Samsung Plasma PN50B450B1D Dim picture, black pixels

[tom66]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

You have to match the PBA number, shopjimmy has some videos on Samsung part numbers.

[Glitcher]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

PBA numbers were exactly the same. The only difference I noticed was the big circled number 1 on the board. The new one I bought had a number 2 but all the PBA PCB and REV numbers matched.

[tom66]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

Check suffix code too, e.g. A/B/C/D/E/F. 42" board in 50" will also not work.

[Glitcher]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

Yeah there were no marks on the suffixes, the codes were exactly the same

[Glitcher]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

Well just got another control board, put it in but symptoms are the same as the beginning.

Just bought a new multimeter also, since the old one finally gave out on me.

I re-measured all of the voltages. I now find that Ve is kind of at a steady 87.5V (Spec says 88V) So I think I can rule out the X-main now and the control board out.

Vs measures 210V, Va measures 55V (both same as sticker specs) The only think that's does not give a correct reading is the Vscan.

VSCAN is fluctuating everywhere (no where near spec). Unless I isolate the y-main then Vscan will read on spec at -193V. So the problem is the y-main im guessing.
I already checked every FET and diode on the heatsink and they all checked good though.

[Glitcher]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

more photos of problem

Ugh I'm just annoyed to hell with the luck ive been having. I just bought two PSUs, two X-mains, a Y-main, and a main board for this set. If that doesn't fix it nothing will.

[Glitcher]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

Problem is finally solved!

Turned out to be a bad PSU. (Would of never even guessed...) After swapping everything else first (X-main, ctrl, main board) I tried the new PSU and it finally fixed the problem. I had a great deal on all the extra parts that ill probably resell for some profit.

In the mean time I'll see whats wrong with the old psu. I would be so pissed if it actually turned out to be bad caps or something simple like that..

[tom66]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

Huh. I am surprised. The only thing that could possibly cause this would be very, very low Vs from the PSU (say around 130 to 150V instead of typical 205-210V.) Is that what you had?

[Glitcher]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

The Vs was measured at a steady 210V. The only voltage that was strange was the Vscan.

[tom66]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

I cannot see how a power board fault caused that then. Is it plausible that you have a cold joint on the X-main that has temporarily repaired itself after seating the cables again?

[Glitcher]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

I replaced another two new x-main boards first but it still had the same problem and I reseated it a good amount of times when I was testing it. Strange hmm

[tom66]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

I'd watch it very carefully for at least a week before selling/keeping/returning-to-customer.

[Glitcher]

Re: Samsung Plasma PN50B450B1D Dim picture, black pixels

The Tv has been running perfect for aboue an hour now. I decided to switch to the old PSU to reconfirm and after putting the old PSU back in, the original problem returns, so this is indeed a PSU fault.

Heres some photos of the X-main and Y-main when the TV is in working condition.