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Thread: PDP11/23-AH type of Power Supply?

  1. #1
    Join Date
    Apr 2014
    Location
    Dordrecht , Netherlands
    Posts
    169

    Default PDP11/23-AH type of Power Supply?

    Today the PDP11/23-AH broke down. BA11
    Just power "OK"Light and than nothing at all.
    With minor base setup and strapped ODT- dead as can be.

    Measuring at the power supply and the "-12V" is very low "-6,8V"
    (of course all cards pulled)
    +5V and +12V are OK.
    It is a switching power supply from 1980 according time stamps components.

    Should be a H780 but it is not.
    The -12V is from a little card and 2x LM339, also 2x 555 timer on board.
    Those timers have a clock pulls at pin 3.

    Any one recognize the type?
    Can not find any where in a schematic the right type.

    PDP1123-AH_Power Supply-002.jpg

    PDP1123-AH_Power Supplu-001.jpg

  2. #2
    Join Date
    Oct 2019
    Location
    Dordrecht, The Netherlands
    Posts
    4

    Default

    Power supply looks te be H7835 , used in V103 terminal. ??
    The small board, 5412528, looks to be H786 power board, found in DEC MINC11 or MDC23
    a mix and match?

    http://bitsavers.informatik.uni-stut...tics_Jul78.pdf
    https://amaus.net/static/S100/DEC/te...aintenance.pdf

  3. #3
    Join Date
    Apr 2014
    Location
    Dordrecht , Netherlands
    Posts
    169

    Default

    Think found it.
    Is a Dec monitor VT103 power supply.
    Seems to be the same.

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