LG PDP 50x3 MAL Discharge Trobleshooting

[AncientOne]

Dear brilliant experts,

I am stuck troubleshooting an HP 5060N TV, fabricated in 2006.

It uses an LG PDP: PDP50X3R010

A friend gave it to me after it broke. Over a period of two weeks the symptoms went from first appearance, to intermittent appearance, to appearing at all times.

When the fault was intermittent, the TV picture would start out perfect, then after a while the entire screen would show the symptom as in the pictures in the blink of an eye. Then, after turning the TV off and letting it rest for 15 minutes, it would start up showing a perfect screen again, only to fail after a while.

Now, when I turn the TV on, it always goes through the same sequence of images, similar to those in the pictures. I imagine that it is looking for a signal source. When I press the MENU or INFO buttons, different images are displayed. This leads me to believe that the TV is attempting to display specific screens, but that the image is messed up.

I have read the information in the LG PDP model service manual, and this type of image seems to be what they describe as a MAL discharge problem.

Unfortunately, they say that it could originate in several places: The two Y Drive boards, the Y sustain board, the control board, corrupted software on the control board, or the z sustain board.

Can you assist me in identifying the faulty board(s) and possibly even the faulty component?

The specific boards are:

6871QCH059B CTRL HT50065A009059
6871QYH039B YSUS
6871QDH088A YDRVTP
6871QDH089A YDRVBT
6871QZH044C ZSUS
3501Q00200A REV A S/N SO06516334 SONY Power Supply

Many thanks.

Yours in enthusiasm,

AncientOne

[smartjohn]

Re: LG PDP 50x3 MAL Discharge Trobleshooting

I have this same set and am working on a similar problem. The large vertical white bar usually points to a problem on the Y-sus board (large board on the left side) OR the two buffer boards (with flat ribbon cables). I suspect my set is experiencing a problem on the Y-sus. When the set is on try, tapping on (with something insulated!) the two large aluminum heat sinks on the left side (facing the rear). These are the IPM modules which almost always are the problems with these TVs. I have had the ones on the RIGHT SIDE fail also. You may want to give those a light tap as well. good luck! I let you know if I get mine working also.

[Alastair E]

Re: LG PDP 50x3 MAL Discharge Trobleshooting

MOSFETS on Buffer-Board S/C.

There's three or four, you'll find one short--best replace the lot.

[smartjohn]

Re: LG PDP 50x3 MAL Discharge Trobleshooting

Yep, sure enough, the bottom buffer had all 3 shorted. 46N15 N-Channel mosfet 150V 45.6A. I pulled the lower board and I am stilling getting the power supply cycling, so I guessing something is still bad on the Y-sus. I replaced the yppd-j015c IPM but not the other one. What should the resistance be on the Vs line to ground?

[Alastair E]

Re: LG PDP 50x3 MAL Discharge Trobleshooting

many K ohms after caps charge...

[smartjohn]

Re: LG PDP 50x3 MAL Discharge Trobleshooting

Great news. I went back over my changes and double checked the yppd-j015c I had replaced on the y-sus board thinking this was the vertical bar problem. Turns out the module i used was now shorted. I replaced it with the one I pulled and Bingo! I got the upper half of the screen working perfect! I replaced all 3 of the 46N15 MOSFETs on the lower buffer board (6871QDH088A). I bought the non_SMD version and tweaked it to fit. (they were a buck cheaper!)

[ReeceyBurger123]

Re: LG PDP 50x3 MAL Discharge Trobleshooting

Good work