Problem with BenQ FP731 17" LCD monitor

[Newbie2]

Hello people,

One of my 3-year-old BenQ FP731 17" LCD monitors failed. When I power it on, it will display a very faint BenQ logo (no backlight so it was black), and then the whole screen goes pitch black as if it was off.

I've been reading things on the Internet and it may be with the inverter board, etc.

I do not have disassembly pictures as I did not disassemble it yet, but can anybody guess what the problem is?

Any suggestions appreciated.

EDIT: The green power LED was on while the monitor was plugged into a powered-on computer, but nothing can be seen at all on the monitor. Shining a bright flashlight did not reveal anything, so the whole display must of been off.

[Krankshaft]

Re: Problem with BenQ FP731 17" LCD monitor

Most likely a shorted inverter transistor and fuse or bad capacitors on the board.

[Newbie2]

Re: Problem with BenQ FP731 17" LCD monitor

I myself and my buddy who's an electrical enginner have found out that two of the 2SC5707 transistors on the board have failed along with a 3A fuse at the PF751 location on the board.

I couldn't find the exact SANYO 2SC5707 part at Digikey, so I ordered a few D44H11 transistors. I checked the specs and my buddy says it's a suitable replacement.

Is the D44H11 transistor (spec sheet: ) a suitable replacement for the 2SC5707 (spec sheet: )?

[Krankshaft]

Re: Problem with BenQ FP731 17" LCD monitor

You will have some problems reinstalling the case with those larger parts and may need to dremel the metal casing.

This is due to the larger TO-220 packages of your replacement parts.

Another substitute that has worked is the MJE3055.

The proper 5707s are available on e-bay.

http://search.ebay.com/search/search...707&category0=

They are pretty cheap and will install without any modification.

As for the pico fuse Digikey does have that.

[Newbie2]

Re: Problem with BenQ FP731 17" LCD monitor

I already placed an order on Digikey for a few D44H11 transistors, I'm asking will they work as a substitute for the 2SC5707?

I already mentioned the MJE3055, and after he looked at its spec sheet he said they could work but if they did work they would be very hot.

[Krankshaft]

Re: Problem with BenQ FP731 17" LCD monitor

Aside from the increased size and the need to either bend them over or cut out the rear metal panel to make them fit.

Specs wise they will work just fine.