Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Use a 10X probe, but yes, you can hook up your scope to the outputs to see what you get. Bonus points available if you can figure out how to set up the ramp trigger to get a stable display...

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Oooo Challenge accepted!!!

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Just make sure your probe is on 10X or you could damage your scope (it's unlikely, but possible.) This is because older LGs have a peak excursion up to 450V which exceeds the 300V input of your scope except in 10X mode.

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Got it...

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

That means the switch on the probe.... and set the scope to 10X... Read the probe's manual to learn its maximum ratings in both modes (IIRC it's 300V in 1X, 600V in 10X)

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

OK, still reading up on setting the Rigol.. But I DID check the ZBias voltage on the X-SUS board, following the instructions in that manual..

1.) Place DC Volt meter on VZB TP (Top of R7 to Gnd).

I got a voltage of 77v +/- 1.. According to my sticker, the ZBias should read 100v

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

That's quite low and could cause some minor picture distortions, can you try adjusting it up?

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Lemme give that a try...

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

90V is all I could adjust it to. That is using the VR41 Z-Bias adj all the way counter-clockwise

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Here is the -VY reading, which according to my sticker, should also be 100..

It's -44v

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Before I actually measure VSC, I wanted to confirm the Manual's instructions..

That I measure across C14...

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Try without buffers connected, I suspect there is a short on one of them....

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Measuring the VY as in #30..

-138v +/-

EDIT: Or did you mean measure the VSC across C14 as shown in #31??

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Measure Vsc too, that's the primary voltage supplied to the buffers (the connections to the buffer include wave out floating ground, which is the sustain waveform, then a voltage Vsc which floats on top of the wave out floating ground.) When buffers short they usually short across Vsc.

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Measure Vsc too, that's the primary voltage supplied to the buffers (the connections to the buffer include wave out floating ground, which is the sustain waveform, then a voltage Vsc which floats on top of the wave out floating ground.) When buffers short they usually short across Vsc.

With the buffers plugged in or unplugged, I get 130V when my meter is connected as shown in #31

[Shinju]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Can you provide some photos of your buffers, top and bottom and IC side and bottom side?

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Oh, missed that, that was power off? 130V with power on is ok, -Vy needs to be tested from -Vy point to chassis ground.

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Oh, missed that, that was power off? 130V with power on is ok, -Vy needs to be tested from -Vy point to chassis ground.

Yea, that was power on

Lemme get the VY reading

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

VY is -133v with the buffers plugged in...

Wierd.. Above it was -44... Maybe I had the wrong ground

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Still need the buffers pic???