lg 50pg30

[gdawg]

Just wanted to start off by saying what a great forum this is. Fixed a lot of tv's just by reading. Ok, I have a 50pg30 lg that I am having trouble diagnosing. Sorry my camera is down so cant post any pictures. If I power up the tv it stays on and the panel primes but no display. I have all the right voltages Va, Vs, Vsc. If I disconnect the upper buffer, then the lower part of the screen will display vertical lines in bands and they change in size and color depending on what input, menu, channel, volume I push on the remote. If I put the upper buffer back on, it goes back to no display at all. I thought about buying an upper buffer, but I am concerned it may be the y sustain. I dont have a scope so I thought I would ask for anybodys help. I also checked the transistors on the heat sinks and one group of transistors read Vs voltage, the other group flashes over load on my meter.

[MagicSmoke]

Re: lg 50pg30

Test upper buffer as shown here https://www.youtube.com/watch?v=51SZsfH60EY

Then test bottom just to be sure. If they test OK them Y sus is suspect.

[gdawg]

Re: lg 50pg30

Thanks for the reply. I wish my camera was up and I might have to wait till it is. With an ohmeter the buffers check the same. These have the two tabs that stick out of the buffers and plug into the sustain. It has a big pad for grounds and a bunch of smaller pads. The black probe on the ground and the red on the smaller pads shows every other as a ground, I saw a post before from tom66 and he mentioned something about odd even.. I thought maybe thats why every other pad is a ground, but both upper and lower test the same, The pads that read are in the mega ohm range.

[gdawg]

Re: lg 50pg30

I think I have a picture of the buffer. I never put attachments before but I guess it worked. I was swaying toward the sustain board but it was a little weird how it responded by removing the upper buffer

[gdawg]

Re: lg 50pg30

I tried to edit but dont know if it woked

[gdawg]

Re: lg 50pg30

Just an update- I took a chance and replaced the upper buffer and had a good picture on the top half but had the lower half had horizontal lines like every other line. I thought it was the ribbons and reseated them numerous times and had no change. So off to find a lower buffer and hope it works. This is a 1080p plasma so the top half looked great.

[pk7tanner]

Re: lg 50pg30

Consider yourself lucky. Mine had a cascade failure when the buffer went it took down the ysus, which in turn took out the zsus. Needless to say, I never fixed it.

[gdawg]

Re: lg 50pg30

Just a reply. replaced the lower and picture was great. After testing all the inputs found I had no digital audio thru hdmi or optical. So looks like main board problem. I get audio for about 10 seconds and then gone. Think I will sell it as is. All analog audio works fine. I have about $250.00 into the tv and its maybe worth that much. I guess chaulk it up to experience