Author Topic: LG 50PZ950T - No picture, sound ok.  (Read 199 times)

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Turnip

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LG 50PZ950T - No picture, sound ok.
« on: November 02, 2018,09:32:30 »
Hi folks,

Got one in where cust said he needed turn set on and off several times before a picture would occur - Sound fine. Now picture doesn't appear at all. Wonder if anyone has ideas ? - Thanks - Chris.

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LG 50PZ950T - No picture, sound ok.
« on: November 02, 2018,09:32:30 »

downunder

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #1 on: November 03, 2018,03:03:37 »

Hi Chris,

I usually start off by ohms checking Vs to ground. If shorted, unplug Z-SUS and check again. If still shorted, Y-SUS is the culprit.
I'll upload the Trump version of the service manual to the forum, but there's probably not much that will be helpful.


Bruce



Turnip

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #2 on: November 03, 2018,08:21:50 »
Thanks Bruce,

Turned it on this morning - Normal sound and picture. Tried again - Just sound. Tried again, nothing at all so left it on for a half hour, rewarded with normal sound and picture.

Whilst it wasn't working, measured all voltages on power board - All OK. As its an LG - Maybe cook the SSB ?  - Chris.

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #2 on: November 03, 2018,08:21:50 »

downunder

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #3 on: November 05, 2018,02:11:18 »

Hi Chris,

When its n/w, are you able to bring up test patterns by shorting the copper pinholes on the control board?

Bruce

Turnip

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #4 on: November 05, 2018,11:32:07 »
Hi Bruce,

Noted when the set gives a picture the Led on the control board flashes four and four. When just sound, it doesn't flash at all.

Checked regulators and both read 3.4v out whether picture or not. Manual suggests if Led doesn't flash there's an issue on the control board where an oscillator isn't working.

Dubious, as at times don't even get sound, so feel the control board isn't the issue. Itching to cook the SSB - Chris.

PS - Manual gave no info about shorting pinholes for test patterns. Noticed a couple but unsure.
« Last Edit: November 05, 2018,11:47:59 by Turnip »

downunder

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #5 on: November 06, 2018,02:54:10 »

Two small pinholes. usually at the 4 o'clock posn. wrt centre of large IC, may be marked as R51  - R52.


Bruce

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #5 on: November 06, 2018,02:54:10 »

Turnip

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #6 on: November 06, 2018,10:04:17 »
Hi Bruce, spotted them - R51/R52 as you suggested.

Currently the set works, so will wait awhile see if gets that Led flashing 4 x 4.

Still wondering why at times I get no sound either, as doubt the control board controls audio, seems more SSB - Chris.

downunder

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #7 on: November 07, 2018,02:10:01 »
Aye, that sounds like the main board (ssb as you and Philips like to refer to it as).

Maybe time for some kitchen duties, if only to prove the point.

Bruce

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Re: LG 50PZ950T - No picture, sound ok.
« Reply #8 on: November 07, 2018,11:09:59 »
Hi Bruce, did so then shorted the holes getting just sound. Off to another LG 50 Plasma which used to cut to S/by every few days. Replaced both resistor chains and a couple of chips - Seems ok at the moment but won't screw the back on quite yet.

Back to the other one where got sound and interesting test screens - Snipped the link then got sound only. Tomorrow will get sound and picture 'till I turn it on again to get just sound.

While ago a keen Philips man, 'till the rental company went poop as didn't realise Japan made reliable sets not needing an average of three calls a year to replace crap UK sourced components.

Can't recall that the Philips G500 had a SSB as nothing in those days was small or light.

Think might cook the control board tomorrow as the wife is out 'till lunchtime - Chris.

« Last Edit: November 07, 2018,11:13:47 by Turnip »

 

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