VAXen at home
ethan.dicks at gmail.com
Tue Oct 16 16:05:47 CDT 2007
On 10/16/07, William Donzelli <wdonzelli at gmail.com> wrote:
> > ...The RDM board is bad, but that's not required
> > to get the machine to run. It appears to be failure of
> > the RAM on the RDM board, actually. Which of course is
> > soldered to the board, and there is no diagnostic
> > routine to find out which chip is bad...
> Most (all?) RDMs for the VAX-11/750s were made from that odd circuit
> board process where wires are laminated right to the board (the name
> escapes me right now, and I will remember just after sending this).
Multiwire, as was pointed out elsewhere (though there's another
technology that we used for our VAXBI boards, called "Unilayer" which
is much like Multiwire, except, I think, the difference is that the
Unilayer wire nest is laid out on a bit of pressure/heat-sensitive
adhesive sheet, then bonded to the substrate as a unit, not one wire
at a time.
> Those boards could develop faults from the wires breaking.
I suppose that's possible, but unless there has been mechanical damage
or massive cyclical temperature shifts, I think the wires are somewhat
sturdy. I certainly can believe there's a bad SRAM on that board,
especially if they are 2114s or similar.
But as the OP said, it's not an essential board.
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