LG Plasma 50PC1DR- Y-SUS Issues

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

i found how to reproduce the issue. its something about a 'bad ground' ? its how i would call it.. if i take a wire with the subframe out of the chassis and ground the input boards, the lines appear.

as soon and the subframe is connected to the ground of the chassis, lines appear. what does that mean ?

there is no lines when im using the tuner input !!!

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

It's really something that happens when the little sub-frame that holds the input boards gest grounded. really hard to find what's happening for me.

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

I would put it on the Y-buffers because the lines don't appear to move. I could not be certain. Have you changed the buffers? In which case, suspect the control board.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

its really something on that little sub-framethat holds the input boards and the control board. i have the tv all on the side with that frame upside down and i cant reproduce the issue at all

its whenever the sub-frame holding those 2 boards is being grounded at some point at the bottom of the tv it's creating the issue it seems. really strange ?!?!

// before i start pulling my hair, having a break on this issue..

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

here is a video of what it does with the tv upside down :

http://www.youtube.com/watch?v=hJSdggDVpGs

i really cant figure out what causes that. im used to intermittent and bad connection but this one has me stumped.

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Yes, tab bonds like LCD. I can't see your pic??

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

update.. with the tv upside down, when i press with my palms on the bottom (all across the width of the tv..) i get the lines to display on and off. so it's really at the bottom

is there any connection tabs there that could be loose ?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

ok, well i know it's a bad connection but i don't know where !!!!

if the tv is laying on the floor, picture is pretty good.. if i put it back on the stand, which adds pressure somewhere on the screen i get the lines... its constant

its pretty hard to find where there's the bad connection, been messing with it for 2 hours now !!!

i 'think' it's at the bottom of the tv but its very hard to find out :/

[tw2005]

Re: LG Plasma 50PC1DR- Y-SUS Issues

you guys rock !!!

re-seated all of those flat cables (just rubbed them with my finger and put them back in.. and voila, no more lines. the flat cables on the control board..

argh..problem re-appeared after putting back together.. so again its a bad connection somewhere

I'd avoid using fingers and leaving oily residues which may promote corrosion

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

you guys rock !!!

re-seated all of those flat cables (just rubbed them with my finger and put them back in.. and voila, no more lines. the flat cables on the control board..

argh..problem re-appeared after putting back together.. so again its a bad connection somewhere

[tw2005]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Those lines look the same as what I had after re=installing a buffer board. Turned out to be dirty or bad connection. I removed the board and blew the ffc ribbons and connectors out with a can of air. Reseated the ribbons and my problem was fixed.

I'm thinking maybe logic card or main board for that funky picture. I would not play around with the bottom buffers. The picture looks good then goes weird but the briightness looks ok.

I think the panel is being driven correctly.

I think I read somewhere about rubbery heat blocks going off with age behind those logic boards causing faults but I've only worked on the 2 50PX5D.

Bad LVDS connector, bad joints?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

here is what i get with 1 top buffer connected on a hdmi input with no signal (i know half of the screen is off, bottom buffer is missing)

it's blue lines that moves a little bit.. pixels move around

so far i've swapped the ysus, zsus, 2 buffer boards, power supply and it's still doing it

at the bottom of the tv, there's some other buffers there ?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

not the ysus either...

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

its not the buffers, i just swapped them from the good working set.. will continue swapping boards

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

okay, after a few minutes the screen became all purpleish. here is what it looks like

http://www.youtube.com/watch?v=zqggVr__vVI

those are the lines..

then it started going purple

http://www.fusioninformatique.com/temp/purple.JPG

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Buffers, possibly. Care to share a picture?

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Okay. Grrrrr...

I have another issue with one ive fixed here, where it does horizontal lines across the display. ive swapped z-sus and it didn't change anything, voltages are all set according to panel, ive messed with vsetup, vsetdown and that other pot on the ysus but i can't get rid of those lines.

What can cause such lines and how can i fix this ? is it caused by the panel aging, is this something i could fix using the service menu ?

ive tried messing with vs and va as well, it didn't change anything.

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

It's FE, I don't know if they are compatible but if the boards share the same part # they probably are.

[cheebster]

Re: LG Plasma 50PC1DR- Y-SUS Issues

Good morning. I was wondering, while looking for buffer chips, if there was any x-references for the lg buffer chips on 50pc3d buffer boards..

On the lg boards, they are SN755866. Looking around, i thought, i could use a cheap buffer board with similar chips and use the ic's, would be cheaper.

Here is what i've found, a vizio buffer for 9$ with many ic's. the chips look similar, but are the 2 ic models compatible ?

I wasnt able to find exactly what it was, but i can see FC or something on the chips.

Here is the board itself from the vizio :

http://www.ebay.com/itm/271069140173

And here is a better hq picture of it..

http://i.ebayimg.com/t/LG-6871QDH117A-YDRVTP-/00/s/MTA2NlgxNjAw/$T2eC16dHJGkE9no8iPiUBQQ2jRNbmg~~60_57.JPG

It seems to be FC or FE.. Anyone has a clue what they are and if it's the same ic by a different mfg ?

Thanks in advance !!

[tom66]

Re: LG Plasma 50PC1DR- Y-SUS Issues

I think it's a combination of heat and early IPM design that leads to their failure. But I'm not at all sure. Adding a fan might help.