philips 47PFL8404H random black screen

[london-freddie]

Just got this Philips 47PFL8404H very cheap £20 with half dim screen
found little blue 6Kv smoothing cap burnt, on inverter/power board replaced it and screen came back full brightness
Great result yes, But, now the problem
After tv has been on for some time it randomly black screens, sound is still there and everything seems to work except no picture.
Switch tv off at mains let it cool down for a while and power set up again and it works again till it black screens again randomly.
I think this is overheating somewhere, it seems to be very hot, and cooling the set down with a fan through the vents seems to bring the picture back quicker
power board DPS-298CP-2 will post a picture of the power board next time I have the back off the set

[london-freddie]

Re: philips 47PFL8404H random black screen

Forgot to mention all caps physically look ok with no bulging or leakage, but will change them when I get some replacements

[CapLeaker]

Re: philips 47PFL8404H random black screen

as usual we are going to need good high res pictures of the boards and the pin outs.

[london-freddie]

Re: philips 47PFL8404H random black screen

Not my power board but is the same as mine, blue cap that I replaced is top left

[CapLeaker]

Re: philips 47PFL8404H random black screen

we want yours! there are other signs too besides bulging and leaking.

[london-freddie]

Re: philips 47PFL8404H random black screen

ok will do however will be on Monday as am working away and not at home

[tom66]

Re: philips 47PFL8404H random black screen

Make sure to check the power supply voltages.
If you suspect the PSU to be faulty, there should be a sign, such as the 5V rail dropping out.
I would focus on main board / T-con / panel
See if it overheats quicker if HDMI is used vs Freeview for example
Also if it has 100Hz motion interpolation try turning that on/off

[london-freddie]

Re: philips 47PFL8404H random black screen

will check Monday when home. will run tv with back cover removed when it black screens I can check power supply voltages quicker
At the top centre of the power board there appears to be a pot for adjusting a voltage to something any ideas what
been searching the net for a while this seems to be a quite common problem/fault on these power boards no fix that I have found but most seem to steer towards caaps and solder joints, I did look for dodgy solder joints when I had the board out all looked ok, may have to have a closer look