LG 50PK550 Plasma Clicking Problem

[jun3280net]

Hello there,

I'm a complete beginner, so I apologize in advance if it takes me a bit longer to digest some of the instructions and technical aspects of troubleshooting. That said, I'm excited to post as I've seen how helpful the members at badcaps are.

My LG 50PK550 plasma television recently just began to experience the dreaded clicking problem, where the TV will immediately shut off or go into standby mode upon power up.

I can confirm I get a grey flash upon power up, and the tv screen will go black 1-2 seconds later. From time to time, I can get a sustained picture for 5-10 min before it shuts off again.

I've ready many posts for variants of the LG Plasma PK540, PK590, etc, which suggest it's due to a bad resistor on the upper right side of the power board. Most of the boards I've read consist of 2 x 5W22 Ohm resistors. My board has 3 x 5W10 Ohm resistors. I measured them, and they seem stable at 10 Ohms. I swapped out the one resistor that seemed to fluctuate, but no difference. I tested the resistor afterwards, and it held stable at 10 Ohms.

When the boards are connected, the TV will turn on for a couple seconds, flash “grey”, and then shut off. I am unable to measure the voltages.
To troubleshoot, I disconnected the Z-SUS and Y-SUS from the power board, and I was able to measure the voltages. They are as follows :

On the power board (A)I measured :
P811 to Z-SUS (B) :
(M5V=5.4V, M5V=5.4V, GND=0V, VA=60.8V, VA=60.8V, GND=0V, GND=0V, NC=0V, VS=202V, VS=202V)

P812 to Y-SUS (C) :
(M5V=5.2V, M5V=5.2V, GND=0V, VA=60.7V, VA=60.7V, GND=0V, GND=0V, NC=0V, VS=202V, VS=202V)

P114 connector (bottom of Y-SUS) :
(60.2V, 60.2V, 60.2V, 60.2V, 0V, 0V)

P813 to Main Board (D) :
(17.1V, 0V, 5.2V, 5.2V, 0V, 0V, 5.2V, 2.3V, 3.2V)

When I connect just the Z-SUS (B), and power up, there is no picture, but the sound is on. The device is able to sustain power.
When I connect just the Y-SUS (C), and power up, it flashes “grey” and shuts off shortly after.

When I connect just the Y-SUS (C) – but remove the connections to (1) – the unit powers up, flashes a red screen for a few seconds and then shuts off.

Any other ideas as to what might be the problem - or other items to test? Thanks in advance for your insight and assistance.

Thanks,
J

[tom66]

Re: LG 50PK550 Plasma Clicking Problem

Just above "A" there is a sticker with a part # e.g. "Model: PDP50N7####" printed what is yours?

[jun3280net]

Re: LG 50PK550 Plasma Clicking Problem

Hi there,

It looks like PDP50R10000.

Thanks,

J

[tom66]

Re: LG 50PK550 Plasma Clicking Problem

Your panel is covered in this document


Find the 50R1 panel.

Of note is the section on -Vy and Vsc testing, please perform this test while set operates and when it malfunctions.

[jun3280net]

Re: LG 50PK550 Plasma Clicking Problem

Thanks for the link to the document tom66. I've been unable to get to my parents place to test their television, due to a busier than normal work schedule this past week. I'll try and follow your guide later this week - and post my findings then.

In regards to this section - for the Pre-Heat - does that mean leave leave the TV on for 10 min? If so, it seems hit and miss as usually the TV shuts off after a few seconds. Does that mean I should disconnect the Y-SUS to ensure the TV remains on for 10 min - before reconnecting it again to test?:

"50R1 VSC, -Vy ADJUSTMENTS
PREPARATION:
PROCEDURE: (See figure below for locations)
1) Adjust –Vy VR302. Measured across –Vy TP R334.
Match your specific Panel’s Voltage label ±1V.
1) Pre-Heat unit for at least 10 Minutes
before making adjustments.
Vs and Va adjustments complete.
2) Place unit into White Wash from the
Customer’s Menu for all adjustments.
3) Be sure to use all adjustment values as
indicated on your panel’s voltage label in
the upper left of the panel.
2) Adjust VSC VR301. Measured across VSC TPs R324.
Match your specific Panel’s Voltage label ±1V."

Cheers