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Type: Posts; User: m_thompson

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  1. Replies
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    Testing the completely digital boards like the...

    Testing the completely digital boards like the M7680 and M7681 should be easy. The other boards that are partially analog and partially digital will take some extra effort.

    I wrote Windows...
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    There is a version of Moonlander that runs on the...

    There is a version of Moonlander that runs on the GT40 and uses a light pen for control.
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    Doug, There is a rubber band underneath the...

    Doug,

    There is a rubber band underneath the coiled spring on your hubs. The rubber has turned to rock and won't compress when you try to install or remove a tape reel. You can remove the coiled...
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    211

    The DC power requirements for a TU55 are...

    The DC power requirements for a TU55 are different from a TU56. If the 8/I came with the TU55s then it will already have the correct power supplies.

    At the RICM we have found several TU55 heads...
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    It is for the frame around an 8/a programmer's...

    It is for the frame around an 8/a programmer's panel. Hopefully it is the right color.
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    1,157

    Next Saturday when I am at the RICM I will take...

    Next Saturday when I am at the RICM I will take 'scope images for the transformer pins. I will also measure the resistance for the coils, if that will help.

    During the week I will continue working...
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    I bought a bag of 25 MPS6560 transistors on eBay....

    I bought a bag of 25 MPS6560 transistors on eBay. The bad Q10 from the Bytesaver had reasonable diode drops base-collector and base-emitter, but had a Hfe of 5. The first new transistor that I tested...
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    I am trying to LT SPICE model the Royer...

    I am trying to LT SPICE model the Royer Oscillator, but have not gotten it to resonate yet.

    Using a pulse generator to control Q10 and can adjust the transformer turns ratio to get 30V output from...
  9. Replies
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    This is what our power supply designer through...

    This is what our power supply designer through that the transformer might look like.

    64349
  10. Replies
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    5,016

    I just received some custom made DEC white spray...

    I just received some custom made DEC white spray paint from MyPerfectColor.com to repaint PDP-8/e programmer's panels. $63 for three cans including shipping. I haven't tried it yet.

    Hedrix Fast...
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    1,157

    Our power supply designer guessed at the...

    Our power supply designer guessed at the transformer design. I will try it in LT SPICE to see if it will work, and to determine the turns ratio in the transformer.
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    I sent the schematic to one of our power supply...

    I sent the schematic to one of our power supply designers at work and asked him to guess what is in the transformer.
  13. Replies
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    I would like to use LT SPICE to simulate the 30V...

    I would like to use LT SPICE to simulate the 30V programming supply, but have no idea what is inside of the transformer.
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    The open was where the wire went down the side of...

    The open was where the wire went down the side of the bobbin and made a 90 degree turn to start the winding. I might run the wire down the side and intersect the bobbin at a tangent so there is less...
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    371

    You are right, the summer interns are back in...

    You are right, the summer interns are back in school.
  16. Replies
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    Fixing a PC09

    The PC09 paper tape punch on the RICM's PDP-9 has been broken for about 30 years. The Timing Generator coil that senses the crankshaft rotation is open, so no PUN SYNC signal, so no punching. Because...
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    Broken Cromemco 8k Bytesaver

    We are working on a Cromemco 8k Bytesaver in an Altair 8800 at the Rhode Island Computer Museum. Today we found that the 30V power supply was not working. Using the diode function in a DVM the...
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    At first power up I always reform all of the...

    At first power up I always reform all of the capacitors, even they electrolytics on the flipchips.
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    I gave my Alphas away because they seemed too...

    I gave my Alphas away because they seemed too modern compared to my PDP-8 or PDP-11 systems.

    The RICM has one Alpha machine that would be fun to get running. It is a CRAY T3E-900 that has 36x 450...
  20. Seeks are really noisy. What model disk?

    Seeks are really noisy. What model disk?
  21. Replies
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    It would be helpful if you removed the top front...

    It would be helpful if you removed the top front cover and took a picture of the boards that are installed. Just four screws and the top cover lifts off. No need to remove the boards. The boards...
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    The 11/24 is a nice little Unibus system and...

    The 11/24 is a nice little Unibus system and should have some value to a PDP-11 enthusiast. Pictures of the system and the boards inside would help. We can help you identify the boards in the...
  23. Me too.

    Me too.
  24. Did you check the Mark Track Timing Generator for...

    Did you check the Mark Track Timing Generator for correct timing? Mine was off a little and caused problems when formatting tapes.
  25. My TD8E and TU56 were painful to get working....

    My TD8E and TU56 were painful to get working. Mostly because the TD8E was scrapped by DEC and had never worked.

    I have found some DECtapes that format fine in PDP-8 format, but get various Phase...
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