lg 50ps3000 flaashes then screen goes off

[tom66]

Re: lg 50ps3000 flaashes then screen goes off

That circuit with the adjustment could have a short circuit. There's a repair kit:

http://www.ebay.co.uk/itm/LG-50PS300...item417bcc2e87

which includes some FETs, resistors, etc. There may be a part listing elsewhere.

That is for red pic - i.e. dead Z-sustain Vzb and other components. The fault may be limited to those heatsinked transistors near Vzb adjust on Z-sustain.

No schematics, though.

[wreksta]

Re: lg 50ps3000 flaashes then screen goes off

Tom I fitted that kit I have no shorts all connections are made so what else could could I check plz
I can tell you this that ceramic resistor in repair kit would light up and make a frazzling noise like a short but I replaced with original one I took out and I didnt get that short or lighting up

[tom66]

Re: lg 50ps3000 flaashes then screen goes off

Picture of the Vzb adjust area? You will probably find a FET on the nearby heatsink is short. The way most plasmas Vzb work is by linear regulation of Vs - they drop voltage across a transistor, which produces a small amount of heat. If transistor shorts, the Vzb = Vs minus a small drop due to resistance (that ceramic resistor, and some other parts.)

[vinceroger69]

Re: lg 50ps3000 flaashes then screen goes off

Tom I fitted that kit I have no shorts all connections are made so what else could could I check plz
I can tell you this that ceramic resistor in repair kit would light up and make a frazzling noise like a short but I replaced with original one I took out and I didnt get that short or lighting up

does the original resistor you put back in test ok and not gone open circuit?

[wreksta]

Re: lg 50ps3000 flaashes then screen goes off

Original resistor tests fine mate now I cant get ysus to fire up im sure it did with zsus disconnected could high ve have killed the ymain if so what to test on y for diagnosis ? Thanks

[tom66]

Re: lg 50ps3000 flaashes then screen goes off

Vzbias / Ve is independent of Y-main. However, running it on extreme brightness for too long could have damaged the Y-main from too much power usage. Standard checks: IGBTs/FETs on heatsinks and -Vy/Vsc voltage (see panel diagnosis sheet I linked previously.)

[wreksta]

Re: lg 50ps3000 flaashes then screen goes off

Thanks will check in the morn

[wreksta]

Re: lg 50ps3000 flaashes then screen goes off

Funny thing tom I can remember now the tv would stay on with a very very grainy red hazy pic right until I switched input to hdmi then nothing except the flash when powered