LG 50 Inch Plasma 50PS3000 - Picture but no sound

[Easky15]

Im havin no luck at all with this TV, Its onto its 3rd power board now, Fitted new Power board there a few days ago after it was lyin in the garage for a few months, All was working for a day or so then heard a very loud bang from it, Just after the bang no real symptoms but picture slowly got darker then faded away completely and not tv just has sound but no picture,
Ive had a quick look inside it and cant see any components visably damaged, I was expecting to find a popped cap on on of the sustain boards but nothing, Only thing i found that i think may have caused it was a large dead spider, Would it be possible it could damage anything if it walked across a live component?

Ive read this is a common problem with these LG TV's, Would like to get it fixed as cheaply as possible, fired far too much money at this tv now,

[ReeceyBurger123]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Lol sounds like a game there, have you a multimeter ?

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Lol sounds like a game there, have you a multimeter ?

I do indeed sir, ;-)

[ReeceyBurger123]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Ok right do you know how to check DC voltages with it ?

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Yes, I only checked the Va and Vs so far, One said 195 on sticker on back of the panel and measured 195, other shown as 60 but measured 65 so i turned it down to 60 usin the adjustment screw but still same problem,

[ReeceyBurger123]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Well no need to check the Sustain voltages, mainly the lower ones like the 12v. Have you an image of the board you can trace out the audio amp to see if thats the cause of no sound ?

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

No man think ya misread the post, TV now has sound and no picture..lol ;-)

[ReeceyBurger123]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Ahh wait look at the title lol it says Picture no sound !

Ok so back to this properly, you seem to have the main supply voltages to the sustain boards meaning the Psu is good. Can I ask if you switch the Tv on in a dark room does the screen glow or is it totally black ?

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Ahh crap.. Sorry man my mistake..lol

ok the TV screen is completely off. not even blank black screen.

[ReeceyBurger123]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Ok right, so one of the sustain boards is failed, on the Y sustain (left hand board with buffer cards attached) and on the Z sustain (right hand board) there will be test points for certain voltages and what they should be running at. Theres a sticker on the panel which has a list of these voltages.

Use your meter to check the test points on them and let us know what you get. Main ones are:

-VSC
Zbias
Yup
Ydwn

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Zbias = 4.93v
Yup isnt there but theres a Sus-Up = 0.3v
Ydwn isnt there but theres a Sus-Dn = 1.17v
VSC = Initial voltage spike to arround 20v then drops to about -20 and rises until it finally levels off at about

Couldnt see a test point for VSC so that reading was got from 2 pins feeding the top buffer board labeled VSC

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Also no sticker showing what all voltages should be only Va and Vs

[ReeceyBurger123]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Hmm ok, have you tried unplugging just the top buffer only to see if you get lower half image ? Common issue on all Lg Plasmas is blown top buffer causing low sustain voltage. Also Vzbias is not right but will will check that later.

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

ok tried one buffer board at a time there and still nothing at all on the screen.

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Any other ideas what i can try next?

[ReeceyBurger123]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Right so you know that your sus voltages are low but Vs is good, so its possible its a control board fault or shorted sus boards.

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Right so you know that your sus voltages are low but Vs is good, so its possible its a control board fault or shorted sus boards.

Is there any further tests i can do to diagnose exactly which board is causing the problem here? Hate this 32 inch.. Want my 50 back..lol ;-)

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

?????????????

[ReeceyBurger123]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

Right sorry can you give me a restart if whats going on with the set ?

[Easky15]

Re: LG 50 Inch Plasma 50PS3000 - Picture but no sound

What ya mean give ya a restart? The TV has sound but no picture, Sorry i posted thread with wrong title, Symptoms were a big bang then picture slowly faded away to nothing, no backlight just completely dead screen but with HDMI in I can still hear sound.