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Allen 705D Power Distribution

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  • Allen 705D Power Distribution

    After several years of enjoying 2 of the three systems on my rescued 705D working... I am again troubleshooting the 3rd computer... which is the B computer. I believe I missed something when I originally tried to get it working. Examining the plug that goes to the motherboard.. I found that some of the wirewrap terminals have been soldered... certainly not by me. The B computer swaped into the A slot works perfectly. I know there are other boards... but here is my question. I looks like the "power" wires are colored... and the "data" wires are white. Does anyone have experience with power distribution on these three computer instruments? And if I need to replace and rewrap the plug... who manufactured the plugs.
    Cheers
    WichitaTech (Marc-Paul)
    *Allen 705-D * Rodgers 605 * Gulbransen 380-X*

  • #2
    Look at the connections on the power supply to determine what color wires are used for the various voltages, and then use a meter at the edge connector to confirm.

    When I was designing my drop-in replacement for the DM capture board a half dozen years ago, I tried to find some of those PCB edge connectors to set up a testing jig. Suffice to say, although they may be out there, they're hard to find and expensive. I never did find the 70 pin connector I needed. This type of connector used to be ubiquitous, but is rarely, if ever, used today, and I found that the gold plated fingers that these connectors mated with are a specialty item that many PCB fabricators no longer offer.
    -Admin

    Allen 965
    Zuma Group Midi Keyboard Encoder
    Zuma Group DM Midi Stop Controller
    Hauptwerk 4.2

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    • #3
      Thanks... that's pretty much what I thought about the connectors. I couldn't find anything wrong with the supply voltages... so I did something that I would do on analog instruments. I hooked up the audio to the "dead" B computer and wiggled things. I think I either broke a resistive bridge or broke a bridged solder joint on the plug... because I am happy to report it is all working... all three computers and audio. Needless to say I am thrilled. I have one of your midi boards which has worked flawlessly since I installed it. Talk about fun... a working 705 and Hauptwerk/jOrgan etc.
      Cheers
      *Allen 705-D * Rodgers 605 * Gulbransen 380-X*

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