Service Manual/Schematics for an IBM 7861-015 modem?

Ethan Dicks ethan.dicks at
Mon Feb 12 10:06:55 CST 2007

On 2/11/07, Brent Hilpert <hilpert at> wrote:
> Ethan Dicks wrote:
> > Had a good day at the Mansfield Hamfest today.  I now have [a]...
> > nixie-tube panel DVM...
>   ^^^^^^^^^^^^^^^^^^^^

>  If that is a Weston 1294-series DVM (4.5 digits, TTL, fits standard 4"*1.75"
> industrial instr. panel), I can supply the schematic.

It _is_ 4.5 digits (with individual + and - masked neon bulbs) and
does fit a standard panel opening, but it's an MDPM-3 by Instrument
Displays, Inc., of Haverhill, Massachusetts.

>  Neat find, as LEDs quickly took over the market for such panel meters, the
> NIXIE tube ones are not common.

They sure did... one day it was analog meters, nearly the next day, it
was LEDs.  The window for Nixie tubes was rather small.

I couldn't believe I saw this one on the table for $3.


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