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Repaired BenQ FP93V 19″ LCD Monitor
By Jestine Yong on October 14, 2008
The complaint of this BenQ FP93V 19″ LCD Monitor with P/N number 9JL1J72-VWM was no power. As usual have to check primary side first and found that four components have problem. It was a 2 ampere main fuse, .22 Ohm current sense resistor, power FET P7NK80ZFP, and PWM IC 1200AP40. Since i do not have the part number for the power FET, K2645 was used instead. After fixed in all of the components and power “On”, the LCD Monitor came back to life again. The monitor is now under burning in test and should not have any problem with substitution number. In fact i have used that part number to substitute into many different types of LCD Monitors. Here are the photos :
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kevin gibson
November 11, 2011 at 1:04 am
Hi Jestine... Back again..I have tried the light bulb test after replacing the usual components also have replaced the optocoupler, the TL431 and two YG902C2 high speed rectifiers still no luck..Still may be a short in the power tranformer as you mentioned earlier...Back to the light bulb test we have a different story using a 60 watt bulb the light briefly goes on then off, wait a minute try again same occurs..
Thanks again
Kevin
admin
November 11, 2011 at 1:46 pm
HI Kevin,
Since you have checked all the components in the power side then i guess the power transformer could have fault. Before that try replace the power ic and retest. By the way what is the supply voltage to the power ic?
Jestine
Balu
December 15, 2011 at 7:58 pm
Dear Sir,
My LG Flatron LCD Model No.W1942S is getting shutdown within half an hour working. Still the blue standby light will remain on. I had replaced all the capacitors except 0.47mfd/50V. But,there is no change in the status. There is heat build up on the whole power circuit board. Please advise.
Thanking you in advance,
Balu
admin
December 16, 2011 at 7:13 am
Hi Balu,
If all check to be good then suspect one of the back light has weaken. Before that make sure the high voltage transformer does not have dry joints.
Jestine
vinicius
August 18, 2012 at 1:37 pm
Hello friend .. Can I replace the 1200ap40 at 1200p60? what do you think? Thanks!
Jestine Yong
August 18, 2012 at 10:23 pm
Hi Vinicius,
I have not try that but 1200p60 can be replaced with 1200p100.
Jestine
Barbaros Türkyılmaz
November 3, 2012 at 8:29 am
2-3 working frequency is changed, the monitor goes blank after 2-3 seconds the image goes blank again. I could not find the troubled part.
Jestine Yong
November 3, 2012 at 9:45 am
Hi Barbaros,
Have you check the backlight and the high voltage transformer?
Jestine
Barbaros Türkyılmaz
November 6, 2012 at 3:18 am
hi Jestine
I checked yes
Khonyot
December 11, 2012 at 7:25 am
Hi,
I already replace the component P7NK80ZFP with K2645 for my ACER monitor but within 15 seconds it burns and standby LED is not on at all.
Is there another replacement for P7NK80ZFP than K2645 ?
Someone advice me to use FS7UM or SSS7N90, could it ?
Thank's
Jestine Yong
December 12, 2012 at 7:10 am
HI Khonyot,
Then try sss7n90 but before that make sure no other bad components in the surrounding circuitry.
Jestine
Simon
December 15, 2012 at 8:43 pm
Hello Jestine
First of all, Thank you Very much!
There are not a lot of people like you, helping other people to Repair something, to learn something!
So i am also doing a little repairs as my hobby. I like to learn more about Power supplys, etc.
Actually ive done a lot of repairs, but with this one i have problems!
I am out of ideas....
I Got a BenQ 48.L1G02.A00 Power Supply here, which is not working right. (Those benq`s.. oh la la)
The Monitor switches on, shows the picture, after 2-3 seconds it turns off again... Normaly, i think, this is backlight issue... What i dont understand, is, the monitors LED is still green, on, after the CCFL is off.
But if i Light with a Flashlight in to the TFT, i cannot see anything, all blank!
I tested all Voltages, ive Got 3.3V 5V and 18V. I testet with the oscilloscope, all stable and no Ripple, so also the condensers should be fine. If the Backlight turns on, on startup, the 18 Volts sink to about 15 to 16 Volt. I think this is normal, or isnt it? Then if got 2 Lines coming from the LVDS Controll panel, I think its two times +3.3 Volt, if the Power switch is pressed. This is ok, and stays on high / 3.3Volt, even after the picture is gone. For me this means, the Controll board is still saying lets go. I already resoldered the HV transformers, the 7505 Transistors and Fets. I also testet the 7505 for shorts, negative. I then replaced the 7505, because i think its possible that they fail, during the load cycle, negative. One of my questions: How to check the HV Transformers? How to Check the CCFL bulbs? On the Board there is a TI TL1451A, PWM controller wich controlls the background light. As i know they have a two chanel Feedbak cirquit, which lets the Controller know if the two Cirquits are working, otherwidse it switches of. How can i check if the 1451 is switching off my backlight? Actually i checked Pin 10 Out2 and pin7 Out 1 with the osciloscope. pin7 / Out1 Generates a nice and smoot square wave during 2-3 seconds till it stops. Pin 10 / Out 2 generates the same square wave for about 1/2 to 1 second, then it goes to continous high till it stops.... Is this the problem? Is the TL1451A Faulty?
Thanks so far, in advance
Grreetings Simon
Jestine Yong
December 17, 2012 at 9:04 pm
Hi Simon,
The inverter ic tl1451 is very robust and you need a scope to check on the output. In your case you need a powerful torch light to shine on the display. Sometimes the display too dim and you really need a good backlight to shine on it. Check the hv transformer with your ohmmeter and both the transformers should show almost the same ohm in primary and secondary side. We can check the backlight using backlight tester or through comparison method (by using another good working backlight). If this model is using the c5707 and the P-channel fet then you should check all of it and check also for bad tuning capacitors located nearby the hv transformers.
Jestine
Tarsem Bhardwaj
November 19, 2014 at 8:19 pm
Power FET P7NK80ZFP is not available. Pl. suggest the alternate FET
admin
November 20, 2014 at 2:09 pm
The equivalent part number is at the 3rd photo
Jestine
Markuz Zericci
February 4, 2015 at 12:15 am
I have replaced these parts, but alas, the powerboard is still dead.
I was wondering if i could swap out the powerboard for another i have on hand, but i can't seem to find the pinouts for this board.
Do you happen to know what the pinouts are for the black connector that has 10 pins (connector from inverter to graphics driver board)
Jestine Yong
February 4, 2015 at 4:44 pm
HI Markuz,
Sorry I do not have the Monitor or schematic with me thus I do not have the reference. This this Monitor was repaired back 2008.
Jestine
ahmad
February 15, 2018 at 11:11 pm
hi! Acer AC711 crt monitor that came dead to me i have checked it and found that one power mosfet p7nk80zfp, and tl3842 oscillator ic were shorted i replaced p7nk80zfp with k2645 and the oscillator with same part number i test it with series bulb. the bulb goes on and off. then i power it on for a few seconds the led glows with orange color. i thought all is well and i packed it again. after putting back the screws i tested it in series again the bulb glows bright without flicking i opened it again and found that this time only the k2645 was shorted again. plz guide me where is the problem
Mithun Kumar
June 24, 2021 at 9:06 pm
1200ap40 is not available please suggest me with other