ASR 33 buzzing

[tony duell]

> Good question.  I only thought motor because it seemed like the noise was
> from back there.  And when I put a plastic tool against the outer casing, I
> could feel a vibration.  But now I'm wondering about that paper tape reader..
> when I listened to the noise again it did kinda sound like it might be coming
> from over there.  It's kind of diffuse.

I would start disconnecting plugs in an attempt to silence the noise (and thus
determine the faulty section).

Pull out plug 4, which will isolate the motor and receiving magnet coil

There should be a PSU for the reader in the stand. Unplug the cable
from it.

Unplug the cable from the control unit that handles reader control. I
think that's plug 3. It's certainly not 6, 7, 8 and I think that only leaves
one in a normal machine.

If it still buzzes it pretty much has to be something in the call control
unit chassis. Maybe the transformer for the magnet driver power
(shorted rectifier or something?) Or the line relay (but that should
not be powered in 'off' or 'local'

-tony