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Repairing BenQ 17″ LCD Monitor
By Jestine Yong on January 31, 2008
I came across a common fault problem in BenQ 17″ LCD Monitor. The problem is have power but no display. Once you has opened the LCD cover, check the pico fuse for open circuit (very common), the push pull transistors C5707 for short circuit and the Buck royer circuit p-channel fet FQU11P06 also for short circuit too. For your information, if you can’t get the FQU11p06 you can always use FU9024N as a replacement. Resolder all the high voltage transformer pins and replace the components above and I’m sure you will bring back the life of this BenQ 17″ LCD Monitor.
You may go to this fairchild semiconductor website to download the spec of the FQU11P06 P-channel FET.
http://www.fairchildsemi.com/ds/FQ/FQU11P06.pdf
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sanah
May 22, 2011 at 3:33 pm
i have benq lcd monitor and problem is after a few secound screen coming black i meen after few secound no display atometic gone display so i chacked the fqu11po6 channel fet, fu9024n tr, c5707 transister every thingthing is fine. i tried many time but i can't repair it so plz can you sugges me how can i fixt it.
admin
May 23, 2011 at 3:19 am
HI Sanah,
Try check or replace the lamp. One of the backlight got problem will cause it to shutdown.
Jestine
sanah
May 23, 2011 at 7:28 am
hi i am sanah, i chaked lamp it is ok but when comes dark screen that time i chaked high-voltage that time no voltage, and fu9024n tr, c5707 transister i replace. so now whats the problem plz help me.
admin
May 23, 2011 at 11:28 pm
HI Sanah,
May i know how do you check the lamp? When it shutdown, is the supply voltage to the inverter ic still present?
Jestine
Diego Piedrabuena
May 29, 2011 at 2:03 am
Primero quiero felicitarlo por este sitio y darle las gracias por su valioso tiempo. Mi nombre es diego, soy de Buenos Aires, Argentina y tengo un monitor Benq FP731 que esta quemando los C5707 Q759 y Q760 y el fusible. Mi pregunta es saber si debo rebobinar los transformadores o algun otro componente me esta trayendo el problema.
Muchas Gracias.
First I want to congratulate you on this site and thank you for
your valuable time. My name is Diego, I'm from Buenos Aires,
Argentina and I have a Benq FP731 monitor that burning the
C5707 Q759 and Q760 and fuse. My question is whether I
rewind transformers or any other component is me
bringing the problem.
Thank you very much.
admin
May 30, 2011 at 3:17 am
HI Diego,
Try compare both top and bottom circuit using ohms range. If there is any different in the ohms value then suspect the point you are comparing have problem. Make sure no dry joints and the tuning cap value is good. This tining cap is locates nearby the high voltage transformer.
Jestine
guru
June 2, 2011 at 5:04 am
hi! iam a electronic technistion ,i realy like your service,i hope may get support for electronics device services.thank you for this service.
NIKOL
June 7, 2011 at 11:04 am
HI YOUNG,IM,NEW AND WOULD LIKE TO ASK YOU SOME QUETIONS BUT DONT KNOW HOW. PLIZ HELP
admin
June 7, 2011 at 9:48 pm
Hi Nikol,
What is the question?
Jestine
Potter
June 14, 2011 at 10:47 pm
Hello, I have a problem on BenQ G700AD 17" LCD Monitor, this monitor can not be turned off with the on/off, when using the computer to display images in 30 minutes, and now can not display the picture again? Can I replace components such as the above? please help me .. TNKS.
admin
June 15, 2011 at 7:36 am
HI Potter,
Try check if all the output voltages are good and stable or not?
Jestine
manoel anxo leston gallardo
July 13, 2011 at 5:04 am
En el monitor BENQ Q7T4 SE ME HAN SOLTADO LOS CABLES DEL BOTON DE ARRANQUE, HE BAJADO EL ESQUEMA PERO NO SE DISTINGUEN BIEN. ¿PUEDE ALGUIEN DECIRME SU ORDEN CORRECTO? GRACIÑAS.
admin
July 13, 2011 at 8:46 pm
Hi Manoel,
Sorry i do not understand your meaning even after i have used the translator. Could you elaborate again?
Jestine
Manoel Anxo Leston Gallardo
July 14, 2011 at 4:01 am
HELLOW,JESTINE:
Ihave a screen monitor BENQ.Q7T4, but it is out of order; the cables in the start button are out. I d'ont know its colors order, can you help me?
It has, I think , about 9 cables each them different color, yellow, red, black,...etc. but, how can I know the correct order?
Thank you very much.
admin
July 14, 2011 at 5:22 am
HI Manoel,
Since my workshop here does not have the same model thus i could not find the answer for you. If i have the monitor with me i could open it up and tell you the answer-sorry.
Jestine
Ricardo
August 3, 2011 at 8:48 am
Hello Jestine Yong,I would like help on the following problem.
I am not able to identify the C5707 in the circuit and what is its reference
thanks
Ricardo
August 3, 2011 at 9:50 am
Hello,y must repair de 4 c5707 or the 6?
admin
August 3, 2011 at 9:44 pm
HI Ricardo,
The word C5707 is printed on the transistor body and it has 4 of them. The reason you check or replace it is because most of the time these transistors have problem.
Jestine
bijoy
August 4, 2011 at 11:45 am
hi jes
compaq 17"crt monitor tick tick sond some time power led blink
bijoy pv india kerala trissur
admin
August 4, 2011 at 9:30 pm
HI Bijoy,
Try the link below:
http://www.electronicrepairguide.com/testing-flyback-transformer.html
Jestine
Moises Sitoe
August 18, 2011 at 7:45 am
peço ajuda ,tenho dois monitores HP L1908W e HP L1710 ,ambos com mesmo problema, quando ligados mostram dados e 1 minuto depois perde imagem, ou melhor,nota-se que a luz na tela apaga-se
admin
August 19, 2011 at 1:03 am
oi,
Certifique-se de não inchou e não cap-and juntas secas no transformador de alta tensão. Se tudo verificar para ser bom, em seguida, uma da luz de fundo pode ter problema.
Jestine
mustapha
September 1, 2011 at 11:47 am
first thx jestineyong for this form
my problem is my lcd hp L1755 goes of afer a second
i cheeked all transistors 2SC5707 and the transistor mosfet J598 AND all cap ;all is good so where is the problem
i forget the oscillator TL1451 had VCC 12V
THX IN ADVANCE
admin
September 1, 2011 at 8:09 pm
HI Mustapha,
If all check to be good then suspect one of the backlight have problem.
Jestine
Bro. John Bosco Kidega
September 16, 2011 at 3:00 am
Can you help me please. I have a Dell E153FPb - made from China. It has a Benq circuit board. The problem is when I power the monitor the disply is not seen clearly (very faint). What could be the problem(s). Thanks.
admin
September 19, 2011 at 6:03 am
Hi John,
It could be missing supply voltage to the inverter ic. make sure the pico fuse (if there is one) did not break and no shorted components ( expecially transistors) in the inverter circuit.
Jestine
hans
September 24, 2011 at 12:15 pm
hi justine,
i have a BenQ W1508, when i plug in the power cord, the power light and backlight are blinking rapidly at the same time continuously. i opened it and i see no burnt components and no bulging capacitor either. do you have any rough idea what component/s has a problem?
manufactured year is 2008, so it is not that old.
thanks
admin
September 26, 2011 at 3:31 am
HI Hans,
First is the output voltages from the power supply good and stable?
Jestine
Ajal Thapa
September 30, 2011 at 9:28 am
My lcd gets off while i used it for 10 minutes .....
what can i do to solve this problem
admin
October 1, 2011 at 2:19 am
Hi Ajal,
It can bad e-caps, dry joints in high voltage transformer or one of the back light have problem.
Jestine
Felix Orji
October 31, 2011 at 10:17 am
nice work
Soroush
November 4, 2011 at 7:49 pm
Hi,
I have LCD monitor BenQ Model: ET-oo26-B
Problem is turn ON for about 1 second and shuts off, and screen is black, , I changed all capacitors but no difference, any suggestion very appreciate, thanks
Regards
Soroush
Soroush@FaxEngineer.ca
admin
November 5, 2011 at 2:38 am
HI Soroush,
One of the backlight could have problem. Before that make sure no dry joints in the transformer.
Jestine
Oxize
November 6, 2011 at 10:27 am
Hi Jestine,
I have an BenQ FP937s+ for a while now as a 3th monitor. But the last year, its going blank from time to time.
When i blow air into the monitor with my mouth and i turned the power off, and i turn it on again, it does work for a while. Sometimes a whole day, sometimes a few minutes.
Does this mean there is some overheating problem? Which element or piece of chip could do this?
Do the fairchild circuit diagram works also for me? If not, could you send me one for the BenQ FP937s+?
Hope to hear from you soon.
Thanks!
Oxize
November 6, 2011 at 12:19 pm
Oh on a sidenote. The buttons are working good. Its just that the screens goes blank from time to time. I need to put off the monitor and wait for a few minutes and then i can turn it on again.
Sometimes it takes 3 or 4 times to put to monitor on/off to work for a long time.
Can this problem be dry joints or some chip which is overheating?
admin
November 8, 2011 at 12:11 pm
HI Oxize,
Sorry i9 do not have the schematic diagram. In your case it could be dry joints or even bulged e-caps on the power supply section.
Jestine
nuno
November 14, 2011 at 10:20 pm
can you help me ??
i have a lcd monitor benq Q7C3 it´s turn (led green ) but no image , i just substitut de 4 (C5707), 2(Fu9024N), capacitor 1000uf/16v and 470uf/35v and the problems presiste (no image) the resistor R513 is OK and de bobines is aparently ok
can you help me please ........... my email : nunogfaria@hotmail.com
thanks
Mac
November 15, 2011 at 1:19 am
Hi Jestine, I have two HP1704 (BenQ M170EG01) monitors with similar faults. They both power up and I get a picture, but it disappears after about 15 seconds. I have tried to shine a light on the LCD to see if the picture remains (once the tubes turn off) but I can't see any signs of one. Once the monitor starts and picture is visible, there is an audible hissing noise from the inverter transformers. It's not that loud, but I can hear it. If I apply pressure to either one, the noise increases. I have replaced all the electrolytic caps, and this has not cured the problem. I am wondering if the problem is the CCF tubes, can you suggest how to test these or determine what the problem is from here onwards. I'm an electronics tech of 35 years and this LCD technology is new to me and a steep learning curve.
Mac
November 15, 2011 at 1:44 am
Some more information to add to my last post.
I have also checked the board for dry joints, especially around the transformers etc. The voltage rails appear to be steady.
Between the last post I made and this one, I tried something which I had read on another forum. I reduced the brightness from 100% down to 50% and the picture stays on. I then increased it to 80% and it still stays on. Then I tried 90% brightness and after 15 seconds the picture disappeared.
This leads me to believe there's a problem in the inverter section. At high brightness it is shutting down on an over-current sense. Do you think this is caused by the lamps? I am also wondering why the HV transformers hiss the way they do.
admin
November 15, 2011 at 12:36 pm
Hi Nuno,
Is there supply voltage to the inverter ic?
Jestine
Mhel
November 15, 2011 at 2:20 pm
Hi Mr. Justine Young
I have here a BenQ FP556ms 15 inches LCD, my problem is when I turned on my LCD it power on and display No cable connected and for few seconds the screen turns white, if you try to turn it off and on again it's still white but try to rest the lcd for an hour and turn it on the No cable connected appears again and the white screen again. I have check all the voltages from the primary side and secondary and checks good 12v and 5v there. can you please tell what seems to be the problem with my LCD
Thanks a lot in advanced
admin
November 16, 2011 at 1:45 pm
HI Mac,
There could be few possibilities like bad ccfl, bad high voltage transformer, bad ballast cap and faulty lcd panel. First you need to make sure the inverter ic is getting supply voltage when the monitor is set to full brightness. If you did not get supply voltage the mainboard MCU may have problem. By the way, try gently knock on the high voltage transformer to see if the sound will go away or not.
Jestine
Tony denson
November 18, 2011 at 6:04 am
Hi Justine, I've just fixed a 17" benq i rescued from the nature strip following your tips about checking c5707's and resoldering hi voltage txformers.
Thanks very much Tony
nuno
November 18, 2011 at 9:35 am
Hi Justin
IC751 ( TL1451ACN)
8: 15v
9: 0v
10: 15v
11: 0v
12: (-0.17v)
13: 0,9v
Thnx
admin
November 18, 2011 at 2:38 pm
HI Tony,
You are welcome.
Jestine
admin
November 18, 2011 at 2:45 pm
Hi Mhel,
You need to check the supply voltage to lcd controller ic. No supply to the lcd controller board could cause white display.
Jestine
admin
November 18, 2011 at 2:52 pm
HI Nuno,
It seems like there is no supply voltage to pin 9. You may need to trace it backward to see if there is any bad components.
Jestine
nuno
November 23, 2011 at 10:11 pm
Good evening justine
Thanks for the tips that your site has made available to repair my monitor benq
After replacing them:
4x C5707
2x FU9024N
in case:
6x 470uF \ 35v
2x 1000uF \ 16v
still no picture and then to measure the IC as you mentioned and have posted the voltage, I noticed that was behind the MS 3A 125v (fus.) there would be wide open at the final resolution of the problem
Thanks for the help provided
Nuno Faria
Oxize
November 25, 2011 at 6:10 pm
Hi Jestine,
I check my BenQ FP937S+ on dry joints (http://img690.imageshack.us/img690/1026/joints.jpg). I couldnt really find any dry joints on the power supply circuitboard or the VGA/DVI Circuitboard.
The only thing i saw was 2 slightly bulged Elite E-caps (http://img811.imageshack.us/img811/5647/ecaps.jpg) on the power suppy circuit board. Could give these slightly bulged ecaps the problem that my monitor gives a blank screens after a few seconds or minutes? I stated this in a few messages back (check above).
For the rest the DVI/VGA circuitboard was verry clean and looked good.
This is how the Power Supply circuit looked like in general: http://imageshack.us/f/560/psucircuit.jpg/
I hope it are those 2 e-caps. Awaiting your answer 🙂
Oxize
November 25, 2011 at 6:18 pm
Btw Jestine, Those 2 ecaps are Elite 1000uf 16v. Do you know where i can buy those?