I don't think it would be that easy to test it with a dummy load as it has three ribbon connectors so could be complicated trying to give power to it. Would be disappointing if you were right and another board is faulty of the plasma screen itself as are drawing the extra current that is switching off the psu.
On occasion I have heard of the plasma screens themselves giving out so that is a real possibility. If there is a short elsewhere, well that could be too, that's why I ordered the psu board just to give it a go, but they cheated me and sent me a beat up used one instead of a new one.
Apples and oranges, buuut, my LED backlit TV stopped working and I wasn’t getting voltage at the power supply output, bought a used PSU and same thing happened.
Turns out it senses when one of the series LED lights goes out and shuts down. Bought some new LED strips from Shopjimmy.com and it’s better than new.
Could be something downstream.
Shame you can’t take all the tubes down to the drugstore tube tester or clean/replace the tuner knob. (sorry, joke for old people)
look for a short to ground on the va and vs lines.
if you find one unplug ysus from the power supply.
if still there unplug zsus.
y=big board on left as you are behind set.
z=the one on the right.
if no short leave va,vs unplugged from power supply and power it up.
measure from ground to va,vs.
if nothing possibly that section is not being commanded on or blown up.
or apfc not running and that section is in uvlo.
apfc output is at the 2 big caps on their side and is around 400vdc
oh and big warning!
these power supplies are dangerous due to both high voltages and high surge current due to big filter caps on va and vs.
apfc is around 400vdc and backed up by big caps too.
Thanks snakebite will give it a try. Do the big caps still retain high voltage when unplugged?
assume that they do.
measure before touching.
Since you tried another PSU board that was likely okay even if dirty, and you got the exact same symptoms—then i’m gonna say your problem is NOT on the PSU but on one of the other boards.
You didn’t really troubleshoot this problem and determine that the PSU was bad, you just assumed it was bad, based on stuff you read on the websticle. You obviously don’t have the equipment or skills to troubleshoot it, especially without a schematic. This is too dangerous for a novice.
Yeah, I took a chance that it was the psu after what I read and since the clicking sound came from that board, but as the short could be elsewhere, it could be a problem. TV is at my brothers house, so Monday I will put the original psu back and unplug one at a time the other three boards that are plugged into the psu board to see if that isolates the problem possibly to a board and I can go from there. I'll do my best to avoid a big voltage shock as I like my life at the moment!
I plugged in the original psu board and started unplugging each board to test like you said and the psu works again as long as the large board on the left in the pic is unplugged. I could not see any faulty caps or anything though. Is it worth the risk to try and get a replacement board or can I troubleshoot further now that we know something is going on with the left board? Looks like all the plasma screen lines are plugged into that big board, but how would I test to see if the problem is the board or what is connected to it?
Pic below psu is not in, but you can see the big board on the left. PSU will work if I unplug the top wire to it, or
if I unplug the top wire of the right board where the left board plugs into.
Close up of left board
likely one or more shorted igbt’s.
look at the y buffer chips for burns or holes.thats the 2 green boards left of ysus.
if none found its a good risk to buy a ysus.
or you can get a parts kit and rebuild yours.
I would bet it’s the YSUS, had a 50” LG plasma go out like that. It started with very intermittent pop and momentary screen dim, but eventually progressed to a black screen with sound. Bought a “new” YSUS on Ebay, but got a well used one which still worked for another couple of years of heavy use. Just gotta be very careful not to press on the ribbon cables from the buffer boards to the screen when installing the new YSUS board.
KuoH
Thanks for the help again. Had a look yesterday at the y buffer chips and didn't see anything, but tomorrow I'm over there again and will use my trusty flashlight and a magnifying glass and have a another good look just in case. If I set my DMM to continuity, can I a do a test on the y-buffer chips whilst the board is still connected to the tv or would I have to pull it?
Ours was a little different. Just one pop and then the tv shut down and every time we tried to turn it on it would shut off again.
What model TV is it…might be able to find the cold cathode tube on ebay or something
Maybe he thinks plasma is a form of LCD.
It’s really ashamed manufactures stopped producing plasmas. I love my 2014 Panasonic plasma TV. The general public wants cheap TVs though. And 300 for a 50 inch Vs 600 for a plasma killed them. I think there’s one company that still makes a few
Wow. All these negative waves…
Apologies…didn’t mean to come off as rude or condescending
Googling LG plasma turns off comes up with alot of different fixes, maybe this will help
There’s something to be said about the size and weight of LCDs vs plasmas well. My 50” plasma has been in storage ever since I moved over 2 years ago. The original box it was packed back in won’t even fit in my car and requires 2 people to move as well as unbox and setup the TV. When my “temporary” 42” LCD died, rather than haul the plasma out of storage, it was easier to buy a new 55” slim LCD that fit in the car with the box and set it up singlehandedly.
KuoH
I think the point was about understanding more about the topic before offering advice. What you posted was like someone asking to troubleshoot an LED driver and getting a response like Maglights are notorious for burning out bulbs, did you check for a spare bulb in the tail cap. It was not at all related to the technology or problem, but the responses could’ve been less harsh.
KuoH