Benq FP91G+

[ugurpasa]

Dear all,

I have a Benq FP91G+ that powers on, green led on the power button comes up for a second and dies. There is nothing on the screen during this. I have opened the case and the power supply PCB seems to be significantly discolored at places. I have read about transistors in these boards to go bad. I have not taken any measurements yet, but I am looking for pointers on the where to start.

Here is a couple pictures from the board. If asked I'll upload close-up pictures as well.

Thanks in advance,

-UP

[jetadm123]

Re: Benq FP91G+

Welcome to the forum! Nice photos always help.

You could potentially several problems:

1) About half your caps appear to be bulged, which is a key indication they are bad. They should ALL be replaced with low-esr caps with the exception of the large 450V (unless it's also buldged or leaking).

2) Failures of these boards are also caused by poor solder joints on the 4 inverter transformers. Resolder all the legs of each inverter transformer.

3) The poor transformer solder joints can cause the following to fail:
Q806,809,815,816 (2SC5707?)
Q805,812 (FU9024N?)
PF801 fuse

Check the transistors for shorts and the fuse for continutity. If they check good, then your problem "MIGHT" be just the caps.