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88-2 SIO board, damaged capacitor, need some help.

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    88-2 SIO board, damaged capacitor, need some help.

    88-2 SIO board, damaged capacitor, need some help.

    Can I just remove the damaged capacitor? If I remove the damaged capacitor, the 88-2 SIO board can still working?????

    The damaged capacitor labeled JM 16V Y5S, what the specification about this capacitor? If I have to replace the capacitor.

    note: the capacitor is mechanically damaged in transition process.

    Thank you.
    Leiy.







    Last edited by leiy; May 21, 2015, 09:49 PM.
    www.worldcommunitygrid.org (World Community Grid: a scientific research projects)
    Altair 8800,1974, one of 1st made, http://www.vintage-computer.net/?p=229
    Altair 8800 rev.0 SN221148A, http://www.vintage-computer.net/?p=202
    Altair 8800 rev.0 SN221876K, http://www.vintage-computer.net/?p=77 most detailed photos
    Here's Altair 8800 rev.0 survivors list for reference: http://www.vintage-computer.net/?p=144

    #2
    That's a plain old 0.1 uF 16V disc ceramic cap. You can either find one to match it (if you care about looks) or just use any old 0.1 uF (or something in that range) to replace it. It's a bypass cap, so the rating isn't super critical. Modern caps for this purpose tend to be ultra-tiny MLCs, so technology marches on.

    I suspect that it would work just fine without the cap, so you don't have to be in a hurry to replace it. Modern caps tend to marked with the code "104" to signify this value.
    Reach me: vcfblackhole _at_ protonmail dot com.

    Comment


      #3
      Some of the others look a bit odd, pretty sure I can see part of the metal disk exposed on a couple of others. If you get intermittent issues it might be worth replacing all of these.
      Dave
      G4UGM

      Looking for Analog Computers, Drum Plotters, and Graphics Terminals.

      Comment


        #4
        Originally posted by Chuck(G) View Post
        That's a plain old 0.1 uF 16V disc ceramic cap. You can either find one to match it (if you care about looks) or just use any old 0.1 uF (or something in that range) to replace it. It's a bypass cap, so the rating isn't super critical. Modern caps for this purpose tend to be ultra-tiny MLCs, so technology marches on.

        I suspect that it would work just fine without the cap, so you don't have to be in a hurry to replace it. Modern caps tend to marked with the code "104" to signify this value.
        Exactly, it is a 100nF ceramic capacitor. It is not critical, but better if you replace it. You can try searching another similar at some ancient board, for example.

        @Chuck(G): I'm new here, I need to ask you a private question. Please, could you send me a message? Thank you!

        Comment


          #5
          If you want to replace them all with disc ceramics (like with like), you can hardly find a cheaper capacitor

          Personally, I'd probably replace them all with monolithic axial-leded ceramics. They just look neater and aren't likely to get damaged.

          Capacitor technology has come a long way in 30 years.
          Reach me: vcfblackhole _at_ protonmail dot com.

          Comment


            #6
            I'll take a look later and see if I have a spare matching capacitor. I have a box of NOS green ones floating around.

            Comment


              #7
              Thanks for all the value helps.

              I'm decide to replace them, when ready.

              after some short circuit checks, I mounted this 88-2 sio board to Altair 8800 computer, no smoke happen, the temperature of VRM is at normal range, seems it will work ok.


              Thanks.
              Leiy.



              Last edited by leiy; May 22, 2015, 10:59 PM.
              www.worldcommunitygrid.org (World Community Grid: a scientific research projects)
              Altair 8800,1974, one of 1st made, http://www.vintage-computer.net/?p=229
              Altair 8800 rev.0 SN221148A, http://www.vintage-computer.net/?p=202
              Altair 8800 rev.0 SN221876K, http://www.vintage-computer.net/?p=77 most detailed photos
              Here's Altair 8800 rev.0 survivors list for reference: http://www.vintage-computer.net/?p=144

              Comment


                #8
                Originally posted by Corey986 View Post
                I'll take a look later and see if I have a spare matching capacitor. I have a box of NOS green ones floating around.
                That's perfect, if the board can replace with original vintage one. Thank you.
                www.worldcommunitygrid.org (World Community Grid: a scientific research projects)
                Altair 8800,1974, one of 1st made, http://www.vintage-computer.net/?p=229
                Altair 8800 rev.0 SN221148A, http://www.vintage-computer.net/?p=202
                Altair 8800 rev.0 SN221876K, http://www.vintage-computer.net/?p=77 most detailed photos
                Here's Altair 8800 rev.0 survivors list for reference: http://www.vintage-computer.net/?p=144

                Comment


                  #9
                  UPDATE

                  Chuck(G) is right, the damaged capacitor is nothing affect the operation of this 88-2-SIO board.

                  I run keyboard echo program(code from tkc8800.com) on front panel, the the 88-2-SIO board function perfectly!!!!!!

                  Keyboard echo program code from tkc8800.com


                  Code:
                          000:    076 003 323 020 076 021 323 020
                          010:    333 020 017 322 010 000 333 021
                          020:    323 021 303 010 000



                  The light status when keyboard echo program are running.





                  Thank you.
                  Leiy
                  Last edited by leiy; May 22, 2015, 11:49 PM.
                  www.worldcommunitygrid.org (World Community Grid: a scientific research projects)
                  Altair 8800,1974, one of 1st made, http://www.vintage-computer.net/?p=229
                  Altair 8800 rev.0 SN221148A, http://www.vintage-computer.net/?p=202
                  Altair 8800 rev.0 SN221876K, http://www.vintage-computer.net/?p=77 most detailed photos
                  Here's Altair 8800 rev.0 survivors list for reference: http://www.vintage-computer.net/?p=144

                  Comment


                    #10
                    As far as the "chipped" disc ceramics go, it's not as bad as it looks. Manufacturers of precision disc ceramics start with a complete device, then saw a notch in them until the capacitance reaches the desired value. I wouldn't worry about some surface damange.
                    Reach me: vcfblackhole _at_ protonmail dot com.

                    Comment


                      #11
                      Ok I checked I don't have exact match to that cap. I have the same brand and size electronically, but the ones I have a physically large in green with the same MFR.

                      Sorry,
                      Cheers,
                      Corey

                      Comment


                        #12
                        I think the 'JM' marking you are referring to is actually '.1M'.

                        According to the 88-2SIO construction manual - these are 0.1 microfarad 10V ceramic disc decoupling capacitors - although your 16V marking implies 16 Volts rather than the parts list in the assembly manual stating 10 Volts.

                        Any 0.1 microfarad 10 Volts (or higher) ceramic disc decoupling capacitor should work just fine.

                        The card will technically work without the decoupling capacitor(s) - but they are there to prevent transients on the power rails due to very brief switching currents induced by the integrated circuits. Good logic design requires one decoupling capacitor per integrated circuit. Over time - the capacitors will become damaged. I would suggest replacing them with modern parts to ensure continued reliable operation.

                        Dave

                        Comment


                          #13
                          Originally posted by Corey986 View Post
                          Ok I checked I don't have exact match to that cap. I have the same brand and size electronically, but the ones I have a physically large in green with the same MFR.

                          Sorry,
                          Cheers,
                          Corey
                          That's all right.

                          Since the 88-2 SIO can working, relife me a lot.

                          Thank you.
                          Leiy.
                          www.worldcommunitygrid.org (World Community Grid: a scientific research projects)
                          Altair 8800,1974, one of 1st made, http://www.vintage-computer.net/?p=229
                          Altair 8800 rev.0 SN221148A, http://www.vintage-computer.net/?p=202
                          Altair 8800 rev.0 SN221876K, http://www.vintage-computer.net/?p=77 most detailed photos
                          Here's Altair 8800 rev.0 survivors list for reference: http://www.vintage-computer.net/?p=144

                          Comment


                            #14
                            Originally posted by daver2 View Post
                            I think the 'JM' marking you are referring to is actually '.1M'.

                            According to the 88-2SIO construction manual - these are 0.1 microfarad 10V ceramic disc decoupling capacitors - although your 16V marking implies 16 Volts rather than the parts list in the assembly manual stating 10 Volts.

                            Any 0.1 microfarad 10 Volts (or higher) ceramic disc decoupling capacitor should work just fine.

                            The card will technically work without the decoupling capacitor(s) - but they are there to prevent transients on the power rails due to very brief switching currents induced by the integrated circuits. Good logic design requires one decoupling capacitor per integrated circuit. Over time - the capacitors will become damaged. I would suggest replacing them with modern parts to ensure continued reliable operation.

                            Dave


                            Thank you for the valuable suggestions.

                            Leiy.
                            www.worldcommunitygrid.org (World Community Grid: a scientific research projects)
                            Altair 8800,1974, one of 1st made, http://www.vintage-computer.net/?p=229
                            Altair 8800 rev.0 SN221148A, http://www.vintage-computer.net/?p=202
                            Altair 8800 rev.0 SN221876K, http://www.vintage-computer.net/?p=77 most detailed photos
                            Here's Altair 8800 rev.0 survivors list for reference: http://www.vintage-computer.net/?p=144

                            Comment

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