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    Mark II's....before I get too far



    Posts : 3
    Join date : 2013-07-20

    Mark II's....before I get too far

    Post by Backpacker85 on Mon Nov 25, 2013 1:41 pm

    I got a pair of Mark II's, a pair of PAM-1's and a DSC-1 with the intent to put them all back into operation. The original plan was to repair/replace parts "as necessary", but I'm now thinking about taking the Mark II's down to bare chassis and starting from scratch.

    My first question (of what I'm sure will be many....) has to do with the driver boards. These have the early (large) boards, and appear to be in good shape physically, but a mish-mash of mixed components between the two. What I'm looking for is a component layout of these boards with original values. I thought about replacing the boards with new, but really would like to keep the original size and not use a filler plate.

    I can find lots of details on the Mark-III boards, but nothing on these larger boards with a different component layouts.

    Am I being overly-optimistic thinking these can be rebuilt (or even replaced), or should I bite the bullet and go with new (smaller) boards?

    Any help/insight would be greatly appreciated.


    Posts : 496
    Join date : 2008-12-05

    Re: Mark II's....before I get too far

    Post by PeterCapo on Mon Nov 25, 2013 9:22 pm

    The Mark IIs, especially the earlier ones, were not all made exactly the same.  I have seen different versions of the schematic showing two, three and even more variations in the circuit.  If I recall, there were different parts on the PC board from one revision to another.  Also, some Mark IIs used the Biaset system while others did not.

    As a starting point, I suggest studying the two you have and note any differences between them.  Then, see if you can find the version of the assembly manual, schematic and pictorial diagrams that match both or each of them.  Restoring them with an eye toward retaining as much of their originality as possible is doable, but it will take research to get your bearings as well as a lot of patience and care, i.e., reworking those old phenolic PC boards is problematic even with really good soldering/desoldering equipment.

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