi Jishu,

    Sorry i have not come across such problem before. First is the output voltages from the SMPS good and stable? Sony Tv are a bit sensitive. Even if the vertical IC output have dry joints, the power LED also flashes. Try check for dry joints in the board.


  5. rolito

    October 16, 2010 at 11:06 am

    can you help me with my epson printer power supply.. when you plug it .smoke is produced from the board??? can you tell me if what is the problem pls....

  6. admin

    October 16, 2010 at 8:35 pm

    HI Rolito,

    You need to check and see as all components could have a chance to produce smoke if there is any short circuit. Pay particularly attention on the resistors.


  7. saqib

    November 7, 2010 at 8:09 pm

    I have a switch mode power supply, there is an inductor just after transformer and this inductor is making noise like (tick tick tick) and my machine is not turn on. what should i do?

  8. admin

    November 8, 2010 at 3:22 am

    Hi Saqib,

    The sound should be from the main transformer. The power chirp problem could indicate there is a problem in shorted component in the secondary side. It may be a shorted secondary diode.


  9. Yusuf

    October 19, 2011 at 5:10 pm

    Hi mr.Yong

    First of all, I'm a newbie. I mean a real newbie with virtually very little field experience in electronic repair. So I hope you're not bored with me asking what few people might say, stupid questions. I have a problem with my lcd monitor, Acer AL1917W. First the display won't kicked in after I return it from standby mode. I turn it off and on again & the display seems to kicked in once again. Later, I have to switch it off and on again just to get the display appearing normally. I'd noticed that the screen somehow darken on half of it when the problem occurs. Now the monitor just keep on going black after its turned on with the green light stayed lit. Oh and btw, my lil brother has the exact same model lcd monitor with the exact same symptoms. Could you please enlight me on how I could done the repair myself?

    Any advice would be much appreciated.

    Best regards

  10. admin

    October 24, 2011 at 12:39 pm

    HI Yusuf,

    Most probably the output voltages not stable. Check all the filter can and make sure no bulged e-cap and all the output voltages are good.


  11. vinny charagu

    March 12, 2012 at 9:09 am


    • Jestine Yong

      March 13, 2012 at 3:12 am

      Hi Vinny,
      Sorry no info o that IC.


  12. vinny charagu

    March 14, 2012 at 4:38 am

    thank you...Mr YONG. ...my laptop HPG61 is not switching on but the power indicator is flickering....what could be the problem?

    • Jestine Yong

      March 14, 2012 at 8:47 am

      HI Vinny,

      It could be the power adapter have problem. Check to see how many volt?


  13. vinny charagu

    March 14, 2012 at 11:16 am


    • Jestine Yong

      March 15, 2012 at 10:30 am

      Hi Vinny,

      You may need to check if the video detector and the video IF section have problem or not.


  14. vinny charagu

    March 14, 2012 at 11:25 am


    • Jestine Yong

      March 15, 2012 at 10:16 am

      HI Vinny,

      I do not use digital multimeter to test transistor or diode because they are not accurate. I only use analog meter but all the testing details I have compiled into the Testing electronic components ebook


  15. vinny charagu

    March 16, 2012 at 5:29 am


    • Jestine Yong

      March 18, 2012 at 6:35 am

      HI Vinny,

      Sorry no info on this. I suggest that you search the web for mobile phone repair.


  16. vinny charagu

    March 17, 2012 at 12:20 pm

    hi jestine my gld tv displays wrinkled words at the bottom of the screen they are not straight pls help

    • Jestine Yong

      March 18, 2012 at 6:39 am

      HI Vinny,

      Please send to me a photo.


  17. vinny

    March 18, 2012 at 11:45 am

    via which link should i send the photo... can isntant heater heat water when the water pressuer low......

    • Jestine Yong

      March 20, 2012 at 8:44 am

      HI Vinny,

      Send to jestineyong(at)electronicrepairguide.com as for the heater so I do not repair instant heater.

  18. vinny

    March 27, 2012 at 10:40 am

    thanks so much mr jestine...i cheacked the defletos and one was loss and thats why the picture was in such a problem....i have received another tv problem..what would you suggest i do to a TV that i touch the circuit on a live are and a neatral area with a finger applied silver and the tv switchs on...i have tried to fix several capacitors but the are getting extrimely hot and the TV is not switch.....however the TVs orginal problem was that it could stay for about 2 hrs with out swicting on..thankyou.

    • Jestine Yong

      March 27, 2012 at 10:38 pm

      HI Vinny,

      Thanks but I don't understand the complaint of the TV-could you elaborate?


  19. vinny

    March 30, 2012 at 8:27 am


    • Jestine Yong

      April 1, 2012 at 9:47 am

      HI Vinny,

      I guess you are referring to optoisolator IC. Do you mean when you power on the TV, B+ voltage came but then drop back to zero volt?



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