Phillips 50PF7521d/12 Wont turn on

[Johnboy78]

ive just got this tv, and when plugged in the green light came up and i could hear relays clicking a few times but not much else, no pic or sound. I can press the power button then the green light goes out which i guess means its on? Ive taken it apart and replaced 2 caps that were domed....but also on the board there is 2 large 130c 63v caps which are gold in colour and these are really bulged so need replacing, does anyone think it could be those 2 causing the problem? im struggling to find them anywhere for sale.

Is it also worth trying to unplug the audio board which i read in another post about this tv and did the trick? any help would be good. thanks

[tom66]

Re: Phillips 50PF7521d/12 Wont turn on

Can we see some pictures?
Audio board -- may as well try -- can't see the test taking longer than 5 minutes...

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

Where would i find the audio board? ill try and get some pics tomorrow as ive put the tv back together now.

What test do u mean? i dont know alot about tv's to be honest.

[Alastair E]

Re: Phillips 50PF7521d/12 Wont turn on

C2508 in PSU.

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

whats that alastair?

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

The tv has all samsung internals by the way.

[tom66]

Re: Phillips 50PF7521d/12 Wont turn on

2508 is a capacitor on the PSUs used in models like this that tends to fail, but I'm not sure it's applicable to Samsung-based panels.

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

ok thanks ill have a look at that later. What photos do u need and ill see if i can get them.

[tom66]

Re: Phillips 50PF7521d/12 Wont turn on

It's on the power supply board, this is the board that the AC power comes in to.

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

also thought i would mention underneath the 2 gold caps it looks like it got pretty hot as there is brown marks around the solder joint slightly, not sure if it makes a difference.

[tom66]

Re: Phillips 50PF7521d/12 Wont turn on

Probably just solder flux -- those are too big for wave solder so may have been hand soldered.

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

i see. So ive taken a few pics hopefully you can give me some things to try?





if you need any others let me know.

you can see the 2 gold caps that are bulged....and the 2 brown/grey caps bottom left are the ones ive replaced.

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

PSU number LJ44-00108C

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

quick update....i found the audio amp card, unplugged and powered it on and it now switches on no problem, so im making progress just need to find a replacement card now.

[capkid]

Re: Phillips 50PF7521d/12 Wont turn on

The audio amp board can be repaired, but it's a delicate procedure, since it's a single-sided board whose component rings are easily lifted if too much heat is applied. I found that a couple resistors were bad. The boards are usually about $10 - $15 on eBay. It's hard to tell from your pic, but it looks like some caps are bulging on the audio board.

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

yeah its ok ive just found one on ebay for £7 rather then messing with the old one. My next question is, will the tv still have sound even if that amp board is disconnected? or would it work through a surround sound system?

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

The board in question is in the first pic, very top right corner. Its a philips board with the 2 ribbons going to it, 1 is supply (from the psu) the other is audio

[capkid]

Re: Phillips 50PF7521d/12 Wont turn on

I spent numerous hours testing the PSU, and I even replaced the PSU. After the replacement didn't resolve the issue, I then started disconnecting PSU loads to see if I could get the PSU voltages to come up. That's when I isolated the problem to the audio amp board. What a pain! It was a good learning experience, though.

[Johnboy78]

Re: Phillips 50PF7521d/12 Wont turn on

did you test your audio with the card removed? sorry if thats a silly question lol

[tom66]

Re: Phillips 50PF7521d/12 Wont turn on

Definitely replace those caps on the PSU, even if the audio board removal fixes it, because sooner or later the TV won't work at all. Those capacitors can be replaced with Panasonic FC, FM or FR available from Digikey. -Do not- use capacitors from retail shops like RadioShack as they are not suitable for TV power supply.