Benq fp73g s strange behaviour

[conan981]

Hi to all
First of all thank you for all the infos, suggestions and hits that all the members of this forum give to newbies like me.
I want to ask your help for my BENQ FP73G S 17" monitor.
Monitor is not working correctly.
If i put it ON without be attached to a video source, the monitor starts all white, then start to become violet then black from the center of the screen, then after some seconds goes in standby as it should.
When it is attached to a video source, monitor have 2 sec of black, then it works correctly all the time...
I am sorry for my poor english, and i know that may be i was not clear so here in attachments there are some photos of this behaviour.
ps. i made a try replacing 4 x 330uF 35V caps and resoldering inverters.
ONLy the first time monitor show me the benq logo as it should, then all the other times it did the same as described before.
I hope someone have an idea and can help me
Thank you again
conan

[senndogg]

Re: Benq fp73g s strange behaviour

can you post clear photos of the main board? is OSD shown correctly?

[conan981]

Re: Benq fp73g s strange behaviour

Sorry, At the moment i cannot do clear photos i'll make me lend another photocamera.
Btw, OSD is not displaying correctly if no video source is attached.
If video source is attached after 2 sec all is working ok.

[selldoor]

Re: Benq fp73g s strange behaviour

Hi - First can you update your profile with country and mains voltage.
Pics are not too bad I have seen a lot worse. - Monitors do many different things when no source is connected. Some dells flash a series of colours.
Perhaps you can repost the pic after marking which caps you replaced.
I see Multicomp capacitors on there these are not usually recommended for power supplies. What did the monitor do before you replaced the caps.
If some caps had burst/ bulged/ dried out it is likely that all the caps for that make and series will be ready for replacement.

Can we have pictures of the other board - top and bottom

EDIT
If Poor caps have not already damaged other components a recap with GOOD capacitors could get it running again

[conan981]

Re: Benq fp73g s strange behaviour

profile updated, sorry
This benq, if would be working, should show for a few second the BENQ logo in a rectangle.
The monitor before replacing these caps did always the same defect i described in post 1. I tested even all the caps replaced with capacitor and all seem to be fine. In attachment the photo with the caps i replaced and their specs.
all of them are branded JAMICON (i don't know if it is good) but are 105°C
I want to say that after replacing the two capacitors near the inverters, the first time i put ON the monitor, all seems to go fine, but when tried again, the defect was there again..
now my camera is chargin, I'll do the logic board photos as soon as i can
Thank you

[conan981]

Re: Benq fp73g s strange behaviour

here are the photos of logic board.
anyone have an idea?

[selldoor]

Re: Benq fp73g s strange behaviour

OK Can we just go through the problem again.

I dont think we need worry about when there is no source?
Why would you want it on with no source?

Computer up and running and shows desktop.

You put the vga lead into this monitor and switch the monitor on

It stays black for 2 seconds then comes on and then works as normal.

Is that correct?

If you switch it off then back on does it come on at once. (warm caps sometimes work better as the ESR may become lower)

When you say you tested the caps was that with an ESR Meter?

With it all connected up can you check the voltages out (at the connector near the 1000uF 10v caps on the power supply board and post them.

If possible try and do it in the 2 sec while the screen is black and again when it is on.

I still think you should start by re capping the whole board the green caps are Lelon brand which are not good for this application. It sounds as though it is taking time for the caps to charge up to a working voltage.

[tom66]

Re: Benq fp73g s strange behaviour

This weird pattern is caused if power to the T-con is insufficient or turns off while the backlight is still on.