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IBM 5153 flickeryness

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    IBM 5153 flickeryness

    Here's a new one.

    The person I bought this from says it works ok then 'overheats' and eventually goes dark. I haven't seen this yet.. although the sudden brightness flashes seem to worsen with time.

    #2
    I lied.. it actually does get worse and the full brightness comes on and stays on and then it starts threatening to black out entirely.

    Comment


      #3
      Something is upsetting the DC conditions for the CRT, when the fault occurred and the screen brightened up, vertical retrace lines were visible.

      For this, like many faults it would be a matter of getting in there with the scope, initially looking at the output of the gun amplifiers and if the defect was there tracing through the circuit back to the input, and looking at the blanking voltages too. Some of the CRT blanking circuitry is very close to the very front edge of the pcb, near the bottom of the CRT bulb and that part of the pcb I have seen cracked if the monitor has been dropped, so carefully inspecting the pcb in that area is also helpful.

      One of the worst things that could happen with a fault like this, is that it could go away before you find it, so disturb as little as possible before making the tests with the scope.

      Comment


        #4
        Let us know what the solution is if you come up with one

        Comment


          #5
          Could be a poor connection/ cold solder joint. Also could be a crack in something creating an arc.

          I would personally first try going over the board and reflowing stuff, especially connectors and sockets. I would also take a good look at the components visually to see if there is anything obviously burned or physically leaking.

          If doing this makes the problem go away, then I don't see the issue with that. Perhaps it would be bad if the fault was a crack in the PCB that temporarily healed itself when you shift the weight of the thing or something like that.

          Comment


            #6
            I was looking up info on the 5153 and came across a post that mentioned needing to 'work the controls' on the monitor if they feel stiff. So I turned each to fullest extent clockwise and counterclockwise. Contrast felt fine but brightness was super stiff. After about 20 full arounds, I powered up.. almost no flickering. Did about 20 more.. none whatsoever. I actually ran out of time waiting for it to go nuts.. it ran in excess of 30 minutes without issue. So maybe that's where my issue is?

            Comment


              #7
              Originally posted by falter View Post
              I was looking up info on the 5153 and came across a post that mentioned needing to 'work the controls' on the monitor if they feel stiff. So I turned each to fullest extent clockwise and counterclockwise. Contrast felt fine but brightness was super stiff. After about 20 full arounds, I powered up.. almost no flickering. Did about 20 more.. none whatsoever. I actually ran out of time waiting for it to go nuts.. it ran in excess of 30 minutes without issue. So maybe that's where my issue is?
              Maybe dirty pots. Could try to clean with CRC is you can find it.

              Surely not everyone was Kung-fu fighting

              Comment


                #8
                Get Caig Deoxit. Spray into the holes on the pots from inside and work the switch back and forth 50 times each way.

                https://caig.com/deoxit-d-series/

                Comment


                  #9
                  Originally posted by Agent Orange View Post

                  Maybe dirty pots. Could try to clean with CRC is you can find it.
                  Yes, the best move is to clean the pots with CRC's CO contact cleaner.

                  But, after that, you ideally cannot leave them dry. Once they are cleaned, the best move is to apply Inox's mx-3, this leaves a very long lasting high purity lubricant that protects from both oxidation on metals and wear from friction and will keep the pot in good order.

                  (My experiments with Caig deoxit and about 4 other products on metals such as brass and copper indicated it was less favorable than MX-3, which won the prize for the better result)

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