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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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sapto (Indonesia)
April 18, 2010 at 9:35 pm
Help me, LCD Monitor BenQ Q7T4, S/N ET7C508207SL0:
- Blank
- No Led
What's Problem?
Thank's!
from Sapto;
Bantul, DI Yogyakarta, Indonesia
buddhika
December 7, 2020 at 5:03 am
Thank you. I have 2005 led monitor
admin
April 19, 2010 at 4:23 am
HI Sapto,
If there is not output voltages from the SMPS then i guess you may need to test out all the components in the smps side.
Jestine
Graham
May 1, 2010 at 12:28 pm
Hi Jestine, maybe you could point me in the right direction ! My BenQ FP91G+ has just died. First sign was the brightness menu popping up on the screen a couple of times then a couple of days later the monitor would not power up. It shows NO green light, nothing. On the main power board I've checked the main fuse & have the correct voltage both sides. Not sure what to check next...There is a 11pin output socket on this board and I am getting various voltages on some of the pins but I'm afraid they don't mean much to me! Any help would be appreciated.
admin
May 1, 2010 at 9:19 pm
HI Graham,
In your case it could be a bad MCU in the mainboard. Before that you must check that the SMPS have good and stable output voltages. Getting voltages and getting the right ans stable voltages is two different things. I'm not sure about this model output voltages but generally LCD Monitor voltages should be about 12v, 5 v, 3.3 v or even 2.5 v.
Jestine
Enrique
June 12, 2010 at 11:49 am
Hi
I have a problem with a Benq monitor FP91g + and check all the capacitors, I have the basic tensions inverter 15V, 3.3 V and 5 V, the monitor turns on a few minutes and then off completely as if restart until the LED turns off then on again and so on, hopefully I can help you
admin
June 13, 2010 at 8:38 am
Hi Enrique,
If the supply voltages to the mainboard are good and stable then most probably the MCU have problem.
Jestine
ktgoh
June 24, 2010 at 11:08 pm
i have a resistor connected to pin8 of IC 1200AP40 burnt beyond recognized, can u suggest any conman value for this resistor..?
main fuse & resistor checked ok..
admin
June 25, 2010 at 6:05 am
HI Ktgoh,
Sorry i do not have the diagram and there is no same monitor model in my workshop thus i can't suggest any value for it. You may have to find a diagram that use the 1200ap ic and then check to see what resistor value connected to the pin 8.
Jestine
Anom
September 5, 2010 at 7:43 am
Dear sir,
I want to ask about my dead old lcd monitor. the brand was i-o data, LCD-A141H. do you have the schematic for this? i think it was power trouble, because no power at all. the fuse is good.
best regards
admin
September 6, 2010 at 10:31 am
HI Anom,
Sorry i do not have the schematic diagram. Is there supply voltage entering the power IC?
Jestine
Graham
October 9, 2010 at 3:10 pm
Hi again Jestine, I contacted you earlier in this post regarding this = "My BenQ FP91G+ has just died. First sign was the brightness menu popping up on the screen a couple of times then a couple of days later the monitor would not power up. It shows NO green light, nothing. On the main power board I’ve checked the main fuse & have the correct voltage both sides. Not sure what to check next…There is a 11pin output socket on this board and I am getting various voltages on some of the pins but I’m afraid they don’t mean much to me! Any help would be appreciated."
I have now replaced both the main power board and interface board. The monitor worked perfect for another 5 days after which there was no power light showing again, nothing ! I replaced the interface board with another new board ( I got a great deal on these boards so I bought a couple of each) and the display worked perfect again until I shut it down and then no power light again, nothing !! I have checked output voltages on the main board and am getting the correct 3.3v & 5v. Checked the control board and all the switches work ok. I am now not sure what to do and looking for any help. Incidentally, I do have all the schematic circuit diagrams for this monitor if that helps. Thanks.....
admin
October 10, 2010 at 9:43 am
HI Graham,
This is real challenging. When you have said you have replaced the power/invert board, mainboard and have checked the front panel switch by right it should have solve the problem.
If you got the output voltages then i do not suspect the power/inverter board. That means it left only the mainboard, front panel board and the wires between the front panel and the mainboard. I suggest that you directly replace the on/off switch and check the cable and retest it again since you have said you already replaced the mainboard.
Jestine
Diamon
October 10, 2010 at 12:24 pm
Hello Jestine,
I have an HP L1740 monitor with no power. The powerboard is an Benq one, the inverter part is also on this board.
I have replaced the FET, PWM IC 1200AP40, opto coupler, transfo from a working HP L1740 screen (the powerboards are the same). All the big resistors on the primary are okay (I have them compared / measured with the working powerboard). After all these changes, the board still doesn't function (dead). I know for sure, that all the parts are good, because the working powerboard is still working).
I don't have a oscilloscopes, so I cannot see if the pwm controller is working. All the electrolyte caps are tested with a ESR device, and are okay.
Do you have any idea what the problem could be ?. Or how I can exclude other parts with a digital multimeter ?.
Thanks for your answer
Graham
October 10, 2010 at 1:03 pm
Hi Jestine, many thanks for giving your time & thoughts about this BenQ FP91G+ monitor fault. I agree it's certainly challenging ! I have tested the operation of the power switch right back to the plug that connects into the interface board and I clearly get a clean on/off reading on my multimeter. If I select the "buzzer" option on the meter I can actually get the small neon to light up, both orange and green, proving the continuity from the plug. You think changing the whole control board might be the best way to go ? That's if I can get one. Could a faulty backlight stop the "power light" and everything else from working ? If I gave you a copy of the engineers schematics etc. for this monitor think it might give you any other idea's ?
Thanks again....
admin
October 12, 2010 at 8:41 am
HI Graham,
Since you have not replace the front control board then you should try it in order to look for an answer. Backlight problem would not cause it to have no power. Thanks for the diagram but i believe it won't help much since you already have the boards for replacement.
Jestine
admin
October 12, 2010 at 8:46 am
Hi Diamon,
Is there any output supply from the SMPS because with power LED not lighted up you may have thought it was the power supply board problem. If it is zero volts on all output then your concentration should be in the power primary side. Makes sure the secondary output diode is not shorted. Check that the power IC is receiving supply voltage and if all components are tested good then try replace the power IC again. In very rare cases, sometimes a new power IC could have problem too.
Jestine
Diamon
October 16, 2010 at 2:09 pm
Hello jestine,
I have solved the problem with the powerboard.
There was a smd resistor that was broken (it had no value any more).
After I had replaced the resistor, the problem was solved 🙂
Thanks for your input.
Simon
admin
October 16, 2010 at 8:33 pm
Hi Simon,
Congratulation!
Jestine
mahmoud
October 26, 2010 at 4:16 pm
hello sir , i have lcd name : ,mirai model : t20018 , its work normaly for a diffrent time's and stop again , but the led still green not change to red , can you helpe me please.
admin
October 26, 2010 at 8:21 pm
HI Mahmoud,
When you said stop again, is there any display, or the display have problem or shutdown with no/dim display?
Jestine
mahmoud
October 27, 2010 at 3:59 am
thank you sir for your respond, stop again mean shutdawn , but you know when the lcd or tv had shutdawn the led giving red ( stb ) but this lcd still green and stop respon from the remot or from the buttons , and we have to leave for a long time and try again then its working and start elc...
mahmoud
October 27, 2010 at 5:46 am
there's yellow led betwen green and red its' given , and when i check the board , nocking slowly at pcp board its working for a second and stop again,,
carlose
October 27, 2010 at 4:30 pm
hi mr jestine , when lcd turn off after 2 second from i puch the bottom , i was Lifting protection from ic in inverter like to put resistor from the timer side to grnd up the capacitor , and the lcd working . is that good ? is there's another way to fix this problem ? thank you for helping me.
carlose.
admin
October 27, 2010 at 8:15 pm
HI Carlos,
To defeat the protection may have some risk. If the backlight have problem and if the protection did not shutdown, there will be a chance for the lcd monitor to catch fire and etc. If possible check first the backlight condition because usually a bad backlight would cause the display to shutdown.
Jestine
admin
October 27, 2010 at 8:17 pm
HI Mahmoud,
Make sure no bulged e-cap and no dry joints in the high voltage transformer. Sometimes a bad backlight could cause the display to shutdown.
Jestine
Mushfiqur Rahman
October 28, 2010 at 2:49 am
Hi,
I am trying to repair ACER 1916W LCD monitor. When I give power to the monitor it's show me the green LED indicator and after sometimes it goes to yellow from green. To repair it I have removed it's metalic cover and then check it's component. Here I see that it's CFL bulb is not getting any voltage. That's why I have thought that may be the high voltage transformer has gone or may the electrolytic capacitors. But after checking that I see they are ok. But if check them without removing from the PCB it shows nothing but if I remove them they show me they are ok. Here I see everything is OK. Then why the CFL bulb is not getting voltages?
Please.. Help me..
Thanks.
admin
October 28, 2010 at 9:39 am
HI Mushfiqur,
The ccfl not working was due to that mainboard did not send an On signal to the inverter IC. If the VGA cable is connected and the POWER LED light turned from green to yellow then this mean the Micro controller (MCU) programs may have corrupted. It is the mainboard problem since the MCU is located in the mainboard.
Jestine
carlose
October 28, 2010 at 2:41 pm
hello sir , mr jestine ,in general , is there a diffrent btween lcd and plasma about eeprom if i have to make a new programe ? and do i need programmer for it like tv ? you know on tv we have to pull up the eeprom and put it in programmer , or in lcd or plasma we can do't with cabel ? please if you can send me theme about that with photo if you can , that will halpe me toooo much please..
admin
November 1, 2010 at 3:01 am
HI Carlos,
Both lcd tv and plasma tv programs can be updated by connecting a usb drive (with programs) in it to the USB port but sorry i do not have such photos.
Jestine
alfie
February 5, 2011 at 12:16 pm
nice information sir..
thanks a lot,,but my other lcd monitor was short on ic 1200AP40.i do not have the part number for this IC, so i have an question for u sir..
what the number IC i must use instead..??
admin
February 5, 2011 at 11:25 pm
HI Alfie,
If possible use back the same part number. You may get one from this website:
http://www.utsource.net/ic-datasheet/1200AP40-1701860.html
Jestine
Geoffrey Pak
June 30, 2011 at 2:20 am
Hi Jestine,
Thank you for your great site. I have a 17" Benq monitor whick blew up the fuse. I think I have the same problem with this. I have changed the 2A fuse, PWM IC 1200AP40, and a FET. I have not replaced a current sense resistor. Can you tell me where this resistor is located? Any other replacement for it?
Thank you and look forward to hear from your advise.
Geoff
Geoff
June 30, 2011 at 2:29 am
Hi Jestine,
Adding more to my previous post, since replacing the three components, I tried to turn the monitor on but still no power. Maybe something else is the problem. I would like to replace the current sense resister if I only know where it is on the board.
Thank you.
Geoff
admin
June 30, 2011 at 7:34 am
HI Geoffrey.
It is located at the power FET and usually it has very low ohm. You can use a small value for replacement but not a bigger value.
Jestine
Geoff
July 1, 2011 at 4:33 am
Hi Jestine,
Just replaced the current sense resistor from another power supply of similar value but still no power.
Any idea what else could be wrong?
Thanks,
Geoff
admin
July 1, 2011 at 4:42 am
HI Geoff,
What value of ohm did you use? Have you check the secondary diodes? Try remove the power fet and retest again.
Jestine
Geoff
July 6, 2011 at 2:04 am
Hi Jestine,
It was a 100ohm resistor. I checked the FET but it is shorted again.
Replaced the FET and now the monitor works. Thank you for your knowledge and guidance. You are agenius !
Regards,
Geoff
admin
July 6, 2011 at 8:19 am
HI Geoff,
Congratulation!
Jestine
Charlie
August 16, 2011 at 9:15 am
This is my new email
Thanks
You' so Helpfull
Thanks again
admin
August 16, 2011 at 9:56 am
HI Charlie,
May i know what is your old email so that i can delete it from my database and update with a new one.
Jestinr
mustapha
September 3, 2011 at 5:55 am
HELLO JESTINE
PLZ TELL ME HOW TO TEST TR FET 2SJ598 . RESISTOR BETWEEN S/D S/G D/G
THX
admin
September 6, 2011 at 7:15 am
Hi Mustapha,
Try this link:
http://www.electronicrepairguide.com/mosfet-testing.html
Jestine
alex
September 28, 2011 at 6:57 pm
he wanted to have these components, price and rule of the payment interests
admin
September 29, 2011 at 8:29 am
Hi ALEX,
Sorry we do not sell components
Jestine
kevin gibson
October 10, 2011 at 3:23 am
hi Jestine....I am in the process of repairing a Benq monitor but i am having trouble sourcing the power mosfet k2645 and the ic pwm 1200ap40 in AUSTRALIA, also is the 2 amp fuse ceramic fast acting or slow blow and for some reason i cannnot find a 2 amp ceramic 20mm long in AUST.
The other part that has failed is the 100uf 450volt capacitor..Any suggestions to a webb site i can obtain these parts..Prefably in aust.
Regards Kevin Vk2ckg
admin
October 10, 2011 at 12:29 pm
HI Kevin,
You can try utsource.net and for the fuse you can use a fast blow fuse but you need to modify to fit in.
Jestine
kevin gibson
November 5, 2011 at 6:42 am
Hi Jestine.. Still no luck on the Benq fp91g replaced pwm and mosfet also .22ohm resistor and 2amp fuse ...Have also replaced the 100u 450 volt electro which was corroded or burnt off on the + leg have also replaced the bridge rectifier 2a 600v which was faulty and still no luck...Cannot see
any other problems in the circuit..Any other thoughts??..
Thanks in advance
Kevin
admin
November 7, 2011 at 9:10 am
HI Kevin,
Now totally no output voltage or have little voltage? If totally zero volt this mean there must be still bad components in the power circuit. Ok now i suggest that you turn on the monitor and check the supply voltage to the pwm ic. See how many volt did you get. Sometimes a shorted primary winding in the power transformer also could cause no power symptom.
If your version of power supply use optoisolator ic and TL431 IC then directly replace it and retest.
Jestine
kevin gibson
November 8, 2011 at 7:49 am
Hi Jestine..Sorry i should have mentioned with the parts replaced including the bridge rectifer the fuse still blows so i haven't got to the stage to check voltages..This version has a PC123 PHOTO-COUPLER and TL431 SHUNT REGULATION
Kevin
admin
November 8, 2011 at 12:00 pm
HI Kevin,
Try connect a bulb inseries with the main live wire to protect the components you have just replaced. Google for light bulb series trick for more information.
Jestine