7 Feb
2025
7 Feb
'25
9:18 a.m.
On Fri, Feb 7, 2025 at 5:08 PM William Sudbrink via cctalk
<cctalk(a)classiccmp.org> wrote:
I'm repairing/restoring a later model MITS 8 inch floppy drive. I can not
seem to find schematics for it. It is
Is it simple enough to trace out the schematic?
the same as Bill Degnan has here:
https://vintagecomputer.net/MITS/88-DCDD/
You can see in his photos (and mine match) that the _plus_ 24 volt DC supply
on the board uses a 7924 (note the
9. negative) voltage regulator, with a small heat sink, directly on the
circuit board. Along with a couple of 7805s,
Remember 'There is no such thing as ground' You can take any point in
a circuit as your reference.
The so-called positive 3-terminal regulators have the negative
terminal common between input and output. The negative regulators have
the positive input and output terminals commoned.
So if the input to a 7924 comes from a 'floating' supply (neither side
of the input supply connected to anything else) it would be fine to
connect the output of the regulator to the connection which is
commonly regarded as ground, at which point the common terminal of the
regulator (and the +ve terminal of the floating supply that feeds it)
is +24V.
-tony