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Altair Disk Drive power boards

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  • B Degnan
    Hail Mary pass here..(an American phrase for nothing to lose).. Anyone have a Disk Power Supply board for a single 8 disk drive unit for sale? Does not
    Message 1 of 7 , Nov 10, 2013
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      Hail Mary pass here..(an American phrase for nothing to lose)..

      Anyone have a "Disk Power Supply" board for a single 8" disk drive unit for sale?  Does not need to be populated.  Here's a photo of the board I'd like to replace:

      http://vintagecomputer.net/MITS/88-DCDD_rev0/MITS_Drive_1_power-supply-bd.jpg

      There are some heavily scorched spots and improvised components that I'd like to replace.  The board currently blows out the drive's 3Amp fuse after about 20 seconds.  It's too tough to test everything before the fuse blows, and I am afraid I would damage something on the logic board in the process. 
      I'd like to replace all of the expendable parts asit has been many decades since this has been done.

      If no one has one, I will work with what I've got.  The drive and logic board are good at least, I can read disks and boot with these components.

      I have already removed the caps and the improvised voltage regulators.

      Bill
    • alltare
      Bill, Is it an FD4xx drive? The spindle motor (a stepper) may be worn enough that it won t spin, causing an overloaded power supply. Does the fuse blow when
      Message 2 of 7 , Nov 10, 2013
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         Bill,

        Is it an FD4xx drive?  The spindle motor (a stepper) may be worn enough that it won't spin, causing an overloaded power supply.  Does the fuse blow when the drive door is open at powerup (the motor won't be enabled).  Or does it only blow after the drive door is closed?


        steve

        _----------



        ---In altaircomputerclub@yahoogroups.com, <billdeg@...> wrote:

        Hail Mary pass here..(an American phrase for nothing to lose)..

        Anyone have a "Disk Power Supply" board for a single 8" disk drive unit for sale?  Does not need to be populated.  Here's a photo of the board I'd like to replace:

        http://vintagecomputer.net/MITS/88-DCDD_rev0/MITS_Drive_1_power-supply-bd.jpg

        There are some heavily scorched spots and improvised components that I'd like to replace.  The board currently blows out the drive's 3Amp fuse after about 20 seconds.  It's too tough to test everything before the fuse blows, and I am afraid I would damage something on the logic board in the process. 
        I'd like to replace all of the expendable parts asit has been many decades since this has been done.

        If no one has one, I will work with what I've got.  The drive and logic board are good at least, I can read disks and boot with these components.

        I have already removed the caps and the improvised voltage regulators.

        Bill
      • mfeberhard
        Steve is right - a sticky spindle motor will blow the power supply fuses. If the Spindle motor is not spinning freely, you can usually repair them - the
        Message 3 of 7 , Nov 10, 2013
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          Steve is right - a sticky spindle motor will blow the power supply fuses. If the Spindle motor is not spinning freely, you can usually repair them - the problem is usually that the bearings have dried up.


          You can disassemble the motor and pull the bearings. They can either be replaced, or cleaned and re-packed.


          To clean them, remove the slim c-clip that holds the dust cover on both sides of each bearing. Then lift out the dust cover (without deforming it). Then wash the dried-out grease out of the bearing with a decent solvent. Then thoroughly re-pack the bearing with good grease. The reassemble the bearing, and clean the grease from all outside surfaces. Then reassemble the motor, and the drive.


          A bit tedious, but I have done this successfully several times.



          ---In altaircomputerclub@yahoogroups.com, <alltare@...> wrote:

           Bill,

          Is it an FD4xx drive?  The spindle motor (a stepper) may be worn enough that it won't spin, causing an overloaded power supply.  Does the fuse blow when the drive door is open at powerup (the motor won't be enabled).  Or does it only blow after the drive door is closed?


          steve

          _----------



          ---In altaircomputerclub@yahoogroups.com, <billdeg@...> wrote:

          Hail Mary pass here..(an American phrase for nothing to lose)..

          Anyone have a "Disk Power Supply" board for a single 8" disk drive unit for sale?  Does not need to be populated.  Here's a photo of the board I'd like to replace:

          http://vintagecomputer.net/MITS/88-DCDD_rev0/MITS_Drive_1_power-supply-bd.jpg

          There are some heavily scorched spots and improvised components that I'd like to replace.  The board currently blows out the drive's 3Amp fuse after about 20 seconds.  It's too tough to test everything before the fuse blows, and I am afraid I would damage something on the logic board in the process. 
          I'd like to replace all of the expendable parts asit has been many decades since this has been done.

          If no one has one, I will work with what I've got.  The drive and logic board are good at least, I can read disks and boot with these components.

          I have already removed the caps and the improvised voltage regulators.

          Bill
        • B Degnan
          This sounds like a smart thing to do regardless. It could be that the motor is strained, at a minimum contributing to the problem. Bill ... From: eberhard
          Message 4 of 7 , Nov 11, 2013
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            This sounds like a smart thing to do regardless.  It could be that the motor is strained, at a minimum contributing to the problem.
            Bill



            -----Original Message-----
            From: eberhard <eberhard@...>
            To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
            Sent: Mon, Nov 11, 2013 12:50 am
            Subject: [Altair Computer Club] RE: RE: Altair Disk Drive power boards



            Steve is right - a sticky spindle motor will blow the power supply fuses. If the Spindle motor is not spinning freely, you can usually repair them - the problem is usually that the bearings have dried up.

            You can disassemble the motor and pull the bearings. They can either be replaced, or cleaned and re-packed.

            To clean them, remove the slim c-clip that holds the dust cover on both sides of each bearing. Then lift out the dust cover (without deforming it). Then wash the dried-out grease out of the bearing with a decent solvent. Then thoroughly re-pack the bearing with good grease. The reassemble the bearing, and clean the grease from all outside surfaces. Then reassemble the motor, and the drive.

            A bit tedious, but I have done this successfully several times.


            ---In altaircomputerclub@yahoogroups.com, <alltare@...> wrote:

             Bill,
            Is it an FD4xx drive?  The spindle motor (a stepper) may be worn enough that it won't spin, causing an overloaded power supply.   ;Does the fuse blow when the drive door is open at powerup (the motor won't be enabled).  Or does it only blow after the drive door is closed?

            steve
            _----------


            ---In altaircomputerclub@yahoogroups.com, <billdeg@...> wrote:

            Hail Mary pass here..(an American phrase for nothing to lose)..

            Anyone have a "Disk Power Supply" board for a single 8" disk drive unit for sale?  Does not need to be populated.  Here's a photo of the board I'd like to replace:

            http://vintagecomputer.net/MITS/88-DCDD_rev0/MITS_Drive_1_power-supply-bd.jpg

            There are some heavily scorched spots and improvised components that I'd like to replace.  The board currently blows out the drive's 3Amp fuse after about 20 seconds.  It's too tough to test everything before the fuse blows, and I am afraid I would damage something on the logic board in the process. 
            I'd like to replace all of the expendable parts asit has been many decades since this has been done.

            If no one has one, I will work with what I've got.  The drive and logic board are good at least, I can read disks and boot with these components.

            I have already removed the caps and the improvised voltage regulators.

            Bill


          • mfeberhard
            Be prepared - you will probably need to realign the drive after replacing the motor bearings... ... This sounds like a smart thing to do regardless. It could
            Message 5 of 7 , Nov 11, 2013
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              Be prepared - you will probably need to realign the drive after replacing the motor bearings...



              ---In altaircomputerclub@yahoogroups.com, <billdeg@...> wrote:

              This sounds like a smart thing to do regardless.  It could be that the motor is strained, at a minimum contributing to the problem.
              Bill



              -----Original Message-----
              From: eberhard <eberhard@...>
              To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
              Sent: Mon, Nov 11, 2013 12:50 am
              Subject: [Altair Computer Club] RE: RE: Altair Disk Drive power boards



              Steve is right - a sticky spindle motor will blow the power supply fuses. If the Spindle motor is not spinning freely, you can usually repair them - the problem is usually that the bearings have dried up.

              You can disassemble the motor and pull the bearings. They can either be replaced, or cleaned and re-packed.

              To clean them, remove the slim c-clip that holds the dust cover on both sides of each bearing. Then lift out the dust cover (without deforming it). Then wash the dried-out grease out of the bearing with a decent solvent. Then thoroughly re-pack the bearing with good grease. The reassemble the bearing, and clean the grease from all outside surfaces. Then reassemble the motor, and the drive.

              A bit tedious, but I have done this successfully several times.


              ---In altaircomputerclub@yahoogroups.com, <alltare@...> wrote:

               Bill,
              Is it an FD4xx drive?  The spindle motor (a stepper) may be worn enough that it won't spin, causing an overloaded power supply.   ;Does the fuse blow when the drive door is open at powerup (the motor won't be enabled).  Or does it only blow after the drive door is closed?

              steve
              _----------


              ---In altaircomputerclub@yahoogroups.com, <billdeg@...> wrote:

              Hail Mary pass here..(an American phrase for nothing to lose)..

              Anyone have a "Disk Power Supply" board for a single 8" disk drive unit for sale?  Does not need to be populated.  Here's a photo of the board I'd like to replace:

              http://vintagecomputer.net/MITS/88-DCDD_rev0/MITS_Drive_1_power-supply-bd.jpg

              There are some heavily scorched spots and improvised components that I'd like to replace.  The board currently blows out the drive's 3Amp fuse after about 20 seconds.  It's too tough to test everything before the fuse blows, and I am afraid I would damage something on the logic board in the process. 
              I'd like to replace all of the expendable parts asit has been many decades since this has been done.

              If no one has one, I will work with what I've got.  The drive and logic board are good at least, I can read disks and boot with these components.

              I have already removed the caps and the improvised voltage regulators.

              Bill


            • B Degnan
              thanks. I think given that the drive was working fine before it crapped out, I should start with the component replacements on the power board and see how that
              Message 6 of 7 , Nov 11, 2013
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                thanks. I think given that the drive was working fine before it crapped out, I should start with the component replacements on the power board and see how that goes under controlled circumstances
                bd



                -----Original Message-----
                From: eberhard <eberhard@...>
                To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                Sent: Mon, Nov 11, 2013 10:53 am
                Subject: [Altair Computer Club] RE: Altair Disk Drive power boards



                Be prepared - you will probably need to realign the drive after replacing the motor bearings...


                ---In altaircomputerclub@yahoogroups.com, <billdeg@...> wrote:

                This sounds like a smart thing to do regardless.  It could be that the motor is strained, at a minimum contributing to the problem.
                Bill



                -----Original Message-----
                From: eberhard <eberhard@...>
                To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
                Sent: Mon, Nov 11, 2013 12:50 am
                Subject: [Altair Computer Club] RE: RE: Altair Disk Drive power boards



                Steve is right - a sticky spindle motor will blow the power supply fuses. If the Spindle motor is not spinning freely, you can usually repair them - the problem is usually that the bearings have dried up.

                You can disassemble the motor and pull the bearings. They can either be replaced, or cleaned and re-packed.

                To clean them, remove the slim c-clip that holds the dust cover on both sides of each bearing. Then lift out the dust cover (without deforming it). Then wash the dried-out grease out of the bearing with a decent solvent. Then thoroughly re-pack the bearing with good grease. The reassemble the bearing, and clean the grease from all outside surfaces. Then reassemble the motor, and the drive.

                A bit tedious, but I have done this successfully several times.


                ---In altaircomputerclub@yahoogroups.com, <alltare@...> wrote:

                 Bill,
                Is it an FD4xx drive?  The spindle motor (a stepper) may be worn enough that it won't spin, causing an overloaded power supply.   ;Does the fuse blow when the drive door is open at powerup (the motor won't be enabled).  Or does it only blow after the drive door is closed?

                steve
                _----------


                ---In altaircomputerclub@yahoogroups.com, <billdeg@...> wrote:

                Hail Mary pass here..(an American phrase for nothing to lose)..

                Anyone have a "Disk Power Supply" board for a single 8" disk drive unit for sale?  Does not need to be populated.  Here's a photo of the board I'd like to replace:

                http://vintagecomputer.net/MITS/88-DCDD_rev0/MITS_Drive_1_power-supply-bd.jpg

                There are some heavily scorched spots and improvised components that I'd like to replace.  The board currently blows out the drive's 3Amp fuse after about 20 seconds.  It's too tough to test everything before the fuse blows, and I am afraid I would damage something on the logic board in the process. 
                I'd like to replace all of the expendable parts asit has been many decades since this has been done.

                If no one has one, I will work with what I've got.  The drive and logic board are good at least, I can read disks and boot with these components.

                I have already removed the caps and the improvised voltage regulators.

                Bill




              • alltare
                Hmmm... Those black bullet-shaped capacitors on the drive s PC board were not very reliable. Check them for shorts or leakage. Steve ..........
                Message 7 of 7 , Nov 11, 2013
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                  Hmmm... Those black bullet-shaped capacitors on the drive's PC board were not very reliable. Check them for shorts or leakage.Steve ..........
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