D48-D0 flickering/flashing at a very constant rate

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  • bscottjohnston
    Senior Member
    • Aug 2023
    • 52
    • USA
    #1

    D48-D0 flickering/flashing at a very constant rate

    I have a D48-D0 that works on all counts except the backlights flash at a constant frequency of about 3-4 times a second. I used the Voltage measurements as seen in this thread (https://www.badcaps.net/forum/troubl...ure-new-boards) to compare mine.

    With CN301 unplugged with set on I have about 90VDC
    With CN301 plugged in of course the V varies based on the flickering

    These pins have 1.86 VDC not the 3.3 as shown here:
    CN201: PWM5: Pin 14: 3.3VDC
    CN201: PWM4: Pin 13: 3.3VDC
    CN201: PWM3: Pin 12: 3.3VDC
    CN201: PWM2: Pin 11: 3.3VDC
    CN201: PWM1: Pin 10: 3.3VDC

    I took each of the high V leads out of CN301 one at a time and the flickering never stopped. I think the problem is likely on the power supply. Another indication is a slight burn mark on the corner of the board. When I turn the board over I find what looks like Q303. I haven't done a lot of board level work since I was in the Navy 30 years ago. Can anyone tell me what Q303 is? I can't find the schematic for this PS online anywhere for a reference. Any pro's in here who have fixed this before?

    These power supplies are $16 plus shipping on Shop Jimmy. Just shotgun the PS?
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    Tags: None
    • nomoresonys
      Badcaps Legend
      • Jan 2013
      • 12123
      • U.S.
      #2
      If you have to have parts shipped to you, then may as well just get a whole replacement board, see if that one is a match for you: https://www.ebay.com/itm/38460069767...Bk9SR-zboviJYw

        Comment

        • bscottjohnston
          Senior Member
          • Aug 2023
          • 52
          • USA
          #3
          This is the one! Thanks nomoresony

            Comment

            • nomoresonys
              Badcaps Legend
              • Jan 2013
              • 12123
              • U.S.
              #4
              Glad to help.

                Comment

                • bscottjohnston
                  Senior Member
                  • Aug 2023
                  • 52
                  • USA
                  #5
                  Got new part - did nothing to change the problem. I hate throwing money at this stuff. I could do the main board next but with my luck it will be fine too. I've seen "fixes" on YouTube for this before that suggest settings are going to do the trick. I am very leery of that kind of "repair"

                    Comment

                    • nomoresonys
                      Badcaps Legend
                      • Jan 2013
                      • 12123
                      • U.S.
                      #6
                      With the new board, what voltages do you get on CN201, pins 7 and 8, if you can check them in standby, and when you hit power button, what are the voltages and do they change/toggle when you go from standby to power up? and make sure all your connectors are in place.

                        Comment

                        • bscottjohnston
                          Senior Member
                          • Aug 2023
                          • 52
                          • USA
                          #7
                          Pins 7&8 are zero Volts at off/standby

                          Pin 7 = 3.25 VDC on
                          Pin 8 = 3.3 VDC on

                          Checking all the connectors here in a few after this next meeting

                            Comment

                            • nomoresonys
                              Badcaps Legend
                              • Jan 2013
                              • 12123
                              • U.S.
                              #8
                              Originally posted by bscottjohnston
                              Pins 7&8 are zero Volts at off/standby

                              Pin 7 = 3.25 VDC on
                              Pin 8 = 3.3 VDC on

                              Checking all the connectors here in a few after this next meeting
                              Ok, that is good.

                                Comment

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