ASR-33 problem

From: vrs <>
Date: Fri Jan 23 22:10:51 2004

> > Sorry, I mean Tx on the computer. The 20V appears on the + side of the
> > going to the TTY's printer, whenever the printer is actually printing.
> > computer doesn't like it much, either :-).
> I guess I'd start by unplugging the 9 pin connector on the selector
> magnet driver bracket. If you still get 20V on the loop, then there's a
> short somewhere in the wiring on the call control unit (probably on the
> relay). If not, then there's a problem in the selector magnet driver.
> There aren't that many components in there, so it can't be too hard to
> test the lot!

I found a 9 pin connector behind the selector magnet driver. I had to
remove the selector magnet driver and bracket to get at it. I disconnected
it, then put the selector magnet driver back in it's socket (left bracket
off for now).

I no longer get the +20V spikes on the line, so I guess the problem lies on
the selector magnet driver card?

BTW the thing chatters even in local mode now, probably because the selector
magnet is never doing it's thing?

So, is there a theory of operation somewhere for the selector magnet driver?
I can't follow what the schematic is doing at all.

I suppose I could remove the components and test them each out of circuit.

Received on Fri Jan 23 2004 - 22:10:51 GMT

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