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Re: [Altair Computer Club] 8800b Power Supply

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  • John Crane
    ... From: W Tom Subject: [Altair Computer Club] 8800b Power Supply To: altaircomputerclub@yahoogroups.com Date: Monday, May 10, 2010,
    Message 1 of 7 , May 10, 2010
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      --- On Mon, 5/10/10, W Tom <yahoo@...> wrote:

      From: W Tom <yahoo@...>
      Subject: [Altair Computer Club] 8800b Power Supply
      To: altaircomputerclub@yahoogroups.com
      Date: Monday, May 10, 2010, 3:01 AM

      Does anyone have any comments on Altair power supplies? My comment is that a 17lb transformer can damage an Altair case during shipping, so pack the transformer corner of the box carefully. Use extra packing and cardboard. Make sure the case top is screwed on tight.

      Tom

      Very true about shipping.  I have an 8800B with a very slight bend in the rear panel due to the massive transformer shifting during shipping.  Some people just don't understand inertia.  They pack the exterior extremely well so that there will be no scratches, but forget completely about the interior.  Soft packing material just won't cut it in this suituation.  You need to internally brace it with wood blocks, at least.  Or remove it.  Or use a decent specialist shipping company and use g-force tags on the package to monitor impacts in case you need to prove anything later.  UPS seems to be the worst shipper for delicate items.  However, I've had good results with Navistar.   They basically arrive on site and  build a custom pallet & crate for the item. And they handle things gently.
      So as not to appear anti-Altair; I'll also tell you I received an IMSAI from someone who shipped the unit to me with all the cards installed!  When it arrived,  about half the cards had jarred loose and were rattling around in the card cage.  One disc capacitor was torn loose.  But after the repair, everything worked fine.  I couldn't believe it worked either! 
       
      -J
       
       

    • Jack Rubin
      It sure makes sense to use modern switching supplies for your bench/test units where functionality rather than originality is the key issue. Don t risk your
      Message 2 of 7 , May 10, 2010
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        Message
        It sure makes sense to use modern switching supplies for your bench/test units where functionality rather than originality is the key issue. Don't risk your boards on flaky power supplies!
         
        Jack
         
        -----Original Message-----
        From: altaircomputerclub@yahoogroups.com [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of John Crane
        Sent: Monday, May 10, 2010 10:23 PM
        To: altaircomputerclub@yahoogroups.com
        Subject: Re: [Altair Computer Club] 8800b Power Supply

         



        --- On Mon, 5/10/10, W Tom <yahoo@loslunasnm. net> wrote:

        From: W Tom <yahoo@loslunasnm. net>
        Subject: [Altair Computer Club] 8800b Power Supply
        To: altaircomputerclub@ yahoogroups. com
        Date: Monday, May 10, 2010, 3:01 AM

        Does anyone have any comments on Altair power supplies? My comment is that a 17lb transformer can damage an Altair case during shipping, so pack the transformer corner of the box carefully. Use extra packing and cardboard. Make sure the case top is screwed on tight.

        Tom

        Very true about shipping.  I have an 8800B with a very slight bend in the rear panel due to the massive transformer shifting during shipping.  Some people just don't understand inertia.  They pack the exterior extremely well so that there will be no scratches, but forget completely about the interior.  Soft packing material just won't cut it in this suituation.  You need to internally brace it with wood blocks, at least.  Or remove it.  Or use a decent specialist shipping company and use g-force tags on the package to monitor impacts in case you need to prove anything later.  UPS seems to be the worst shipper for delicate items.  However, I've had good results with Navistar.   They basically arrive on site and  build a custom pallet & crate for the item. And they handle things gently.
        So as not to appear anti-Altair; I'll also tell you I received an IMSAI from someone who shipped the unit to me with all the cards installed!  When it arrived,  about half the cards had jarred loose and were rattling around in the card cage.  One disc capacitor was torn loose.  But after the repair, everything worked fine.  I couldn't believe it worked either! 
         
        -J
         
         

        No virus found in this incoming message.
        Checked by AVG - www.avg.com
        Version: 9.0.819 / Virus Database: 271.1.1/2866 - Release Date: 05/10/10 13:26:00

      • W Tom
        Jack, You give very good advice. What is the approximate cost of switching power supplies for S-100? Are they hard to find? Power is my #1 problem for 8800b
        Message 3 of 7 , Jun 5, 2010
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          Jack,

          You give very good advice. What is the approximate cost of switching power supplies for S-100? Are they hard to find?

          Power is my #1 problem for 8800b mainframes and 88-DCDD drive cabinets.

          The 8800b regulator board is a little hard to get to and replace. The card guides get in the way. That is more of a problem with an 18-slot motherboard than a 10-slot motherboard.

          The BR1 rectifier for 8V is on the back panel. It is hard to reach under the transformer taps. BR2 on the schematic was labeled BR1 on the regulator board. I also found the heat sink loose with dried out grease.

          I have one mainframe with the 18V supply measuring low. I assume that is Q2, a TIP 140. Another mainframe measures high with 23V and -24V. Does that mean Q1 & Q2 are both bad or is it more likely the rectifier?

          Q1 is a TIP 145 on the schematic and may be a TIP 146 or TIP 147 on the regulator board. Q2 may be a TIP 140 or TIP 141. What is the preferred parts for replacement?

          Where can I buy these power transistors and the rectifiers? Can someone suggest a good internet source?

          Tom






















          --- In altaircomputerclub@yahoogroups.com, "Jack Rubin" <jack.rubin@...> wrote:
          >
          > It sure makes sense to use modern switching supplies for your bench/test
          > units where functionality rather than originality is the key issue. Don't
          > risk your boards on flaky power supplies!
          >
          > Jack
          >
          >
          > -----Original Message-----
          > From: altaircomputerclub@yahoogroups.com
          > [mailto:altaircomputerclub@yahoogroups.com] On Behalf Of John Crane
          > Sent: Monday, May 10, 2010 10:23 PM
          > To: altaircomputerclub@yahoogroups.com
          > Subject: Re: [Altair Computer Club] 8800b Power Supply
          >
          >
          >
          >
          >
          >
          >
          >
          > --- On Mon, 5/10/10, W Tom <yahoo@...> wrote:
          >
          >
          >
          >
          > From: W Tom <yahoo@...>
          > Subject: [Altair Computer Club] 8800b Power Supply
          > To: altaircomputerclub@yahoogroups.com
          > Date: Monday, May 10, 2010, 3:01 AM
          >
          >
          > Does anyone have any comments on Altair power supplies? My comment is that a
          > 17lb transformer can damage an Altair case during shipping, so pack the
          > transformer corner of the box carefully. Use extra packing and cardboard.
          > Make sure the case top is screwed on tight.
          >
          > Tom
          >
          > Very true about shipping. I have an 8800B with a very slight bend in the
          > rear panel due to the massive transformer shifting during shipping. Some
          > people just don't understand inertia. They pack the exterior extremely well
          > so that there will be no scratches, but forget completely about the
          > interior. Soft packing material just won't cut it in this suituation. You
          > need to internally brace it with wood blocks, at least. Or remove it. Or
          > use a decent specialist shipping company and use g-force tags on the package
          > to monitor impacts in case you need to prove anything later. UPS seems to
          > be the worst shipper for delicate items. However, I've had good results
          > with Navistar. They basically arrive on site and build a custom pallet &
          > crate for the item. And they handle things gently.
          > So as not to appear anti-Altair; I'll also tell you I received an IMSAI from
          > someone who shipped the unit to me with all the cards installed! When it
          > arrived, about half the cards had jarred loose and were rattling around in
          > the card cage. One disc capacitor was torn loose. But after the repair,
          > everything worked fine. I couldn't believe it worked either!
          >
          > -J
          >
          >
          >
          >
          >
          >
          > No virus found in this incoming message.
          > Checked by AVG - www.avg.com
          > Version: 9.0.819 / Virus Database: 271.1.1/2866 - Release Date: 05/10/10
          > 13:26:00
          >
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