Lg 42pj350
hello again, my tv is not working properly anymore. I changed bad YSUS board, tv works for 3 days normaly, then it sudenly shows white stripe on the bottom of the screen, first bigger one then smaller, shows OSD for few seconds and restarts. See video https://app.box.com/s/p99duuc60f5m8gv36nw9 (sorry for bad quality). Any help?
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I have an LG plasma that after reading through a bunch of posts and doing some testing I believe has a bad YSUS board. The problem is that that doesn't make sense to me for some of the symptoms. The problem started yesterday. While watching a movie the TV just shut down like I pressed power. I have it hooked to a PC and use RS232 to turn it off and on so I thought maybe something had glitched there. I turned it back on and finished the movie with no problems. The same thing happened today so I checked logs to see if something in the control glitched and sent an off command but it didn't, After... -
Problem
This is an LG edge LED lit LCD Display. The LEDs are on the bottom edge of the display. There are 2 bars (left and right) Each bar has many LEDs and a 6 pin connector. Each pin drive several LEDs thus is the highest current flow / heat junction. The weak lead free solder gradually fails with thermal expansion/contraction cycling and increases resistance. PSU will compensate up to a point, then when the current is too high, PSU just shut down the backlight causing a dark display. I have even seen one which the connector just fell off as solder points became completely detached.... -
All left and right refers to looking from rear of TV (or looking from front with TV upside down)
- TV came with vertical bars and no image. Found faulty TVS on left buffer board. Also replaced T-Con (may have damaged the original while hot air removing components, board has slight warp) and have full image but few horizontal lines on the screen. Some of the lines appears to be 2 pixel tall while others are 1 pixel tall.
- Disconnecting left and right buffer board potentially reveals problems on both sides with different signals (unless this T-Con require jumper like Samsung FB_TRDY1&3) Fault
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LG42PC3D -UD originally with green lamp but no display or audio.
Owner says was working, then went 'pop'.
All 5V caps bulging. replaced.
All PSU output voltages within spec but -Vy is low on YSUS.
One of three parallel fets between SUS_OUT and SUS_DN is zenering,
eventually shorts DG. Replaced all 3 - -Vy now OK.
Y scan buffer test point does not follow YSUS output below -50V
Note: This unit seems to expect YSUS output to park at -Vy in between
drive signal pattern periods. A replacement drive signal board confirms this....11-18-2021, 11:49 AM -
Hi all,
I'm interested in understanding how a buffer board chip is working. I know there's about 90 outputs per chip to the plasma panel, but I'm more interested to know about the input pins. I guess that some of them are address pins, but I want to know more.
So far I've found nothing at all. I haven't found any datasheet about the various buffer chips, and I haven't found any schematic for the buffer board using them (Y Buffer Board in Samsung's terminology).
Any information will make me happy. It can be from any buffer chip or plasma TV manufacturer....
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