About Custom Tax For Test Equipment

Every countries implement taxes so that the Government  will have money to manage and to develop the country. In my country  (Malaysia) for instance,  each test equipment that brought it in, a 10% of tax of the total value of the test equipment will be charged to the buyer. I’m not sure whether it is high for this amount to be taxed or not. I would like to know, how many percent would your Government will tax for importing test equipment? Thanks!

About Shorted Transistor

If you found any shorted transistor in the circuit , chances is very high there will be some other components that may have problem too. Do not directly turn the equipment On after the replacement of the transistor without checking the corresponding components. Dry joints, bad ESR capacitor, leaky diode and etc may cause the transistor to go short circuit. If you take the case of Benq LCD Monitor, the shorted C5707 transistors are usually caused by dry joints in the high voltage transformer or the tuning capacitor have problem and this capacitor have to be test with ESR meter as sometimes it will read good with digital capacitance meter.

So the rule of thumb is to make sure that all the corresponding components are tested good first before putting in a new transistor and power On.  This method also applicable if you found any other shorted semiconductor like diode and IC.

February 2010 Repair Newsletter

If you are a first time visitor to my blog and wish to read my February 2010 repair newsletter that talks about “The Important Of Feedback In Electronic Circuits” then you can click HERE to subscribe to my monthly repair newsletter and you could also read all the previous repair newsletter too. See you in the other side!

Completed Another Basic Electronic Repair Course

This was my second course for this year and it was attended by 8 participants that came from various companies ranging from major newspaper press to building telco tower company. The course went smooth as usual and from the testimonies given after end of the course seems very encouraging. It met their requirements because i started the repair course from very basic and at the end of the third day, they could perform  the repair work. Usually those who came for the course were either Technicians, Maintenance Executive, Hobbyists or Engineers but this time there was a General manager! Okay, here are the photos taken during the 3 days repair course:

 

 

 

 

 

Electronic Repair Questions/Answers And Testimonials-Part 48

Hi Jestine,

 

Thank you for the reply I appreciate it, I bought your ebook to help teach my daughter about fault finding & have to say it is 1 of the best & easiest to read books that I have come across,

Best Regards: Andy

 

==============================

 

Hi Allers,

hi there jestine thanks for all your good e-books im still beginner on tv re-pair i bought all your e-books .

Thanks!

.i have a tv with no hi voltage on flyback ..all voltage after smps is ok ..i have check flyback primary with dick smith tester i have 7 lights ..i read your artical about check wave form to base of hot ..i have no scope is there another way to check .

The best is to use scope as meter would not give a good answer.

.i have check all small transister find ok all caps with esr meter ok check all resister but no volts on the high output the heater light does not light up as well i change flyback from another working tv same problem im stuff please help tv model FINESSE UTSAV FN3780 ALSO I CHANGE THE HOT AS WELL NO Luck THE B+ voltage is 110v on flyback and on middel pin of hot (horisontal transister)please help thanks

Since there is 110VDC  to the flyback then i guess it could be a missing HOT base waveform.

Have a good day!

Jestine

 

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Hello Sir Jestine, good day I have a question you, how to test this STR6656 five pins if good or bad?

Sio

 

HI Sio,

Power On the set and test the supply input voltage and output waveform. The best is to direct replace the power IC and retest. Before that make sure all the components are tested good first.

Jestine

 

============================

 

HI Kristjan,

What kind of meter do you recommend to buy
for testing MOSfet(what is the meter that you use
for testing in 10Kohm range)?

Sunwa or any branded meter that have the x10 k ohm range.

Only 10Kohm range is needed,
if meter goes beyond 10Kohm range,
then that meter in not suitable for testing
(MOSfet)?

Don’t get the  100K ohm range because the voltage in the meter is not high enough to accurately test the Mosfet.


Jestine

 

===================================

 

Hi Jestine

 

You are in the way to make me somebody from nobody your practical newsletters and valuable guids are taking me to the right track to be profisional electronic repairer.

I recived advanced electronics diploma and took training in private electronics workshoop but I was furstrated by what I see from most electronic repairer : try & error fault finding, which is time consuming & tedious, not progrsssing from year to year: interms of their scop of techinque, methodes of fault finding , missmanagement of their time & being stagenant in the same amount of income from year to year.

 

Seeing this I was doing only satellite dish installation in Ethiopia to earn my living. But after your incurraging & practical e - mails I started  repairing  boldely electronic equpements I am becoming familier with printed circuit bords & their most frequent faults, like eliminate cracks by soldering leadpoints cleaning the circuit board. I also started to open TV cover to check weather it is minor problem like fuis, switch,this is my begning ! 

 

You lead me to the right way to becoming profisional electronic repairer. If I spent my time purposefully towards my goal and follow your guid there is no resion that I will not be profissional eelctronicrepairer . After your e - mails I am complitly different person than befor you began making me rich. I am also encurraged to buy your E- books.

 

Let your e - mails dont depart from me.

Thanks Jestine. 

 

Henok berhanu.

 

From  Ethiopia

 

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I believe I have come to the right place at the right time. I have read some of your messages on your website and I am very much eager to get going. A few questions.

1. How can I start off testing all the basic components and then start repairing? Is there a basic step by step instruction you are using?

 

HI Othello,

Thanks for your email. Start with this ebook first Testing Electronic Components. Once you are good in testing electronic components, in fact you can start the repair work. Next steps would be getting either the SMPS or the LCD Monitor repair ebook.
Along the way, if you have any problem in electronic repair you can always email me for support!

Have a good day!

Jestine

 

====================================

 

My grandson picked up a powered subwoofer at a yard sale….it had a blown fuse.  It was labeled

2 amp….but before I could inspect it, he threw it away.

My question is:

Would a 100 watt amplifier inside the speaker use a quick blow or slow blow type of fuse? 

Glenn Normand

 

Hi Glenn,

Thanks for your email. If the sub woofer is using the switch mode power supply then install a slow blow fuse and if it using linear transformer then use a fast blow fuse.

Jestine

 

===============================

 

HI Julien,

1- When you replace a capacitor in a power supply, is there a maximum voltage above the original capacitor’s voltage. For example, if the original capacitor is 1000uF 10V and I replace by a 1000uF 35V … is 35V too much?

The best is to use a voltage that is slightly higher like 16 volt. A higher volt would cause more and have less space for installation.

2- When you replace a MOSFET in a SMPS  or the inverter circuit by another MOSFET but different part number…what are the most important things you need to check on the datasheet to make sure the replacement part is ok? By the way, I already know that I have to check for NPN or PNP type…

For mosfet, you need to check the voltage, amp and watt and make sure the ohm value is not too high or too low.

3-Do you know how to repair the vertical lines on LCD panels considering your rubber trick thats in your book wont work in that specific case?

No, because at the moment i have not heard of anyone that can joint the contact.

Thank you very much for sharing your knowledge … and if you are stuck with a problem, don’t hesitate to ask me because maybe I can help!

Okay no problem!

Jestine

 

==================================

 

Hi Paul,

If the MCU doesn’t send  any power on signal to power supply or inverters what do you normally do? (sometimes there’s not even remote diode lit on the front TV panel!!!)

First, the MCU is programmed to run if it received supply voltage and some important signals like the H/v signals. If the MCU program or the MCU itself have problem, it will not output the on signal. You can either reprogram the MCU (if you have the programmer) or replace with a MCU that already have program in it.

Do you suspect MCU to be bad or EEPROM or FLASH memory to be faulty?

From experience, it is usually the MCU.

Is it best in this case to replace whole main board or something else?

If you could get the MCU with the program and is cheaper than the mainboard then replace only the MCU.

 
Jestine

 

==================================

Your Name: Martin Tan
Message: Hi,Jestine

I stumble on your site when googling for line trans for pc monitor.I have a few monitors which I like to repair.It is sheer waste to throw away such techonology.

I suspect they all have line trans.problem.Your site has given me hope in my persuit.

I want to congratulate you for your wonderful site.

Keep up the good work.

 

=================================

 

Hi, I’m also wishing you all the blesssings.

sorry if i cant reply promply, for i am bussy with my business.

i would like to ask you what’s the pros & cons of being an authorized service center.

and what brand would be the best.

 

thank you!

 

NAM

 

 

HI Nam,

It could be any brand and not easy to become authorized service center.

You need lots of staff, test equipments, good work place plus security, commitment to work during holidays and etc.

The benefit is, you will be getting lots of first hand information from the company and you will not lack of anything to repair thus you are guaranteed to have continuous repair work.

Jestine

 

==================================

 

good day sir jestine! i just wanna ask you this kind of problem i encountered.. this is a sony tv model KV-2168MT. there is an indicator power signal but if we turn on it will go bach to standby mode. how can we determine what causes this kind of problem? we used a new jungle IC but still it doesn’t work. what are other options we shall do to fix this problem? please do help me. thank you.

 

HI Rogelio,

Is the CPU receiving the right voltage. Sometimes a bad EEPROM or CPU could cause such problem. Make sure the HOT is not shorted or leaky.

Jestine

 

================================

I jestine Yong wath is the best surfacemount removeal tool you can reccomend thank you

 

HI Dwight,
I just use normal rework station and it can do the job well.

Jestine

 

==================================

 

having trouble with some psu’s in smaller lcds like the nec 1550v still learning the basics can you give me any tips i have 3 units that do not power on but the power led flashes green somewhat rapidly and then a fourth that works fine but i have compared nearly everything save a few components im not sure i can test with my multimeter.

 

Hi Neo,

Is the output voltages from the SMPS good an stable? If yes then suspect a bad MAINBOARD. If no then suspect either the inverter board components shorted that pulled down the SMPS or the SMPS itself has problem.

Jestine

 

================================

 

Hello Mr. Yong,
I have a BenQ FP71G + LCD monitor that has the following problem:
    -do not light the lamps backlight.
I read his guide for the repair of the LCD BenQ FP71G + and I replaced all the components you mentioned in the Guide (Pico fuse, transistor C5707, FQU11P06 FET, 1000UF 16Volts E-cap and 22 UF 250V polyester capacitors).
The lamps are lit but only x hours a couple of seconds, this may depend on what type of problem?
Please give me help, I can not go further.
Thank you and I send my sincere greetings.
Alipante

 

HI Alipante,

If the lamp for a split of second then check on the backlight because a bad backlight could cause such problem.
Is all the voltages from the  SMPS  are good and stable?

Jestine

 

============================

 

Hi Sir..

 

this is my first mail. i need some help  from you.

In my PROVIEW LOW RADIATION CRT MONITOR Blue Colour patch come in center

i need solution about above prob.

 

plz. replay me..

thanking you ..

 

Anand

 

HI Anand,

You need a demagnetizer to remove it if the internal degausser is not strong enough. If it still there after using the external demagnetizer then i guess the crt tube have problem and need replacement.

jestine

 

==========================

 

Hi Jestine,

I have a Sumsung SyncMaster 763mb computer CRT monitor lying around for more than 2 years.

It was discovered having color display problem which could be fixed by pressing the cable near the
connector to the PC. My elder brother cut off the connector but failed in the attempt to properly resolder back
the wires to their pins accordingly, and it was left in the store since then.

I wish to give a life back to the monitor.
I wonder if you have any pin diagrams which could help me identify which wire is to which pin?
I noticed that the cable contains more than just RGB wires. There are several more other tiny wires too!!

Thanks in advance.

Sincerely,

Wong

 

Hi Wong,

It would be difficult  as you need the original cable as reference. the reason for it is because Monitor manufacturers do not use standard color code for reference. Please visit this link to see the pin configuration:

http://en.wikipedia.org/wiki/VGA_connector

The most important signals in CRT Monitor are the RGB, Horizontal and Vertical.

Jestine

 

================================

 

Hi Jestine,

Hope you are well.Just a quick email to ask ,when i am testing voltages in an lcd monitor do i need to have it connected to my pc or can i test without hooking it up to my tower.

Thanks

regards

Shaun

 

HI Shaun,

The best is to connect to the computer otherwise the voltages may drop to half if no signals coming in from the computer.

Jestine

 

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Electronic Supplier From USA

Found another electronic supplier from USA-ABRA Electronics. I have been compiling electronics supplier website and nowadays getting hard to find new electronic supplier. If you know of any electronic supplier website please do let me know and i will put it into the electronic suppliers category in this blog for your easy reference-thanks. Please click on the above photo to visit the website.

What is Arc Flash?

If you repair CRT Monitor or TV, i believe you have seen before the blue arc from the anode to ground. If you need to understand how this arc happen please click on the photo above.

Intel 45nm Chip Factory

Pros and Cons Of Being An Authorized Service Center

Recently got an email from ERG member about the pros and cons of being an authorized service center and this is what he wrote to me:

I would like to ask you what’s the pros & cons of being an authorized service center.

and what brand would be the best.

 

thank you!

 

NAM

 

And here is my answer to him:

 

HI Nam,

It could be any brand and not easy to become an authorized service center. You need lots of staff, test equipments, good work place plus security, good location, commitment to work even during holidays and etc. The benefit are, you will be getting lots of first hand information from the company about a particular products in term of schematic and related info and you will not lack of anything to repair thus you are guaranteed to have continuous repair work. My company was a former authorized service center for ALR computers but they already closed down.

 

Certain repair companies are authorized service center for many major brands in the market. If you are or had been to any company authorized service center before, i would like to hear your story-thanks!

What Could Cause A Transformer To Burn?

 

Whether you are dealing with Linear or Switch Mode Power Transformer, I’m sure you have came across a burnt transformer  before. The question is, what could have cause the transformer to burn (shorted primary winding, bad smell from transformer internal parts, open primary or secondary winding and etc)? From my experience, below are some of the possible causes:

1) Lightning strike

2) Power Supply Design fault

3) Low quality of the transformer used

4) Shorted components in corresponding circuit (primary side)

5) Shorted components in the secondary side

6) Decayed glue used in surrounding circuit.

If you know of any other way that could cause a transformer to burn please share your comment -thanks!

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