I repaired a LG 50" plasma 50pk540 with an intermittent shutdown. Turned out to be cracked solder joint on a transformer on the power supply. I touched up all the major solder joints on the x and y mains while I had it apart. I pluged it in and it fires right up and never shut down( ran for 9hrs). I put the stand on it and pressed the menu button and saw 2 one pixle wide lines about 1" apart, just left of the center of the set. I tried to clean and reset the ribbon on the control board and the one that goes to the screen from the XC center buffer. No luck. I then disconnected. That ribbon again and turned it on and of course that segmet was off, but looked like a maldischarge, and I could still see faint lines. Maybe it is screen burn in, in reverse???? Gonna try a 10 dollar XC buffer. Oh, the lines dont show up on full white screen and they show on most of the test patterens. I will keep you posted.........
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Re: 50pk540
Bad panel. -
Re: 50pk540
Today I got a 50Pk750 with a bad mainboard for free. It has the same panel as the 50pk540 I have with the bad panel. I swapped the mainboard, ldvs cable(to short), and the ir cable. The tv works just fine. Only thing left to do is clamp both tv backs together and drill new screw holes, as only 4 match up now.Comment
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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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- Prior owner tried a replacement main board. No difference.
- Samsung 2x red blinking standby LED = panel fault
- Jumpered FB_TRDY_1 (pin 1 CN1300 left. main tcon->left side buffer boards) and FB_TRDY_3 (pin 95 CN1301 right. main tcon->right side buffer boards) This allows testing individual T-Con (on main board) connection to panel on this Samsung. Found fault on left side (viewing from rear of TV)
- Each side has 2 buffer boards, disconnected left side flex between 2 buffer boards. Fault is on the left most board.
- Tape masking eventually isolated to CN1300 pin 15 (CKV4_GOA) Display
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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.... -
Hello, I have a screen in where sometimes when I open it pop-up vertical multicolor lines (I would say the most of them are green). If I tun off and turn on the screen the lines dissapear or if I leave open the screen after approximately five minutes the lines gone. I measured the below voltages on the main PCB and on the T-CON board and the voltages are the same when it doesn’t display the vertical lines and when it displays the vertical lines. Also, I cleaned all the connectors very good with IPA. I moved back and forth the connectors and the COF tabs but the vertical lines didn't displayed... -
Hi, I'm new around here and hoping that there may still be some people on here that are knowledgable about plasma display repair, as some of the old badcaps forum posts have been pretty useful to me so far.
For any regular plasma TV I probably wouldn't bother to go through this effort, but I have a pro-grade Pioneer plasma which I really want to use and it would be a shame to throw it out since there's not many of them still around these days. The plasma has the typical black horizontal lines that seem plague plasma displays. I've counted 3 lines on top of the screen and 4 at the...
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