Sony Saga - 55EX720 board replacement fail (long)

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  • thesteve
    Member
    • Jun 2021
    • 27
    • United States

    #1

    Sony Saga - 55EX720 board replacement fail (long)

    Hi. I think I ruined my TV.

    So I’ve had a KDL-55EX720 for a long time. We’ve been through a lot. It was out of commission for a few years after developing a white line down the middle of the screen. I fixed it though at the beginning of the pandemic and have been using it as a standing desk computer monitor / second TV.

    Well a few weeks ago there was a lightening flash while I was watching TV in the kitchen.
    I had three TVs on at the time, all connected (electrically) to the same HDMI output of my cable box.
    The kitchen TV recovered just fine after blinking off. My 65” Sony in the living room shut off along with the 55.” The 65” eventually came back, as did my Denon AV receiver (after unplugging and cycling the power).

    The older 55 inch started acting funny... I forget the exact details, but it eventually would shut down and flash red 7 times.
    I found an abridged service manual and determined that the 7 flashes is for a temperature sensor.
    The flow chart said to replace the B board. I was pretty annoyed at this, since the TV would work fine but shut down after I think 30 seconds. Obviously, the TV was not too hot. Oh, I tried leaving it unglued for 10 hours/ a few days and I tried a factory reset (didn’t work).

    So I found a B board on eBay. The listing was for a 1-884-078-22, but they sent me a 1-884-078-21.
    So I ordered another board. This time I got a 1-884-078-22, but the connector for the LVDS cable was different as well as a power supply connector (CN6002) and the speaker connector.
    My first instinct was to have nothing to do with this board, even though it was identical in every other visible way. Well I decided not to live in fear and so I saw that if I trimmed two tiny square “ears” on both sides of the LVDS cable end, it would fit. Similarly I modified the power supply connector to fit and planned on soldering the 5 wires and calling it a day. I left the audio plug disconnected for the initial test.

    When I turned on the set the entire screen turned white before shutting down and flashing red and orange lights simultaneously. This wasn’t very assuring. Because of the uncertainty of the rigged power connector, I tried a few times, when I probably should have immediately stopped.
    I checked continuity on every connection of that connector (CN6002).
    I know you’re probably thinking the LVDS cable was not right, but since it’s taped down and so perfectly aligned and rigid, I’m confident that it was aligned properly to the board which gets screwed in place exactly. Also I was extremely careful and used magnifying glasses etc.

    I eventually decided to go back and see if my original board was still working. Nope.
    Now with my old “good” board, standby is ok, but after hitting the power button I get an immediate shutdown and a 5x red LED flash sequence. (goes without saying that there’s no white screen anymore)

    I now have the schematic for the KDL-60EX720.
    I thought this schematic would be identical to my 55EX720, but for some reason on the 65EX schematic, it shows CN6001 to be a 10 pin with all 10 pins used and pin 1 12V. On my 55EX, that plug has no wire at pin 1. But the 12V is present, just at pin 2 though. All 3 of the micro fuses are ok.

    Well I think the eBay board I got was shot and took out maybe my TCON board.
    Thoughts?
    Oh, now that I have the proper service manual (at least for the 65EX) I can see that there is a surface mount chip that I could have tried to replace or bypass for the original temp sense issue.
    Too late now.
    Last edited by thesteve; 06-28-2021, 06:20 PM.
  • thesteve
    Member
    • Jun 2021
    • 27
    • United States

    #2
    Re: Sony Saga - 55EX720 board replacement fail (long)

    I shouldn't have added all the extra details.
    Let's just say I had the 7-flash red LED problem and I replaced the B board.

    The old B board worked fine but would eventually shut down with the 7 flashes.
    The replacement eBay board caused the panel to go all white and then shut down with a constant, simultaneous red and orange LED flashing.

    Could this have been due to some mismatch between my TCON/panel and the replacement B board? Or is it more likely that the eBay B board was defective?

    Either way, I'm now at "square -1" because my original "almost good" B board now immediately gives me 5 red LED flashes after pushing the power button twice.
    This also happens with the LVDS cable removed. The 12V on "pin 1" is there but goes away after the power on attempt.

    Comment

    • thesteve
      Member
      • Jun 2021
      • 27
      • United States

      #3
      Re: Sony Saga - 55EX720 board replacement fail (long)

      Holy cow, I can’t believe I got it working again!
      I just did a better search on the 5x LED flash (instead of the dumb flow chart which assumes the customer didn’t Fuss with anything) and came up with: Panel ID NVM Error.
      Well a quick search on that came up with a thread where Sony told some customer that their “BAL board is generic” and something about the firmware and a USB stick.
      Well I thought about this and remembered the factory reset.
      I just did this again (hold “arrow up” on remote and push power button on TV)
      AND IT WORKED! Beautiful good ol’ snow and a green light!

      So now I’m wondering, should I be so bold as to try the eBay board again with another reset? Or should I quit while I’m ahead and take a step back.
      I’ll think more on this, but just wanted to share the good news. (Although so far I’m talking to myself).

      BTW my name is Steve and this is my first post. I put up a brief Bio paragraph in the mandatory first post thing.

      Comment

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