Mikael wrote;
> The shaft is a very light-weight array of printed copper strands on a hollow
> shaft. These copper strands are going along the shaft forming a commutator
> and there are 4 large magenets, square angled to each other surrounding the
> shaft. The shaft slides over the top of a fixed metal bar (part of the
> shell/case). The shaft is not physically supported at the end it slides into
> (where metal bar is attached) because enough support is provided via 2
> supports at the opposite end (the shaft encoder stage and main joint). The
> shaft is driven by 4 brushes on springs at 90 degree angles to each other
> and are doubled up to form a 2 wire dc motor which works smoothly in either
> direction (minus the squeeking) at an expected power level (200 mA @ 5 v).
>
> I haven't rung IBM about it jet thinking they would be the same as any other
> co but since you mention this i will give it a try :)
>
> One more thing to note, it has a stiker covering the protective cover of the
> shaft encoder circuitry saying "Caution: use capstan protective cover while
> cleaning vacuum columns". This looks quite clue-full, what is a capstan?
The capstan and the vacuum columns suggest a digital or an
instrumentation tape recorder as a mass storage. In such a device
the capstan drives a very short piece of the tape along the
read/write head in order to start and stop very fast.
Before and after that short piece of tape, the tape is sucked into
vacuum columns, where it forms loops. The vacuum columns are fysical
tape buffers. The reels are driven so that the loops in the columns
have a fixed length, which is monitored by one or more lamps and
photo diodes. The lengths of the loops is allowed to vary
considerable, as long as the capstan is fed sufficiently.
I shall try to make a rudimentary picture of it by symbols. I do not
sign the magnetic head(s), so, in reality, it is a little bit more
sophisticated. Look at it with a fixed font:
reel capstan reel
O __o__ O
\ / o \ /
|| || || ||
|| || || ||
||_|| ||_||
| | | |
|___| |___|
left right
column column
Try to find out whether this description fits in your mistery
treasure!
Regards, Harry
--
Author: H.C. Croon
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