Re: LG 50PA5500 Good sound but picture barely visible



This is a follow up to my previous post. I could not find a point labeled "Vzbias". I found one marked "VBZ" (across R412) with a voltage of 148 vdc and one marked "zbias" (at pin 8 of connector p101) with a voltage of 2.14 vdc. I attached some pictures of the entire zsus board and close ups of these points. I hope this helps....

Re: LG 50PA5500 Good sound but picture barely visible

I measured across a resistor marked VZB near the top of the board. I'm getting 136 volts at first check. After about a minute it's reading 148 and seems to be holding there.

Re: LG 50PA5500 Good sound but picture barely visible

Thanks Tom66, I do have a digital multi meter. I've also visually inspected that board but see no obvious defects such as bulged caps or burnt resistors.

Tv just over I year old failed suddenly, no picture at all. The TV was transported about 200 miles from New jersey to Pennsylvnia and failed about a week after we placed back into service. I had it diagnosed at a repair shop but decided not to fix because of cost. Shop said problem was "Upper Y Drive". I replaced upper Y buffer; still no picture. Next replaced "Ysus" board and now have good sound with complete but barely visible picture. Brightness and contrast controls seem to function but have little effect at improving brightness of picture. Also screen has black speckling...

Re: New Members - please post your introductions here

Hi. My name is Dave. I'm a retired electrical engineer with 4 plasma and 2 LED tv's. I don't have any formal training in electronics repair but I'm hoping to learn enough on the forum to service these myself when necessary. Thanks in advance for all your help.