LG 50" Plasma 50PS30-UB powers on, no picture, no sound

[niblettr]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

also, see attached

[vinceroger69]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

should the test point pins be bridged before you even turn the set on? or dosnt it matter?

[niblettr]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

No, just connect everything up like normal first.

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Do you have access to an oscilloscope? If so, check for pretty waveform going from control board to Ysus board.

I do not unfortunately.

As for the power wires on the board, I will check it tomorrow after work

If the voltages read low would you say bad power supply? and if voltages are okay, then bad logic board?

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

It's actually the one with white wires. First 4 pins on left read 5.11v and the others are ground which appears to be correct.

[niblettr]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Try isolating the Z sus board then try power up tv. Do you see any change?

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Try isolating the Z sus board then try power up tv. Do you see any change?

If you are referring to simply unplugging power from the z sus, then yes I have already tried that and nothing changed. But I will go try disconnecting everything from it to double check

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Try isolating the Z sus board then try power up tv. Do you see any change?

I unplugged both wires going to the z sus board and no change. I feel like we are at a point where I should start trying to replace parts now

[Alastair E]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Aye--Go on, Replace parts!

But--Which Ones....?

Only logical fault-finding will tell ya! Can you confirm ALL the voltages are Correct?

These are--

Vs, Va, VSC, -Vy and VZBias.--Not all of these are measured with respect to chassis, so confirm with the manual the correct test-points, but are normally marked on the boards.

Your fault--(To illogically just replace parts) could be in no particular order-- the Control-Board, the Y-SUS, the Z-SUS or the Mainboard,--Oh yes, the PSU and the Buffer-board could also be at fault, Or the panel itself

You takes your pick and pays the price!....

Confirm also, you have Va on the lower panel address-board.

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Aye--Go on, Replace parts!

But--Which Ones....?

Only logical fault-finding will tell ya! Can you confirm ALL the voltages are Correct?

These are--

Vs, Va, VSC, -Vy and VZBias.--Not all of these are measured with respect to chassis, so confirm with the manual the correct test-points, but are normally marked on the boards.

Your fault--(To illogically just replace parts) could be in no particular order-- the Control-Board, the Y-SUS, the Z-SUS or the Mainboard,--Oh yes, the PSU and the Buffer-board could also be at fault, Or the panel itself

You takes your pick and pays the price!....

Confirm also, you have Va on the lower panel address-board.

As I posted earlier in the thread all the voltages I tested were normal. No idea how to test the "lower panel address board", no one has mentioned that yet. I'm just getting frustrated that this tv is not a quick/simple fix like I was expecting.

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Bump

[reaper57]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Bump

Check all of the fuses, especially the ones on the power supply, while the TV is off and has been unplugged for a minute or two.
Also, can you post a picture of the power supply?

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Pic attached. All the fuses I can see test okay (none reading as OL)

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Another pic

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Whatcha thinking?

[reaper57]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

I recently had a similar plasma with the same power supply, the problem there where the two mosfets marked in red in the picture bellow. They are actually a common failure on this power supply. Check the resistance between the legs, there should be no shorts.
P.S. Are you sure that the blue fuse, left of the mosfets in red, is reading 0 ohms and not something like 300-1k ohms?

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Without removing the board, none of those 3 appear to be showing OL. Would you suspect power supply? And was yours having the same symptoms?

[douellette88]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

Fuse was at 0

[Hamie]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

I sincerely doubt your power supply to be at fault.
You have VS, VA, 5v standby etc.
Along with vzb, vy and vsc

Your problem is more likely to be the control board or the main AV board.

It may also be, as suggested earlier, the lower address boards are not getting voltages or are faulty.
Or the panel itself.

Going by the fact it's an LG I'd hazard a guess at the mainboard.

[reaper57]

Re: LG 50" Plasma 50PS30-UB powers on, no picture, no sound

I sincerely doubt your power supply to be at fault.
You have VS, VA, 5v standby etc.
Along with vzb, vy and vsc

Your problem is more likely to be the control board or the main AV board.

It may also be, as suggested earlier, the lower address boards are not getting voltages or are faulty.
Or the panel itself.

Going by the fact it's an LG I'd hazard a guess at the mainboard.

You're probably right, I must have missed the part about the VS and the VA voltages. Btw, mine also had 5V standby, but that's probably because the blue fuse on my board was at 300-1k ohms.