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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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Bruce Saxby
February 5, 2008 at 8:35 pm
Loved your website, I found it during a hunt to find information on a fault with my own Benq FP71E which starts up shows the symbol on screen and then no picture. I have some training many many years ago but not too fresh on these things (or others now either. Anyway I will have a new look now at the power supply any maybe find something. Your website inspired me and I must say your attitude to help others and improve the general level of tech skills and co-operation is great and to be commended. Its obvious by your contributions on the web and book writing etc. God Bless Ya!
Jestine Yong
February 5, 2008 at 10:07 pm
You are wclcome Bruce!
Have a great day!
Jestine Yong
http://www.ElectronicRepairGuide.com
terry
October 11, 2008 at 5:35 pm
Can you help me please. I have a 17 inch BenQ monitor model number is Q7C4. I turn on the monitor and computer and it starts to fire up. After about 10-30 sec the screen goes black and the front indicator light is still blue. Once or twice I managed to get it going by several attemps at plug out and reconnecting eithr the power lead or mostly the white screen lead.
I have pulled apart the screen but no signs of bolging capacitors or heat stains present on the circuit board. Has anyone else com across this problem?
admin
October 12, 2008 at 11:12 pm
Hi Terry,
It can be the failure of a backlight. When backlight have problem (after heat up) the display will shutdown after 10 to 30 seconds!Did you test the e-caps with ESR METER?
JESTINE
pecolt
October 16, 2008 at 6:57 pm
Can saw me some In circuit bus BenQ FP-71G+ , what’s the element Q805.Thanк!!!
admin
October 16, 2008 at 10:16 pm
Hi Pecolt,
May i know what is your question? Is it you want to know the part number for Q805? If yes, then sorry i can't get it for you because i have sent the LCD Monitor back to the customer.
jestine
Jatin Khatri
January 9, 2009 at 1:26 pm
hi, I've Banque 17" Q7T4-FP71G LCD monitor. back light was completely dead, so I've replaced the transistors C5707 (which was open ) with the same transistors. now what happens that when I press the power button, screen ( Banque logo) comes for a while and then goes away.. and back light gets off
what do I need to check... can you guide me
ThnX
Jatin Khatri
admin
January 9, 2009 at 9:54 pm
HI Jatin,
Since the transistor was open i guess you need to check the tuning capacitor too as this model are prone to have bad tuning capacitor. Make sure the supply voltage to inverter ic is still there even though the display already shutdown otherwise the main board may have problem.
Jestine
Jatin Khatri
January 10, 2009 at 12:19 am
Thank you Mr.Jestine
problem was the same.. the capacitor was faulty, I've changed it and now LCD is working ok....... Thnx again
Jatin Khatri
Jatin Khatri
January 10, 2009 at 12:26 am
I've one another LCD it is PROVIEW S5A Model No LE1506 , problem is that when I power on the LCD back light gets on but there is no any self raster, if I connect it with the CPU only back light gets on but no picture on the screen, if I disconnect the data cable from CPU, power LCD becomes orange,what could be the problem ????? please guide me.
Thnx
Jatin Khatri
admin
January 10, 2009 at 1:38 pm
Hi Jatin,
If what you meant was white display without character in it then the lcd panel have problem. Make sure the lcd controller board is receiving good voltages.
Jestine
Jatin Khatri
January 10, 2009 at 3:04 pm
I mean to say that no video/picture/self-raster on the screen.. indicator LED functioning properly, Means when I connect the data cable LED becomes green and disconnecting the data cable LCD becomes orange(standby) but no video or picture on the screen
I've tried to get the diagram for the same LCD but it is not available.. if you know any link from where I can download it please provide it to me . BTW I've found this site for the diagram regarding lots of electronics equipments like monitors,TV, DVD/CD players, Motherboards etc... may that can be helpful to others who are asking you to help, you can advice them to search the stuff there ( all the stuff is free.. only free registration is required )
this is the site http://www.eserviceinfo.com/browse.php
admin
January 15, 2009 at 9:16 pm
Hi Jatin,
I guess your case could be a bad lcd panel and thanks for recommending the website.
Have a good day!
Jestine
jatin khatri
January 27, 2009 at 2:09 pm
Hi.. Mr. Jestin Yong
can you provide/suggest any good site for transistor equivalent( I mean to say that the site witch provides the transistor equivalent details etc..)
Thnx in advance
Waseem Aly
January 27, 2009 at 7:59 pm
Thanks for the useful topic
admin
January 27, 2009 at 9:35 pm
Hi Jatin,
Sorry no website on that and usually i will just refer to databook or search from the internet for its specification.
Jestine
jatin khatri
January 28, 2009 at 3:34 pm
ok Thnx
jatin khatri
January 28, 2009 at 3:39 pm
Thnx for your help..
well, I want to purchase your book (hard/soft) from where I can get it, I'm form INDIA, I don't have credit card is there any source in INDIA to buy that books by cash ?
admin
February 1, 2009 at 3:09 pm
HI Jatin,
You can email me at jestinyong(at)electronicrepairguide.com and i will send you my details for western union services to buy my ebook.
Jestine
Shailendra Tyagi
February 11, 2009 at 5:18 pm
I Have a Samsung 19" TFT monitor last 4 year.
Some time before I have a problem in my machine , so I replace by new harddisk with old monitor but now IHave Power on monitor But No Display?
Plzzzzzz help me so that I can repair it.
thanksssss a lot
Shail
India
admin
February 13, 2009 at 10:53 pm
Hi Shail,
Could it be connection problem? If all the connection are good then i guess you have to open the cover and check the inverter ic and make sure there is voltage at the vcc supply pin. Without this voltage then suspect a bad mainboard.
Jestine
kevin heng
February 16, 2009 at 2:57 pm
hi jestine,
i have a LG lcd monitor got white screen when start but got graphic back after a few minutes.it's seems like the contrast over bright.how can i troubleshoot this matter.
admin
February 17, 2009 at 10:15 am
Hi Kevin,
Make sure all the filter cap and the secondary output voltages are good. Check for also any loose connection between the mainboard and the lcd controller board. If all check to be okay then suspect a bad lcd panel.
Jestine
Eric See
February 19, 2009 at 6:54 pm
Please advise , my Benq monitor FP71E has an intermittant interface problem , the contrast adjustment come on & off . button are not responsive including the on/off button most time . Could this be due to a bad joint or cap issue. Will appreciate your feedback. Eric
admin
February 20, 2009 at 9:31 pm
Hi Eric,
Yes it could be dry joints and also bad filter cap and you need to test it with ESR meter. Sometimes a corrupted eeprom data may also cause this kind of symptom too.
Jestine
Butch
March 6, 2009 at 2:26 pm
Q805 and Q812 on my board has 2SC4474 Transistors , not Fu9024 I tried replaceing the (2) 2SC4474 with FU9024 didn't work need help confused about the two 2SC4474 being on the inverter board.
admin
March 6, 2009 at 8:14 pm
Hi Butch,
The 2SC4474 is NPN transistor while the FU9024 IS A P-channel FET. YOU have to get back the replacement which is from NPN transistor type.
Jestine
Butch
March 7, 2009 at 8:05 am
Can you tell me what the function of Q805 and Q812 2SC4474 Transistor does ? The data sheet says a 2sc4474 is a video amp transistor. I don't see how they can be used to fire the lamp's Iam confused. My problem the lamp's don't light. I have replaced the (4) 2sc5707 transistor the fuse and the (2) gray cap's , and resoldered the transformer connection's. I found one of the 2SC4474 open replaced both of them still no go lamps do not light and can not see a image on the screen.
admin
March 9, 2009 at 10:16 pm
Hi Butch,
Since i do not have the schematic so i presume it has the same function of the C5707 that use to switch the high voltage transformer. Has the LCD been repaired by anyone before? May i know what is the model of the LCD that you are repairing?
Jestine
Butch
March 10, 2009 at 1:20 am
Wished I had a schematic that would would help in a big way ! The model # is Q7T4 and it is a Benq. I don't think anyone has tried to repair this. I appreciate you responding to me each time I asked you for help
admin
March 10, 2009 at 10:01 pm
Hi Butch,
You are welcome!
Jestine
Altaf
March 31, 2009 at 5:28 pm
i have crt monitor of 17" view sonic E70 during the openting time shows horizantal lines with whitish shade. can u tell me about this foult i will be thankfull of
thank you
Altaf Hussain
admin
March 31, 2009 at 10:53 pm
Hi Altaf,
Check on the vertical circuit for dry joints, missing supply voltage or even the replacement of vertical driver IC in your CRT Monitor.
Jestine
JETTTT
April 9, 2009 at 4:58 am
Hi Jestine, I have been trying of to check the p-channel fet and i wanna know which is the better way of tester it, according to you experience.
Regards.
Jetttt.
mazhar
April 9, 2009 at 7:35 pm
Can you help me please. I have a 17 inch BenQ monitor model number is Q7C4. I turn on the monitor and computer and it starts to fire up. After about 10-30 sec the screen goes black and the front indicator light is still blue.plz help me
admin
April 9, 2009 at 11:20 pm
Hi Jett,
Normally i use analog meter to test it. For those who have the ATlas peak analyzer they could test the fet very fast and the tester could identify the gate , drain and the source pin. Please visit http://www.peakelec.co.uk/
Jestine
admin
April 11, 2009 at 8:09 am
Hi Mazhar,
This suggest either the backlight or the inverter circuit have problem. Make sure the supply is there in the vcc supply pin of the inverter ic.
Jestine
Ryan Baker
April 15, 2009 at 4:50 am
Hi can you please offer me an opinion on the following problem, I have an HP 1530 that is runnuing a BenQ power supply I have replaced the 470Microfarad caps bnut it still won't run the back light they flick on briefly on startup then go out. Any suggestions on where the problem is would be much appreciated
admin
April 15, 2009 at 11:01 pm
Hi Ryan,
Is all the output voltages stable or fluctuating? If it fluctuating it could be something that had shorted in the secondary side (possibly in the inverter side) or it could be bad component in the primary side. Check also for the ESR of filter capacitors. If it stable then the Mainboard may be at fault.
Jestine
Ryan Baker
April 16, 2009 at 8:35 am
Hi Jestine thanks for your reply I cant test the caps I dont have the equipment but could you tell me what the output voltage should be approximately to the tubes Im getting about 13.5 VAC cheers
admin
April 17, 2009 at 8:58 am
Hi Ryan,
The output to the backlight should have about 500 to 700 Vac. However when the backlight had shutdown the ac voltage would drop to very low or zero volt. Try check the backlight as if one is bad would cause the the display to go off after few seconds.
jestine
Alan Bowring
May 5, 2009 at 6:00 pm
I am looking for some advice. I have a HP1740 LCD Monitor (BenQ) which I got not going - just a white screen - no OSD. Found fuse F1 on the LCD circuit board blown - (5v supply line). The LCD screen model number on the circuit board is M170EG01 V1B. Should I be looking for another faulty part that may be caused the fuse to blow or just replace the fuse? What do I replace it with - what current rating? - what type number? Thanks for your help.
admin
May 5, 2009 at 7:59 pm
HI Alan,
Try a 2 amp fast blow fuse just in case if you could not get the original fuse. Sometime the fuse can blow by itself. I suggest that you test the resistance (using analog meter set to x 1 ohm) between the 5 volt line (after the fuse) to ground and if there is no low resistance you can turn on the monitor.
Jestine
Alan Bowring
May 7, 2009 at 2:00 pm
Further to my query of may 5th regarding BenQ HP 1740 Monitor. I have removed fuse F1 on the display controller panel and have discovered it is a 3 amp rated fuse. I have temporarily wired it to a multimeter to measure current. Current draw is about 4.4 amps and a device not far from F1 gets hot very quick. It is a 6 pin device which I think is Q3 on the board and I see the writing saying D25D and a 17 going cross ways. Can you tell me what this device is and what readings I should expect across it with an analogue meter? I am suspecting it is faulty unless something else supplied though it is causing it to overheat. If I can get a data sheet it would be good. Thanks.
admin
May 10, 2009 at 9:58 pm
Hi Alan,
Since i do not have that lcd with me, i could not test out the part. Sorry no datasheet for that part number.
Jestine
Ruel Zulita
May 27, 2009 at 4:05 pm
thanks you so much for given the replacement parts.
Ernest Leffler
July 9, 2009 at 11:44 am
good day to you,
I hope you can assist me, I have a BenQ Monitor FP71E.
My problem is that the monitor will not go on,
I press the power button and it turns blue for about 2 seconds with no results.
can you assist me.
Thank you for you time,
Ernest
admin
July 9, 2009 at 8:10 pm
HI Ernest,
Is all the output voltages from the SMPS stable?
Jestine
Jose Antonio
July 10, 2009 at 6:20 am
buenas tardes monitor benq q7c4 se apaga despues de que enciende cambie filtro inflado c 712 y trabajo buen tiempo y vuelve al mismo fallo nececito diagrama porfabor el filtro se encuentra bien gracias.
admin
July 10, 2009 at 8:41 pm
Hola,
Lo sentimos, no entiendo su sentido, incluso si ha utilizado el sitio web de traducción de Google. ¿Podría elaborar de nuevo.
Jestine