Philips 47PFL7642D/12

[thejay]

I've turned on a Philips 47PFL7642D/12 LCD TV after about a year.
Screen stays black, no backlight, no sound. Power-on-LED turns blue as expected.
I already replaced the four caps on the two inverter boards as they looked vented. The only fuse I found is on the power supply board and is ok.
Where to begin?

[budm]

Re: Philips 47PFL7642D/12

Are you getting 24VDC on both ends of that white fuse (chassis as GND ref for the meter) on the inverter boards? Do you also see if the backligts even flash on for seconds?

[selldoor]

Re: Philips 47PFL7642D/12

Give it a good dusting - brush and vacuum should do it.
Was it working before it went into storage

[thejay]

Re: Philips 47PFL7642D/12

Thanks for all replies so far!

@budm: Forgot my meter at work, can't do it before tomorrow.

@selldoor: Yes, it worked before. But I guess it was already dusty back then :-)
(I'll clean it nevertheless and give it a try)

@all: Nobody noticed the cap I've resoldered with reversed polarity yet? Unfortunately it wasn't the cause either.

[selldoor]

Re: Philips 47PFL7642D/12

If you switched it on with the cap reversed you should consider changing it again.

[thejay]

Re: Philips 47PFL7642D/12

Don't worry, I used a new one

[thejay]

Re: Philips 47PFL7642D/12

@budm: I get a 0V reading on both ends of both fuses. Backlight stays completely off.
So I guess the problem is rather on the power supply side?

[selldoor]

Re: Philips 47PFL7642D/12

Maybe , maybe not. try unplugging replugging all the connectors a few times to clean off any oxidation then with it all plugged in and connected up test all the pins on all the connectors post results like
CN?
pin 1....12v....11.99v
pin 2.... 5v.....2.48v and so on

on connector cn 7 there is a pin PSON can you use meter on vdc20 and monitor what happens on that pin from plug in to switch on to fault position.

[truep]

Re: Philips 47PFL7642D/12

Also check the caps under the power supply heat sinks. The engineer(?) that designed that should be fired!

[thejay]

Re: Philips 47PFL7642D/12

Heureka! Found one obviously vented cap right below the large heatsink. Replaced it and everything works fine now.
Final question: Does it make sense to replace the remaining three old caps as a precautionary measure? I ask because this will be rather complex. They really managed to solder the heatsink to the board!