Lg 60PS60 no image but pdp glows

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

Anyone know where ii can read VE voltages on the ysus?

[Andrew F. Ali]

Re: Lg 60PS60 no image but pdp glows

hopefully tom66 will see this thread and have a idea what the issue maybe

+10

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

Yes because this one has me stumped I'm almost certain that the signal somehow is being muted by some kind of short By the vertical address buffers

[vinceroger69]

Re: Lg 60PS60 no image but pdp glows

Hopefully tom66 will see this thread and have a idea what the issue maybe

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

However I have noticed that if I disconnect the far left C board from the logic board I get a flashing array of vertical stripes on the far left side of the panel. The other 2 c boards connected to the logic board, because of course there's 3 of them in a row across the bottom of the panel do not show any symptoms if those are disconnected from the logic

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

If the logic board was faulty I should not be getting waveforms at the buffer boards depicting the levels of voltage change in the panel where it is carrying the signals into the screen this would lead me to believe the logic board is doing its job however if there is no VA output from the bottom C buffers I don't believe there would be an image As it cannot be carried vertically across the screen. Is that sound correct? I have good VA and VS voltages coming into both Areas of the panel

[vinceroger69]

Re: Lg 60PS60 no image but pdp glows

your original and replacement logic boards both faulty?

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

This is precisely what I am thinking as well. I do not believe the main board is at fault due to the fact that I have initiated on 2 different logic boards the test patterns and disconnected the main board from the loop meaning pulling of the LVDS cable. I can hear the sustain boards going through different frequencies as it should be displaying the test patterns on the screen.

[Andrew F. Ali]

Re: Lg 60PS60 no image but pdp glows

The Ve voltage erases the previous scan so that there would be no retention of the previous picture on the screen. Leaving me to wonder now if the screen itself has some problem and question the Main Bd.

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

Getting back into this on the Y main I have no output for IC905. Hard to scope out without schematic however although I reassessed all voltages and they are all present.

The only thing in question is the last number on the voltage setting label after NA it States 105. Would that be ve? I cannot side a task point for VE on the Y main

Like I said I can scope the waveform outputs on the buffer boards and see that I'm getting some signal

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

No. The screen remains a grey raster. No image

[Andrew F. Ali]

Re: Lg 60PS60 no image but pdp glows

Were you actually seeing the patterns on the screen as it went through the pattern generator???

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

Logically it would seem that the VA buffers are not getting any signal however I can remove the power to the VA from the Y main and get the same symptom. Although VA is getting the proper 68 or so volts DC.

This is what led me to think that the logic board was faulty however it is not

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

I have VE and VSCAN. Also on the logic output of the Y main to the buffer boards I am getting waveforms there as the logic cycles through auto gen patterns.

The PDP panel Appears primed and ready as I am getting a grey raster. Just with no image.

[Andrew F. Ali]

Re: Lg 60PS60 no image but pdp glows

So then there is no Ve and or Vscan voltages??

[freakaftr8]

Re: Lg 60PS60 no image but pdp glows

Yes it appears that all these voltages are present. What I sighed interesting on the Y board is there is a small transformer And the mosfets in that area is registering 0 v. This transformer is either for the V set up set down or -vy

[Andrew F. Ali]

Re: Lg 60PS60 no image but pdp glows

Is the PSU producing all the necessary voltages? Like M5V, Va, Vs, 17V, 12V and 3.3V generated from the Control Bd to the PWBs at the bottom???

[freakaftr8]

OK so this one presents an interesting symptom I got this in last night and PDP panel lights but no image and I have ruled out mainboard as I tried to jump test patterns on logic. I'm getting data information to the buffers I can see voltage fluctuations as you can hear the resonant sound of the sustained boards change while it's going through the pattern generator. However still no image. I have seen others replace the Y main to fix the issue but I'm trying to figure out how this is a problem. I've gone through the normal run of checking resistors and fuses to no Avail.

Y main is EBR55492901

I replaced the logic board anyway just in case. No avail.

Also measured all voltages. All good. Any ideas?