LG Plasma 50PC1DR- Y-SUS Issues

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Shorted FET, or buffer board issues, or possibly the IPM (I'm not sure - there's no schematic diagram so I can't tell where the resistors connect to.)

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Okay.. Well, i'm getting somewhere now. Tried to check the buffers, and i got a bad lower buffer on tv #1. Short as a nail

Nothing new on the y-sus though.. I'm wondering, can i install sockets on y-sus and z-sus boards or the little added resistance would cause issues ?

I got so many IPM's out it'd be QUITE handy to be able to troubleshoot them using sockets..

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

You can try using them. It wouldn't be a good idea for a permanent solution though, as plasmas get very hot (especially the IPMs), and sockets have a tendency to expand and make intermittent contact.

Regarding the buffers, you can try to power the buffer off 12V DC or so, the bad buffer chip will smoke, you can then remove that and the TV should fire up, of course with a black bar where the buffer chip is removed, but it will tell you if the Y-sustain is OK and all other boards are OK.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Okay, well i was right about the bad buffer on tv #1. I'm using a buffer from TV2 now on it, now what the tv does is start up, flashes on off and eventually shut down. No loud pop, all i see is the screen flashing from black to white.. trying to fire up and eventually giving up. Still suspecting one of the IPM's, but i don't even know which !

I've seen so much information i don't even know anymore which failed ipm gives this symptom.

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Many TVs now don't like just one buffer removed due to the data being changed from one to another. So it doesn't surprise me that they go a little crazy.

The IPMs only make the picture light up. If you have a lit up picture, they are pretty much guaranteed to be working.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Well i've used a good buffer from tv #2 on the tv #1 !! It's not missing a buffer, but still acting crazy (flashing picture on off, sound ok, then shut down after struggling to fire tv up).

I really wish i was able to figure out if an ipm is good or bad !!!

With that gummy stuff, it's really nearly impossible to tell, i've seen a bad one with the burned little square boards on the ipm... this one was clearly bad

Anyone know a reliable way with a DMM test to know if a IPM is good ?

I'm also wondering, if there's a way to know if a buffer is good other than the meter test on the y-sus connection pads. If a buffer has no shorts, one buffer chip (not a fet, but a buffer chip..) can still be bad, and meter won't tell, no ?

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Do you have a scope, or access to one?

[vinceroger69]

Re: LG Plasma 50PC1DR- Y-SUS Issues

this seems a good training manual

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

I don't have one, but that recycling center i got the plasmas for had one on the shelf there, 10$ and it's mine i guess. Seemed ok.. but i never used one.

I guess i might be able to understand how that thing works.. It'd be handy to really find out what's going on with the ipm's ? i'll grab it later today

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

You will also need a fixed 10X probe, with a 400V minimum rating. $10 would be an absolute bargain for one, are you sure it is in good working order? And no one else will have taken it?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Not a lot of ppl know this place, it's small and fairly recent. I'll drop in later today see if i could pick it up. I'll google the model # before i buy Hey, 10$ is 10$ lol

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Well, for comparison I paid (in GBP converted to USD) $100 for my 20 MHz one, and $400 for my 100 MHz digital one.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

At some point i was looking to buy one that was hackable.. i think it was made by Rigol. I'll look it up again.. Might be a good idea to buy one at this point

edit : http://www.ebay.com/itm/Rigol-Oscill...item3efb96a226

this is exactly the hackable one i was looking to buy. never used a scope before, though

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

I bought some ipm's (yppd-j016's) to try on the boards. I see they are the ER ipm's and these seem to be the hardest working ones and more commonly failed than the J015's sustain ipm's, is that right ?

I also bought a hakko 808 desoldering gun which will make life really easier on the ipm removals. It seems like a great tool for anyone doing even a few reworks with multi pin ic's

[tw2005]

Re: LG Plasma 50PC1DR- Y-SUS Issues

In the photos I see that next to those burnt R100 D35 & D36 are not populated. Is that the case still or are they the diodes you were replacing?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

hi tw2005 ! they are not populated, but i never removed anything from there, i think it's by design that they are missing.

i was also wondering.. that waxy material that seems to be leaking from the orange caps, is that really coming from those caps that are leaking ? i've never seen such caps leak..

I've noticed on 2 of the y-sus boards that waxy stuff from those caps. a lot of it..

Need to replace the whole bank of caps ? Would be a good idea to do so ? So many questions.. well, i hope i'll someday be able to fix those plasmas

[tw2005]

Re: LG Plasma 50PC1DR- Y-SUS Issues

hi tw2005 ! they are not populated, but i never removed anything from there, i think it's by design that they are missing.

i was also wondering.. that waxy material that seems to be leaking from the orange caps, is that really coming from those caps that are leaking ? i've never seen such caps leak..

I've noticed on 2 of the y-sus boards that waxy stuff from those caps. a lot of it..

Need to replace the whole bank of caps ? Would be a good idea to do so ? So many questions.. well, i hope i'll someday be able to fix those plasmas

I'll be damned. I have 2 x 50PX5D sets and one has had a board swap and I have an "A" revision and a "B". You're right, not populated on the "B" rev.

I can't see the waxy stuff. Are you talking about the Polyester caps?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

yes ! those orange caps all in line. is it remotely possible that some of these leak waxy stuff ? of they don't even contain anything similar ?

i have a fluke 115, i'm going to check if im able to check these caps with it... will report back

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

They are just metal and poly insulator, they very rarely fail and when they do, they would be like a short circuit to the power supply, similar to IPM, but I have never seen them fail on LG's.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Ah ! So i can rule that out.. maybe that stuff is just something they've put between some caps to hold them there or something. I just got in with that Hakko 808, will pull out all the ipm's just for the heck of it right now.