LG Plasma 60pk950-UA no picture or sound

**tom66** · 12-03-2013, 11:40 AM

Re: LG Plasma 60pk950-UA no picture or sound

OK, we're close. It is either the Y-buffers or Y-sustain.

At this point please undo both connectors P104 and P105 on the Y-sustain board (refer to document for locations.) These connect to the buffer boards. Leave all screws in place. Then power on set and check these voltages. Are they as they should be?

NO:- Repair/Replace Y-sustain. Limited repair information available, no schematics, so replacement is advised, although some basic tracing can be done.

YES:- Replace Y-buffer(s). (Generally considered non-serviceable due to construction.) Locate which board is causing the fault. To do this try plugging in only one board at a time. There is a YB TOP and YB BOTTOM. Remember to isolate the connection between the two at all times. Check voltages. If the isolation of one board causes the voltages to come up, replace that board. (The panel may or may not work with the board removed. It could display half an image, no image, or just strange patterns.)

**clubberlange** · 12-03-2013, 11:52 AM

Re: LG Plasma 60pk950-UA no picture or sound

Originally posted by clubberlange

-Vy jumps between 10v-40v
Vsc jumps between 10v-30v

If I unplug p113,p114 and take the y-sus out of the equation my voltages on f801,501,301 are good. When the Y-SUS is connected my incoming voltage to the power supply drops to 60v.

**tom66** · 12-03-2013, 11:56 AM

Re: LG Plasma 60pk950-UA no picture or sound

At the moment, as I said, the power board is not under consideration because the voltages it is producing are all nominal. If this was not the case then I would suggest checking the power board, but it's working fine.

Be very careful when plugging in Y-sustain again. Wait a few minutes for Vs to drop below 50V before connecting it.

**clubberlange** · 12-03-2013, 11:57 AM

Re: LG Plasma 60pk950-UA no picture or sound

Originally posted by tom66

OK, we're close. It is either the Y-buffers or Y-sustain.

At this point please undo both connectors P104 and P105 on the Y-sustain board (refer to document for locations.) These connect to the buffer boards. Leave all screws in place. Then power on set and check these voltages. Are they as they should be?

YES:- Repair/Replace Y-sustain. Limited repair information available, no schematics, so replacement is advised, although some basic tracing can be done.

NO:- Replace Y-buffer(s). (Generally considered non-serviceable due to construction.) Locate which board is causing the fault. To do this try plugging in only one board at a time. There is a YB TOP and YB BOTTOM. Remember to isolate the connection between the two at all times. Check voltages. If the isolation of one board causes the voltages to come up, replace that board. (The panel may or may not work with the board removed. It could display half an image, no image, or just strange patterns.)

Sorry, kinda jumped the gun on that one. If I unplug p104,p105 the voltages are good. ShopJimmy has the Y-SUS and buffers in stock. Would you recommend replacing the buffers too?

**tom66** · 12-03-2013, 12:03 PM

Re: LG Plasma 60pk950-UA no picture or sound

I made a mistake in what I said above. The YES/NO are the wrong way around.

Voltages good when buffers isolated?

NO:- Repair/Replace Y-sustain. Limited repair information available, no schematics, so replacement is advised, although some basic tracing can be done.

YES:- Replace Y-buffer(s). (Generally considered non-serviceable due to construction.) Locate which board is causing the fault. To do this try plugging in only one board at a time. There is a YB TOP and YB BOTTOM. Remember to isolate the connection between the two at all times. Check voltages. If the isolation of one board causes the voltages to come up, replace that board. (The panel may or may not work with the board removed. It could display half an image, no image, or just strange patterns.)

Seems like the case "YES" applies to you. So try with only one buffer at a time. The Y-sustain doesn't need replacing.

These LG Y-buffers seem to be a common fault, seen several with this failure recently.

**clubberlange** · 12-03-2013, 12:07 PM

Re: LG Plasma 60pk950-UA no picture or sound

Originally posted by tom66

I made a mistake in what I said above. The YES/NO are the wrong way around.

Seems like the case "YES" applies to you. So try with only one buffer at a time. The Y-sustain doesn't need replacing.

These LG Y-buffers seem to be a common fault, seen several with this failure recently.

When you say isolate the buffers, do you mean remove the p106,p206 connector that jumps from one board to the other?

**tom66** · 12-03-2013, 12:15 PM

Re: LG Plasma 60pk950-UA no picture or sound

Is that the small white wire connection between them? If so, yes. Isolate that at the same time.

**clubberlange** · 12-03-2013, 12:22 PM

Re: LG Plasma 60pk950-UA no picture or sound

OK, something strange going on. I unplugged the white wire going between the buffers. Uhooked p104 and tested voltage and it was good. Hooked p104 and unhooked p105, tested and voltage was good. Hooked everything back up and voltage was good? Also I guess I need to know what voltage you want checked. Also what should I see for voltage on Vsc and -Vy?

**tom66** · 12-03-2013, 12:28 PM

Re: LG Plasma 60pk950-UA no picture or sound

The Vsc and -Vy are written on the plasma panel, see the documentation previously linked for how to read the PDP60R1 label.

If the Vsc and -Vy measure correctly with the buffers in place and all connections correct, you should be able to see a little glow from the screen.

**clubberlange** · 12-03-2013, 12:36 PM

Re: LG Plasma 60pk950-UA no picture or sound

Originally posted by tom66

The Vsc and -Vy are written on the plasma panel, see the documentation previously linked for how to read the PDP60R1 label.

If the Vsc and -Vy measure correctly with the buffers in place and all connections correct, you should be able to see a little glow from the screen.

Ok, its the lower buffer. With it unhooked the voltages are good and the top half of the screen has a faint white glow. Thanks a million for your help. Also is there a way to donate to the forum or to you for the great service provided?

**tom66** · 12-03-2013, 12:50 PM

Re: LG Plasma 60pk950-UA no picture or sound

Great, replace the lower Y-buffer and your TV should be fixed. You could donate a few bucks to the service manual's site in my signature (http://www.toms-service-manuals.com/) or buy some capacitors from badcaps.net for your next project. I don't know if topcat takes donations directly, but you could PM him to ask...

**CHOOKY** · 12-03-2013, 05:34 PM

Re: LG Plasma 60pk950-UA no picture or sound

Hi, my lg 50pg20d has same problem still not fixed yet but i can offer some info. Not so expert technician said it was a fault on z sus and changed 2 transisters which made the tv worse then i got no green/red switch on light..... Told him to put back original ones this was not the problem.
Hope this helps

**tom66** · 12-03-2013, 05:40 PM

Re: LG Plasma 60pk950-UA no picture or sound

Originally posted by CHOOKY

Hi, my lg 50pg20d has same problem still not fixed yet but i can offer some info. Not so expert technician said it was a fault on z sus and changed 2 transisters which made the tv worse then i got no green/red switch on light..... Told him to put back original ones this was not the problem.
Hope this helps

Please post in a separate thread. You have an entirely different model of TV.

**clubberlange** · 12-04-2013, 03:17 PM

Re: LG Plasma 60pk950-UA no picture or sound

Got my buffer board today and intalled it. -Vy,Vsc voltages good now. Still no picture. Any ideas?

**clubberlange** · 12-04-2013, 03:23 PM

Re: LG Plasma 60pk950-UA no picture or sound

Originally posted by tom66

OK, that's good.

See attachment.

With TV OFF and UNPLUGGED:
- Disconnect the blue highlighted cable, by pressing each clip gently and pulling backwards with minimal force.
- Place a wire link between the two holes marked in red.

Then plug TV in and turn on if it is in standby.

You may or may not see test patterns, but if you do, it indicates the main board is bad (not this board... the board with HDMI etc.)

Ok, I did this again and my screen starts changing colors. So I assume the main board is bad too?

**tom66** · 12-04-2013, 04:32 PM

Re: LG Plasma 60pk950-UA no picture or sound

Before you rule main board out make sure LVDS (cable between main and control) is seated properly both ends. Did the TV experience a power surge of some kind? It could have damaged the main board then taken out the Y-buffer, but that is quite rare.

Note: Main board is the one with HDMI on it.

**clubberlange** · 12-04-2013, 04:40 PM

Re: LG Plasma 60pk950-UA no picture or sound

Reseated both ends of LVDS. As far as a power sure I don't know. A while back the HDMI port on my DirecTV DVR burnt out and they assumed it was a power surge.

**newtothis** · 12-04-2013, 04:45 PM

Re: LG Plasma 60pk950-UA no picture or sound

Since there are test patterns and with the possibility it was hit with a power surge.. Mainboard failure

**clubberlange** · 12-04-2013, 04:46 PM

Re: LG Plasma 60pk950-UA no picture or sound

OK, Thanks again for your help.

**Hawkp123** · 11-01-2015, 12:46 AM

Re: LG Plasma 60pk950-UA no picture or sound

I don't mean to piggy back on anybody's thread but I am pretty new to this and can't figure out how to post my own thread so sorry but I have a lg 60pk 750 has no picture or sound any help would be great thanks

LG Plasma 60pk950-UA no picture or sound

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