Fix for Benq FP737s 17" (Q7T3)

[Lim Yong Seng]

Re: Fix for Benq FP737s 17" (Q7T3)

Hi Everybody,

Thanks all of you for the useful postings which help me to repair a BenQ FP731.
It does not have any display with the green LED stays on.

Things done
-------------
1. Replaced fuse (BEL MS 3A), PF751 is open-circuit. I used a 2A pico fuse because I do not have a 3A fuse on hand.

2. Solder inverter transistors (2SC5707), Q739, Q740, Q759 and Q760. The solder cracked when I moved these 4 transistors.

3. Solder power MOSFETs (FU9024N), Q743 and Q751. The solder cracked when I moved these 2 MOSFETs.

4. Solder transformers, T751, T752, T753 and T754. No solder cracked, just re-solder to prevent dry joints.

5. After power on, left half of the monitor displays information correctly but right half has pink background with a continuous black line in the centre of the screen.

6. Remove the two flex-cables and clean the contacts (dirt found) with alcohol.

7. Power on and the monitor is in working condition.

Once again, thanks all you for the important information.

Have a nice weekend...Yong Seng

[vicrowley]

Re: Fix for Benq FP737s 17" (Q7T3)

Thanks for the advice, and as far as the actual work of the board is concerned, I'm fairly confident on that score. In the past when I used to work for my living (now retired), I was for a few years in a data collection lab, and soldering strain gauges, some of which were only thirty thou long, and that included the two solder tags. So we had to work under a 30 to 1 microscope. I guess that's why I now need glasses. So like say the physical stuff I can deal with, it's the technical working of these modern electronics I know nothing about. It's all black boxes (Chips), and unless I know what each of these does and how it achieves it, I'm lost. So thanks for doing all the hard work, and I'll let you know once I've completed the task, if my confidence was well founded or not.

Vic

[davmax]

Re: Fix for Benq FP737s 17" (Q7T3)

I feel I should add that to achieve the modification I describe you will need all the tools.
A soldering iron and self fluxing solder.
A PCB drill and bit 0.8 - 1 mm
A sharp knife to cut tracks.

[davmax]

Re: Fix for Benq FP737s 17" (Q7T3)

In response to a request for the final modification details
I have made this easy by posting the final versions at an online album here: http://picasaweb.google.com.au/davmax60/MonitorRepairs#

Use the full screen facility to see the detail.

Please note that there are two versions of current sense resistor, either a single resistor or two in parallel. Therefore the photo of the board underside shows the 0.082 ohm resistor version (alternately this resistor would be 0.56 ohm). The photo of the upper board shows the position of the 0.1 ohm resistor.

[vicrowley]

Re: Fix for Benq FP737s 17" (Q7T3)

Thanks, will look and see how to do that.

Vic

[EGuevarae]

Re: Fix for Benq FP737s 17" (Q7T3)

Hi Dave,
I have recently been given one of these Benq 17” monitors, but only because it had died. I'm only an amateur dabbler in electronics, and I think I've just about been able to follow most of your circuit mods, and the reasoning behind them. Now I know from the dates on the posted articles, it was some time ago you were working on this monitor, but I was wondering if you now have a final definitive modification list, and final circuit diagrams. I ask this as reading through the various posts, you were obviously developing and changing things as you found new problems, and from reading through, it is hard to be sure I'm using your final solution for all the mods.

PS. I hope I've entered this in the right place, I'm new to this forum.

Vic

Welcome to the forums.
While the post is in the right place, you might want to PM davmax directly.

[vicrowley]

Re: Fix for Benq FP737s 17" (Q7T3)

Hi Dave,
I have recently been given one of these Benq 17” monitors, but only because it had died. I'm only an amateur dabbler in electronics, and I think I've just about been able to follow most of your circuit mods, and the reasoning behind them. Now I know from the dates on the posted articles, it was some time ago you were working on this monitor, but I was wondering if you now have a final definitive modification list, and final circuit diagrams. I ask this as reading through the various posts, you were obviously developing and changing things as you found new problems, and from reading through, it is hard to be sure I'm using your final solution for all the mods.

PS. I hope I've entered this in the right place, I'm new to this forum.

Vic

[EGuevarae]

Re: Fix for Benq FP737s 17" (Q7T3)

Very sharp, cant stop laughing, nice one

Yes. It is ironic indeed, a FU FU component...
"You must replace the FU."
"Which one?"
"The one that is FU..."

[Bobdee]

Re: Fix for Benq FP737s 17" (Q7T3)

Hehe FU how ironic.

Think the component is telling you something ?

Very sharp, cant stop laughing, nice one

[Krankshaft]

Re: Fix for Benq FP737s 17" (Q7T3)

Hehe FU how ironic.

Think the component is telling you something ?

[EGuevarae]

Re: Fix for Benq FP737s 17" (Q7T3)

while i been waiting your answer ..i try by my multimeter tester to measure and i found the fq11p06 short..so in this condition the backlights is always on , also the power button is off
i think to have the same problen in both monitor
well i hope to solved this problem ..and thank you very much for your help

The shorted FU is the cause for your always-on backlight. The one with the white only display is another story, as it will be the input fuse almost for sure as Bobdee said. if the Fuse is OK, then you will have a bad LCD panel.

[diabolik_0ne]

Re: Fix for Benq FP737s 17" (Q7T3)

while i been waiting your answer ..i try by my multimeter tester to measure and i found the fq11p06 short..so in this condition the backlights is always on , also the power button is off
i think to have the same problen in both monitor
well i hope to solved this problem ..and thank you very much for your help

[Bobdee]

Re: Fix for Benq FP737s 17" (Q7T3)

now i repeir a benq model t905 i change two 5707 and the fuse 3 amp ....the Backlights now are ok and visualizze image ....but when i turn off to the power button....the Backlights still light on ....why?? if i turn off the monitor i cut the corrunt cable ...some help me please.

Check the 2 fets out for shorts (FU9024Ns) they look the same as the C5707s and they will be near to them

read this by Krankshaft it will help
https://www.badcaps.net/forum/showpo...&postcount=240

[diabolik_0ne]

Re: Fix for Benq FP737s 17" (Q7T3)

now i repeir a benq model t905 i change two 5707 and the fuse 3 amp ....the Backlights now are ok and visualizze image ....but when i turn off to the power button....the Backlights still light on ....why?? if i turn off the monitor i cut the corrunt cable ...some help me please.

[Bobdee]

Re: Fix for Benq FP737s 17" (Q7T3)

the lamp are light on... and the screen i see only white color if i connect the vga cable the screen to the pc i don't see any image i see only white colour

yes I do understand that, those are the symptoms of the PANEL fuse dying so check panel fuse first to see if that is your problem, If the panel fuse is OK then the problem will be mainboard, but I and a few members have repaired this problem on various monitors just by replacing the usual 1 amp fuse on the panel (not the power or mainboard the Panel board)

[diabolik_0ne]

Re: Fix for Benq FP737s 17" (Q7T3)

the lamp are light on... and the screen i see only white color if i connect the vga cable the screen to the pc i don't see any image i see only white colour

[Bobdee]

Re: Fix for Benq FP737s 17" (Q7T3)

sorry for my last information it' no complete.....
i,ve just change the pico-fuse on mainb 3 amp. the lamp swicht on ,the screen only white colours....nothin image visualizze , i need to change other components??

Not sure that I understand that last post,
but when the panel fuse is open the Backlights (lamps as you call them) do come on to give you white screen but no visual image,

So a dead panel fuse leaves you with white screen (lamps on) no image

[diabolik_0ne]

Re: Fix for Benq FP737s 17" (Q7T3)

sorry for my last information it' no complete.....
i,ve just change the pico-fuse on mainb 3 amp. the lamp swicht on ,the screen only white colours....nothin image visualizze , i need to change other components??

[Bobdee]

Re: Fix for Benq FP737s 17" (Q7T3)

hi, i have a benq monitor lcd fp737 , i've just change the some capacitor and the fuse,
now it swicth on but the screen is white, no image visualizze
i need help please

First check your lead from mainboard to panel ,this can be easily unseated or left off in some cases when monitors have been opened.
Also if that not problem check tiny fuse on panel (not much bigger than pinhead in most cases) that is under metal plate at top of screen

[diabolik_0ne]

Re: Fix for Benq FP737s 17" (Q7T3)

hi, i have a benq monitor lcd fp737 , i've just change the some capacitor and the fuse,
now it swicth on but the screen is white, no image visualizze
i need help please