LG Plasma 50PC1DR- Y-SUS Issues

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

In a dark room, any light emission visible from the screen? Do you hear faint buzzing from the sustains?

I don't drink beer but you can buy me cola .

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

i can hear faint buzzing from the sustains, yes. on first time i fired it up, i saw colored dots on the screen, but it stopped after a few on-off cycles, i see nothing on the screen now.

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

No light emission from screen in dark room? It will be quite dim, like a backlight on an LCD.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

nothing at all !can i use the diag leds or status leds on the main board for something ? the pattern they give me probably says something, but i havent seen any reference for them !

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

They just tell you temperature in binary... I think they are not all supposed to be lit (too high otherwise), or something like that...

OK, so you have good Va too? Since you are getting no light emission, that means no PRIMING is happening - this is what Vsc and -Vy are for. It could be the same dodgy IPM loading them down too much?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

um. good question. should i try this ysus board on my good working tv or risks are high of frying something else ?

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

If you change Y sustain and buffers at the same time, I think the risk is small. It will help eliminate a control board or main board fault. Did you check if you can get good sound from a video input?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

i think the issue is on the y-sus again. i will try this ysus on the other working plasma.

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Just be sure to change the buffers at the same time, in case it is those shorted causing the problem. Though I think most LG plasmas will not be damaged by shorted buffers (they will simply shut down) it is worth being cautious.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

oh well, i got 2 problems on this one, ysus is at fault still and lower buffer is faulty. ah well.. that plasma works fine with the lower buffer and the ysus from the working plasma. / that lower buffer suffered from a shorted fet earlier today, swapped it, but might be that one of the buffer chip was also damaged.. im gonna poke around this one.

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

So, you determined the buffer to be the fault on the one you're currently repairing? Is the other one still working after you borrowed its boards?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

the working one, didnt put the boards back. the second one, aint working until i put the good ysus from working on, and also lower buffer.

will find out, but what i now know is that everything else is fine other than those 2.

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

You can always try my "trick" of locating the shorted buffer IC - apply about 12V to the Y buffer input connections (where the Y sus would bolt on), and the bad chip will make itself quite apparent usually with a small (or large!) amount of the magic smoke.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

is polarity important ?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

tom66 for president !

hey hey, that trick works ! 1 chip smoked when i applied 12vdc with a benchtop psu on the bad buffer board. on the good one, nothing happened just 2a power consumption. so it's a bad chip not a bad fet ! i wonder if i should use hot air and try to swap only that chip. not worth it maybe..

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

The chips are something like $3 each so if you know what you are doing it can save you a lot of money in replacement buffers.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

i've got hot air (used to have infrared when i was doing laptops, but aint doing much anymore..)

i guess i could swap one

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

tom66, can you use 12vdc on a good board ? say you doubt one board is good or bad and cant/wanna skip trying it.. is applying 12vdc a good way of checking if one has a short, or that would kill a good buffer ?

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

If the buffer isn't shorted, don't test it, as it will only locate the dead IC.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Alright. Well well, now i have to try to figure out why this y-sustain i have doesn't power on the screen. everything else is fine, i see all good voltages on it just no screen. i will swap j015 since ive already replaced j016, then will put another j016 on it...

i can't even trust the 'new' j016's ive got since they're from china, used..
is there any known compatibility issues with the sanyo chips and the lg ones ? mix and match..

side note : i've found this ;

http://www.dread.cz/web/opravy/plzma-lg-42pc1rr

seems weird, i dont understand what is the guy doing. he's adding some IRFP260N's, but to replace what exactly in the failed ipm ? from the pictures i see burned stuff on the small plates with bonding wires, is that what he's replacing with the IRFP260N's ? how are those little plates called ?