Testing & Repairing a Y-Buffer board

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • titan2782
    New Member
    • Dec 2012
    • 2
    • USA
    #1

    Testing & Repairing a Y-Buffer board

    I know that the upper and lower Y-Buffer boards have something wrong with them. When they are plugged in I get a D12V error code. When I leave them off, there is no error.

    What exactly goes bad, the surface mounted ICs? How do I test these boards (other than plugging them in)? Do I need to replace the ICs to repair the board? That's an obvious, kind of dumb question but I have to ask.

    I'm not to keen on soldering surface mount IC's with 60 pins but I also don't want to sped $150 on new boards.

    The boards are

    LJ41-02760A (upper)
    LJ41-02761A (lower)

    The TV is a Sanyo DP42746.

    I've already replaced the bad caps on the main power board and the Y-SUS.

    I've been through this thread https://www.badcaps.net/forum/showthread.php?t=18707 and it was helpful including the links.
    Tags: None
    • Mt.Man
      Senior Member
      • Jun 2012
      • 53
      • USA
      #2
      Re: Testing & Repairing a Y-Buffer board

      Look over each IC closely if they don't have heat sinks attached. Lots of times in the center of the IC on the bad one you might see a hole or burnt mark.

        Comment

        Previous template Next

        Related Topics

        Collapse
        • Tynan Dill
          Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?
          by Tynan Dill
          I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.

          Upon bringing it home and plugging it up, it showed a standby light.

          I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.

          The screen seems to blackout and stay black, but with a flashlight I can see the display.

          With my Playstation 4 connected via HDMI, and running a game I can hear sound.

          Assuming...
          ORIGINAL POWER SUPPLY BOARD
          7 Photos
          11-22-2024, 01:46 PM
        • m1ch43lzm
          HP Pavilion 15-eh Board DAG7HAMB8F0 - CPU throttling to 0.4GHz (PROCHOT_EXT) and black screen
          by m1ch43lzm
          Hi, this is my personal laptop, which the original board (lets call it Board A) blew up PU8700 (TPS51486), making a hole on the board, i had left the laptop at my desk one day with the battery fully charged and didn't touch it for a week, but when i tried to turn it on it didn't
          Thought the battery was dead, so i plugged in the charger then tried to power on, the power LED blinked once, charged LED still orange, unplugged the charger, plugged in again and I noticed the "magic smoke" smell, so i unplugged the charger, removed the back cover and saw the blown IC (the "magic...
          05-12-2025, 08:37 PM
        • howardc64
          TCL 55S425 few horizontal lines, potential failure on both side of panel/buffer board
          by howardc64
          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
          ...
          07-24-2025, 05:17 PM
        • repair-it
          Need advice testing a samsung power supply board with scope
          by repair-it
          I am attempting to test a samsung power supply board to verify the pfc ic is working. I am powering up the board with my isolation transformer. The board turns on fine but when I attempt to connect the ground for the scope probe, it trips out the isolator. I was taught not to 'float my scope' so I am wondering if I should test without connecting the ground lead or would that be asking for trouble? Not sure how else to test, I don't have a portable scope. I could plug direct to mains power but that would bypass the safety factor.
          07-12-2025, 11:00 AM
        • howardc64
          A1312 (27” iMac 2009-2011) A1407 (Thunderbolt Display) A1316 (Cinema Display) Display Black Screen Repair
          by howardc64
          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....
          08-04-2024, 10:36 PM
        • Loading...
        • No more items.
        Working...