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    #1

    Samsung 225MW EEPROM bootloop

    Hi all,
    I got an old Samsung 225MW TV with BN41-00825 motherboard.
    Since the TV has a buzzer when it starts it makes a beep. The main problem is that the TV goes in a sort of bootloop and beeps every 2-3 seconds.
    So I attached the VGA UART cable and read the debug data using a RT809H programmer:
    <* Mst-VdDec *>: 3
    Power-On[*SCART*]
    <* Mst-VdDec *>: 3
    Power-On[*SCART*]
    <* Mst-VdDec *>: 3
    Power-On[*SCART*]
    <* Mst-VdDec *>: 3
    Power-On[*SCART*]
    <* Mst-VdDec *>: 3
    Power-On[*SCART*]
    <* Mst-VdDec *>: 3
    Power-On[*SCART*]
    <* Mst-VdDec *>: 3
    Power-On[*SCART*]
    According to the Service Manual all the voltages looks good, so I made a backup of the internal flash and all the EEPROMs (1 Settings + 3 EDID) and cleaned the EEPROM.
    Now the TV boots but it's stuck on VGA. If I try to change the source it goes to TV, restarts (beep) and returns to VGA.

    <* Mst-VdDec *>: 3
    Init Pannel Data, Please Wait
    Init EEPROM, Please Wait
    Not Defined Source.
    Not Defined Source.
    Not Defined Source.
    Not Defined Source.
    Not Defined Source.
    Not Defined Source.
    Not Defined Source.
    Not Defined Source.
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    Power-On[*VGA*]
    [*TV*]
    <* Mst-VdDec *>: 3
    Power-On[*VGA*]
    [*TV*]
    <* Mst-VdDec *>: 3
    Power-On[*VGA*]
    I replaced the EEPROM and retried again and it's all the same.
    I removed the Tuner and tried again but pretty same stuff (with only the addition that the board can't communicate with the tuner via i2c).
    I've also tried with another flash dump but same stuff.

    Power-On
    I2C Tuner Error[2-3]-1

    I2C Tuner Error[2-4]-1

    I2C Tuner Error[2-3]-2

    I2C Tuner Error[2-4]-2

    I2C Tuner Error[2-3]-3

    I2C Tuner Error[2-4]-3

    I2C Tuner Error Time Over
    Not Defined Reset I2C Case
    I2C Tuner Error[1]
    I2C Tuner Error[1]
    I2C Tuner Error[1]
    I2C Tuner Error Time Over
    Not Defined Reset I2C Case[*VGA*]
    [*TV*]
    <* Mst-VdDec *>: 3
    Power-On
    I2C Tuner Error[2-3]-1

    I2C Tuner Error[2-4]-1

    I2C Tuner Error[2-3]-2

    I2C Tuner Error[2-4]-2

    I2C Tuner Error[2-3]-3

    I2C Tuner Error[2-4]-3

    I2C Tuner Error Time Over
    Not Defined Reset I2C Case
    I2C Tuner Error[1]
    I2C Tuner Error[1]
    I2C Tuner Error[1]
    I2C Tuner Error Time Over
    Not Defined Reset I2C Case[*VGA*]
    [*TV*]
    <* Mst-VdDec *>: 3
    Power-On
    I2C Tuner Error[2-3]-1

    I2C Tuner Error[2-4]-1

    I2C Tuner Error[2-3]-2

    I2C Tuner Error[2-4]-2

    I2C Tuner Error[2-3]-3

    I2C Tuner Error[2-4]-3

    I2C Tuner Error Time Over
    Not Defined Reset I2C Case
    I2C Tuner Error[1]
    I2C Tuner Error[1]
    I2C Tuner Error[1]
    I2C Tuner Error Time Over
    Not Defined Reset I2C Case[*VGA*]
    I also opened the tuner box to check around and the demodulator "TDA9886TS" heats up a bit even if it's not in use and the entire box absorb around 120mA when powered.

    Unfortunately theres nothing useful in the service menu and most of stuff is made via WinDDC that I don't have (neither the Samsung Jig to connect to).

    Before trying to replace the Tuner module do someone have any suggestion?

    Thank you.
    Attached Files
    Tags: None
  • Answer selected by Jacksoft at 02-16-2025, 07:03 AM.
    Check and replace these electrolytes (a common problem with them, high ripple at 3.3v, 1.8v).
    Attached Files
    • Selected Answer

    Comment

      #2
      Check and replace these electrolytes (a common problem with them, high ripple at 3.3v, 1.8v).
      Attached Files
      • Selected Answer

      Comment

        #3
        Originally posted by lotas View Post
        Check and replace these electrolytes (a common problem with them, high ripple at 3.3v, 1.8v).
        Damn! I totally forgot about ripple! I was fooled by the fact that voltages looked good on every line!
        In fact about two caps where 10 to 14Ohm in ESR test!

        I've replaced all of them you signed in red, thank you!

        By the way the TV shows another problem now (dunno if it was present before because the TV was off by some years).
        About every tested input (Analog TV (just white noise), AV, SCART, HDMI) shows bad glitches excepts for the OSD and the VGA input that works perfectly.
        In first place I thought it was the PI3HDMI412FTBE switch IC but it shows on tv cvbs, composite and RGB scarts too it's strange because they are connected directly into CPU...
        What could be?
        Attached Files

        Comment

          #4
          Check all other electrolytes, the model is old, the electrolytes are not of high quality...

          Comment

            #5
            Yeah, I suspected this. Tomorrow I'll give a look and let you know.
            Thank you so much for now!

            Comment

              #6
              Replaced most of all other caps (expecially all the 100uF 16V that had almost all high ESR) and now it works. Replaced also some others around the amplifier because no audio issue too.
              This board is really crap.

              Thank you for the tips!

              Comment

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