Lg 50pt250u plasma tv

[Andrew F. Ali]

I have this PLASMA TV on my workbench for repair. When plugged in to the 120Vac I hear the relay click ON then a few seconds later click OFF. The PSU self-test proved the PSU is OK and Vs, Va,M5V, 17V, etc are where they supposed to be at. The Vs goes from the PSU to the Y-sus Bd. and from the Y-sus Bd to the Z-sus Bd. With the Y-s connected and the Z-sus Bd disconnected the Vs is correct at 205Vdc. I deduct that the Z-sus is faulty and pulling down the Vs supply.
Z-sus Bd.: EAX63529101 EBR71736301
Y-sus Bd.: EAX62846401 EBR7183E6301

My question is: With the Z-sus disconnected and the Vs and M5V stable on the Y-sus, should I be getting Vsc produced on the Y-sus or would that only come up with the Z-sus connected and working?

[Andrew F. Ali]

Re: Lg 50pt250u plasma tv

Anybody??

[Biruslapio]

Re: Lg 50pt250u plasma tv

first thing,check Y-buffer boards for shorts or blown ICs.
if no problems there,keep Z-SUS disconnected,check Y-SUS VSCAN and -VY,if it does not produce these voltages,logic board may be disarming the set because Z-SUS is not present,then you'll have to remove and check the fuses,IGBTs and 2Watts resistors on Y and Z boards.

[Andrew F. Ali]

Re: Lg 50pt250u plasma tv

Thanks for the reply Biruslapio. IGBTs OK on Y-sus Bd. Y-buffer has no shorts. Thanks for the reasoning why Vscan not producing, as Z-sus Bd. disconnected Logic Bd. disarming the set.

[Biruslapio]

Re: Lg 50pt250u plasma tv

Take a look at these red circled points on your Z board,if none of the SMD/PTH resistors are open,or any IGBTs reading low resistance between the pins,then do the same to Y board.

[Andrew F. Ali]

Re: Lg 50pt250u plasma tv

Thanks a lot!!

[Andrew F. Ali]

Re: Lg 50pt250u plasma tv

IBGTs on the Z-sus shorting out. I'm surprised they didn't blow the fuse. I can get a used board. I think I'll go ahead and buy it. The Y-sus Bd. seems OK. Thanks for the advice. I'll update when I install the 'new' Z-sus Bd.

[HSVHEL]

Re: Lg 50pt250u plasma tv

IBGTs on the Z-sus shorting out. I'm surprised they didn't blow the fuse. I can get a used board. I think I'll go ahead and buy it. The Y-sus Bd. seems OK. Thanks for the advice. I'll update when I install the 'new' Z-sus Bd.

Hi Andrew
What was the outcome of your repair here, i believe i may have a similar condition with my Zsus board.
With it connected the unit will power on, then return to stand by.
With it removed, the unit will power on and remain on, but produce no picture or start backlight