BENQ FP91G+ no longer working - Help!!!

[chockimon]

I have a BENQ FP91G+ 19" LCD that is no longer working. The power LED flashes and goes off and I get no picture whatsoever, not even the logo. Does anyone know what the problem might be and how can I fix it.?



I took the monitor apart and noticed at least 5 bulging caps (Marked in Red) and where I have circled in red there is a burn mark.

How much does it cost (£) to buy replacement components and where online can I buy them in the UK. Out of curiosity does anyone know how much a new inverter board would cost? I'm no expert in electronics, so what do I need exactly to repair this monitor. I'm ok with a soldering iron though.

Thanks! I appreciate any help you can offer.

[gerg]

Re: BENQ FP91G+ no longer working - Help!!!

what is the rating on the caps that are bad?

[cpp]

Re: BENQ FP91G+ no longer working - Help!!!

replace all caps on the secondary side and the big one-(100uf 400v?, line filter, on the primary) and try power on again.Sometimes , Benq boards are easy to repair.At the moment ,no need to replace the two 47 uf 50v near the power mos-fet

the circled in red is a "optocoupler" ,normally Benq mount types 817 or pc123,if are burned ,change it,it 's cost inexpensive

Look this:
http://foros.zackyfiles.com/showthread.php?p=4111852

(sorry for my english)

[PlainBill]

Re: BENQ FP91G+ no longer working - Help!!!

There are several members here from Britain. RS and Farnell are two of the suppliers I hear mentioned.

One correction to earlier advice. Benq has a reputation for using low quality components. Unless you enjoy pulling the monitor apart, replace all of the electrolytic capacitors on the board. Ordinarily I say "with the possible exception of the large 100uF, 450 volt one", but the symptoms you describe could be caused by a (rare) failure of that capacitor. In particular, the two 47uF, 50V ones should be replaced. They are inexpensive, and if they fail you will have a non-working power supply.

Personally, I prefer Panasonic FM or FC series caps. Other brands also have series that are good replacements.

Note the links in my signature. They lead to information on suitable capacitors, sources for them, and also tips on attaching pictures to your post.

PlainBill

[chockimon]

Re: BENQ FP91G+ no longer working - Help!!!

HI gerg, my monitor is in the loft at the moment, so I couldn't tell you, but I'll have a look at the weekend. I've had to send my new Acer GD245HQ monitor back due to vertical banding, so I'm going to be without a monitor for a while, so I might as well try and fix my Benq.

[chockimon]

Re: BENQ FP91G+ no longer working - Help!!!

HI CPP & PlainBill. Thanks for the information. I'll see if I can buy the components you mentioned at the weekend. Thanks for the really good links. They'll no doubt be very helpful. Thanks again. I'll let you know how I get on. Hopefully I should be able to fix it now.

[retiredcaps]

Re: BENQ FP91G+ no longer working - Help!!!

I'll see if I can buy the components you mentioned at the weekend.

You *must* resolder all the inverter transformer pins. Benq boards have weak or poor solder joints on the inverter transformer pins.

They are also known to have possibly bad picofuses, c5707s, and fu9024s.

[wanyf]

Re: BENQ FP91G+ no longer working - Help!!!

I have the same issues, after reading badcaps forum, i replaced all secondary caps, four C5707, two FU9024N, and a 3A 125V pico fuse and it works.
After 2 days of running, covered about 24hrs, it goes off again.
I wonder i miss out some components? please help.

[PlainBill]

Re: BENQ FP91G+ no longer working - Help!!!

I have the same issues, after reading badcaps forum, i replaced all secondary caps, four C5707, two FU9024N, and a 3A 125V pico fuse and it works.
After 2 days of running, covered about 24hrs, it goes off again.
I wonder i miss out some components? please help.

Read post #7. Did you do resolder the transformers?

PlainBill

[chockimon]

Re: BENQ FP91G+ no longer working - Help!!!

Well I've resoldered all the inverter transformer pins like you said and it's still not working. So it's definitely probably something else. The following caps are bulging, so probably need new ones.

C712 608C2 (TK)P105, 1000uF/10V
C707, C708 (C)0551 ELM 105c,1000Uf/16V
C704 (C)547,470uF/35V

Being a layman, all these numbers are confusing. I'll need to order the same capcitors from somewhere. Any idea how much 4 or 5 capacitors will cost?

What's the pico fuse?

On mine there is what looks like a fuse beside the power socket, could this be blown?

[seanc]

Re: BENQ FP91G+ no longer working - Help!!!

So you need:
1 x 1000uf 10v capacitor
2 x 1000uf 16v capacitors
1 x 470uf 35v capacitor

You'd be wise to change out all of the capacitors, if some have failed, the rest will.

I'd recommend Panasonic FM capacitors, you can get them from RS Components - their shipping prices are the most reasonable I've found.

The pico fuse is a small axial fuse that looks a bit like a diode. It will be marked PFXXX.
Check it for continuity, it should read 0.3 ohms.

[retiredcaps]

Re: BENQ FP91G+ no longer working - Help!!!

Well I've resoldered all the inverter transformer pins like you said and it's still not working. So it's definitely probably something else. The following caps are bulging, so probably need new ones.

C712 608C2 (TK)P105, 1000uF/10V
C707, C708 (C)0551 ELM 105c,1000Uf/16V
C704 (C)547,470uF/35V

You need to resolder all the inverter transformer pins *in addition* to replacing the capacitors. If your caps are bulging, there is NO WAY the LCD will work.

Benq boards sometimes have multiple failures on the same board. It can have bad caps, open picofuse, bad soldering, and shorted transistors.

Being a layman, all these numbers are confusing. I'll need to order the same capcitors from somewhere. Any idea how much 4 or 5 capacitors will cost?

If you are in the USA, you can buy the caps here at badcaps.net or follow PlainBill's instructions at

https://www.badcaps.net/forum/showpo...33&postcount=2

What's the pico fuse?

On the board, it is marked PFxy. Your pic is too blurry to tell, I'm guessing it is in the top right hand corner just left of the heat sink.

A good fuse measures less than 1.0 ohms on your multimeter.

[Steveo41]

Re: BENQ FP91G+ no longer working - Help!!!

Just joined to say thankyou. One of my 3 FP91G+ had this exact fault and because its part of a 3 screen wide setup I was feeling pretty gutted because I need matching screens.

Thanks to you guys and a few new capacitors later, its back up and running. I can't thank you enough for providing such valuable information.

Best wishes
Steve