LG50PA6500 No Display, Suspected PSU

[bboyzell]

Hi All

I have recently been given a LG 50PA6500 50" Plasma with the following problems

• No Display, Or backlight
• Audio is Ok, So i have been told by old owner

Possible Symptoms/Things iv noticed

• Noticable One off Click/Pop From the PSU When Power is plugged in
• Plasma instantly Powers Up, Doesnt go directly to Standbye
• Hit the Power Button and goes to Stand-bye
• CTRL Panel is Blinking Different Green Codes (Anyone have a guide for these,no luck finding on so far)
• Input Board has a Single LED glowing red.

Thinkings i have Checked so Far

• Run Screen With YSUS/VSUS Disconnect
• Preempted it being YSUS, so brought another one, this didnt make any difference, Actually the New Ysus Was Louder (buzzing)
• VA and VS both spot on with readings, VA-55 VS-205
• Inspected Top PSU FUSE F801 Not Blown, Constant Voltage of 280 (V-500)
• Inspected the Lower PSU Fuse F101 Not Blown, but Extermely low Voltage of 0.03 jumping to 0.13 with the Multimeter Set at (V-20)

Tools i have avalible are a Decent desolder/solder station and a Multi-meter

With the last Two Items on the list, Im thinking that the Bottom Fuse F101 Near the AC Plug, is fine but something that its connecting to is playing up but im unsure what.

EAX64276501 is the PSU thats in this system

Anyone have a suggestion of what i could test to see whats giving me low voltage to the F101 Fuse

[chrismurphy]

Re: LG50PA6500 No Display, Suspected PSU

[QUOTE=bboyzell;477646]Hi All

I have recently been given a LG 50PA6500 50" Plasma with the following problems[LIST][*]No Display, Or backlight
Plasma does not have backlights
[*]VA and VS both spot on with readings, VA-55 VS-205
Then the power supply is working and the fuse has not blown otherwise there would be no voltage for the z and y sus boards

Dont forget the voltage on the fuse is 240 AC

[tom66]

Re: LG50PA6500 No Display, Suspected PSU

Check the Vsc and -Vy voltages on the Y-sustain board....

I hope it's not another bad LG plasma panel killing the buffer board.

[bboyzell]

Re: LG50PA6500 No Display, Suspected PSU

Check the Vsc and -Vy voltages on the Y-sustain board....

I have found VSC and -VY Resistors on the ysus, is that what you are refering to?

Am i able to measure it with my Multimeter?
I own the following one

[tom66]

Re: LG50PA6500 No Display, Suspected PSU

Yes, measure across them on the 200V DC range.

[bboyzell]

Re: LG50PA6500 No Display, Suspected PSU

Yes, measure across them on the 200V DC range.

Thanks

"VSC" Is giving me a constant Variable Reading of between 03.3 to 00.0

"-VY" Is Giving me a Reading that is constantly switching With Value similar to the following 14.x - 22.x - 34.x(Highest seen)

Just Came across this thread again.
LG 50PA6500 - Sound no Picture
https://www.badcaps.net/forum/showthread.php?t=30067

[tom66]

Re: LG50PA6500 No Display, Suspected PSU

OK, that's not a great sign to be honest. Can you remove the top Y-buffer board; this is the top most board connected to the Y-sustain. Note, you'll have to unscrew the board and pull it out from the white connection blocks. You don't have to remove the orange ribbon cables.

Then, do you get half an image?
Do the -Vy and Vsc stabilise?

[bboyzell]

Re: LG50PA6500 No Display, Suspected PSU

Then, do you get half an image?
Do the -Vy and Vsc stabilise?

Ok, Removed the Upper Buffer Board.
I am now getting display on the lower half of the Screen

-VY is Running at a constant 184.x
VSC is running at a Constant 145.x

I will visibly inspect the top buffer board and see if i can see anything foul

[bboyzell]

Re: LG50PA6500 No Display, Suspected PSU

I have now just tested out the Upper Buffer Board
I tried it the following ways.

No Lower Buffer Board + Upper Buffer Board + Panel Connected = Poor Voltage
No Lower Buffer Board + Upper Buffer Board + Panel Not Connected = Poor Voltage

My Conclusion if a "Faulty Upper Buffer Board" Sadley it seems to be the more costly Than most the the other boards on the Plasma

Proceeding to Do this
Testing Y-Buffer Board for short Circuits
https://www.youtube.com/watch?v=51SZ...Y&noredirect=1

Also Note:

I have Inspected All 4 of the Ribbon Cables that connect to the upper buffer, all look to be in good condition

[tom66]

Re: LG50PA6500 No Display, Suspected PSU

Your panel is bad. 99% guarantee it. Sorry.
The tear is VERY hard to see. You have to take the TV frame off to be sure.

Same TV, UK spec model (50PA650T) ended up scrapping it due to bad panel.



That tiny dimple on the right of the ribbon? That's where they tear. That seems to kill the top buffer boards.

[bboyzell]

Re: LG50PA6500 No Display, Suspected PSU

Your panel is bad. 99% guarantee it. Sorry.
The tear is VERY hard to see. You have to take the TV frame off to be sure.

Same TV, UK spec model (50PA650T) ended up scrapping it due to bad panel.

Upon a Closer inspection, i think i have found a Crease on the ribbon cable nearest to the top of the Plasma, it looks to almost be at a right angle compared to the rest of the smooth flowing cable

I take it them its not worth procedding with trying to fix this unit, replacing the upper buffer would just result in the new one being shorted out by the Panel (wasting $70+)

Thanks alot for you time & Input Helping me with this Tom!