HP-T5054 Samsung Plasma Screen Issues

[dustman1747]

I have acquired a Samsung HP-T5054 plasma tv that I have been working to repair with the help of information ive found in these forums. However it seems I have fixed one problem and ran into another that I cannot seem to find an answer to.

The problem started as a black screen and then a pop according to the previous owner.

Symptoms:
power cycling constantly
no image

Findings
Tv powered on with y-sus unplugged
Upper Y-buffer had an obvious bad IC

Fix:
Replaced both Y buffers
Replaced 88N30W (Q5302,Q5303,Q5305,Q5306), RJH3047 (Q5100-Q5103), K2837(Q5200, Q5500) and B20NK50Z (Q5501)

Results:
Tv powers on with image but image is distorted, hence the current problem

Current Problem:
Tv powers on but the image is faded on the right side of the tv, the left side of the tv has vertical lines evenly spaced. Every once in a while the screen goes pink and the power supply whines as if there is a problem. I tried another X-sus in the tv but the problem still reoccurs. The tv also shows a weird pattern when shutting down or turning on.

Voltages appear to be within spec.


Pictures in the next post. Any ideas?

[Ltank]

Re: HP-T5054 Samsung Plasma Screen Issues

With the Y Board power disconnected will the P.S. still cycle on/off? If it stays on the you still have a problem on the Y board. Try the X board too to determine the cause. What if both are disconnected?

[dustman1747]

Re: HP-T5054 Samsung Plasma Screen Issues

1) With X-sus plugged in

2) Shutting down:

3) Without X-sus

4) Right side is darker

5) Vertical lines shown on test pattern

6-7) Weird colors and distortion on test pattern

8) Pink distortion the sometimes shows with X-sustain plugged in

[dustman1747]

Re: HP-T5054 Samsung Plasma Screen Issues

With X-sus disconnected panel displays no signal indication and static.

With Y-sus disconnected the tv the relay clicks and the tv try to power on about every 10secs, no image

With both disconnected the tv appears to power on and stay on, no image

[freakaftr8]

Re: HP-T5054 Samsung Plasma Screen Issues

your having the exact same problem I am having with the exact same model. Even though you replaced all the bad MOSFET transistor is on the Y sustain board there is still something wrong I replaced my whole Y board and problem solved

normally I never give up on repairing a board but however I had to on this one it was getting too pricey. Even though the MOSFETs tested good apparently they're still bad

[freakaftr8]

Re: HP-T5054 Samsung Plasma Screen Issues

the reason the power supply wines or buzzes is because it's pulling more amperage that it's allowed to due to a still apparent fault on the y sustain board

[dustman1747]

Re: HP-T5054 Samsung Plasma Screen Issues

The buzzing or whining seems to come and go. It is usually only present when the the screen goes pink and seems to go away if I play with the X-sus ribbon cables.

That screen distortion can be caused by the Y-sus even though the lines are all vertical?

I'm already in deep on this one. Any ideas what other mosfets it could be?

[mmartell]

Re: HP-T5054 Samsung Plasma Screen Issues

Control boards are cheap for this set, may account for the vertical lines. Have you checked over your xsus carefully ?

And make sure you haven't damaged any of the mosfet via's on removal like I did because those mosfets are soldered at the top and bottom of the board.

[freakaftr8]

Re: HP-T5054 Samsung Plasma Screen Issues

yes that screen distortion is caused by the Y sustain. I've tried changing out control boards on mine with the same result. Somehow the why its not sending the control board the proper information so the control board is distorting the left hand side of the screen even though the right hand side is still messed up its a different distortion.

you mentioned in your first post that you swapped out all bad MOSFETs. But you did not swap out the two K2837's? I found those causes distortion problem as they are not powering the other bank of MOSFETS properly. these act as a controller

[dustman1747]

Re: HP-T5054 Samsung Plasma Screen Issues

you mentioned in your first post that you swapped out all bad MOSFETs. But you did not swap out the two K2837's? I found those causes distortion problem as they are not powering the other bank of MOSFETS properly. these act as a controller

I swapped out both banks under the heatsink nearest the buffer including the 88N30W, RJH3047, K2837 and one of the smd transistors B20NK50Z. I think there are only like two smd transistors left on that side of the board and they were both testing good. Ill have to double check them.

[dustman1747]

Re: HP-T5054 Samsung Plasma Screen Issues

Control boards are cheap for this set, may account for the vertical lines. Have you checked over your xsus carefully ?

And make sure you haven't damaged any of the mosfet via's on removal like I did because those mosfets are soldered at the top and bottom of the board.

I didnt do much checking on the X-sus because I tried replacing it with another board. The problems dont seem to be intermittent with both boards, like its unrelated to the X-sus. There is the possibility though that I got another bad board though.

[dustman1747]

Re: HP-T5054 Samsung Plasma Screen Issues

two smd transistors

It wouldn't let me edit my post but I meant surface mount MOSFETs

[dustman1747]

Re: HP-T5054 Samsung Plasma Screen Issues

Just replaced the last 6 mosfets on the Ysus. All of them are now new and the issue seems unchanged. Not sure what to tear into next.

[dustman1747]

Re: HP-T5054 Samsung Plasma Screen Issues

I was playing with the X-sus ribbon cables to the panel. It appears that if:

2 are plugged in the TV stays on and Vs is stable

3 are plugged in the TV power cycles as if the protection circuit is tripped

3+ plugged in the TV turns on shows pink blur and the power supply whines from being overloaded. Vs drops to about 196V.


Still sound like a Ysus problem or could it be Xsus or even the panel?

[freakaftr8]

Re: HP-T5054 Samsung Plasma Screen Issues

I honestly still think you have a Ysus problem. You're only mimicking the issue by disconnecting ribbon cables because the y sus is drawing so much current from the power supply that it's hard to keep without going into over current protection mode. Disconnecting the Xsus ribbons is allowing the power supply to sustain a level where its not going into over current protection.