Philips 50 inch plasma power supply problem

[daw39]

I acquired a Philips 50 PF7321D with a LJ44-00125A power supply problem. Resistors R8006 and R8007 were open. (4.7 ohm high wattage) I replaced them and when powering up they got hot and burned up again. All the caps look good and the ones I can test are good. Anyone had this problem before or does anyone have a schematic for this power supply or where I can get a schematic for this? The board is too crowded for my old eyes to follow the traces. I could easily just order a new power supply but I don't need the TV and just wanted to see if I could remember how to troubleshoot and repair this kind of stuff.

[tom66]

Re: Philips 50 inch plasma power supply problem

Sounds like a shorted MOSFET on the primary side.

[daw39]

Re: Philips 50 inch plasma power supply problem

Thanks for the reply. I had looked at that site and many others for the service manual so far no luck. The ones I have found don't have the power supply schematic??? I have pulled a few components, high current bridge, caps in the area and tested those, with the large coils and transformers taking up so much real estate hard to follow the traces. If anyone has the schematic for the above listed power supply I would be appreciate it.

[tom66]

Re: Philips 50 inch plasma power supply problem

LJ44-00125A sounds like a Sammy PSU. Let me check...

[daw39]

Re: Philips 50 inch plasma power supply problem

Samsung yes, 20060705 rev2
PS-505-PHN LJ44-00125A
Don't know if any of the other silk screen marks help?
Thanks

[crashp3]

Re: Philips 50 inch plasma power supply problem

Just took a look.. I don't have access to Magnavox or Philips service site, and according to ShopJimmy this Samsung power supply was never used... in a Samsung, which I have access to

[daw39]

Re: Philips 50 inch plasma power supply problem

Thanks for looking, I may just end up wearing a solder sucker out following the traces....
Was poking around and read around 8 ohms across the NO contacts of a relay???RLY8001 removed it relay was good,, contact pads read about 8 ohms??? I know i could beat this if I had a drawing.... then again if i give up I'll put a wire across the resistors and follow the burned trace. I'll figure this out one way or another. LOL.

[jhd2112]

Re: Philips 50 inch plasma power supply problem

Search Tom66 on forum because he has a list of where to get service manuals for your TVs. I read all of his advice because he a true Blue Veteran on plasma repair. scince he read your post, so he might send you the link. Randtek on the forum opening page has a link to tom66 Plasma tv library, because that is where I got mine,and it is free. I allways chose to donate money to pay for the vast supply of manual on line. Good luck

[Alastair E]

Re: Philips 50 inch plasma power supply problem

Check the MOSFETS on the big heatsinks--No need to follow traces, just check 'em all....