Re: CBM Power Supplies

From: Geoff Oltmans (
Date: 1999-07-22 21:40:05

On Thu, 22 Jul 1999, Bo Zimmerman wrote:

>   Those dadgum bricks just confuse the heck out of me.  I'm speaking of the
> big hunks of metal found in the PETs and CBM disk drives.  There is always
> the red, white, and black wires coming into them.  The black wire, however,
> is never ever used.  I used to think that these bricks were somehow 110V and
> 220V, with the proper choice between black and red being the determinate for
> proper operation.  This, apparantly, is a pipe dream.  Not so easy.  So,
> does anyone know what the "extra" black wire is for?

The "brick" you're referring to is actually the AC step-down transformer
that takes AC line level voltages and steps them down to the levels that
the system actually uses (can't remember the secondary voltage). Anyways,
you have two wires on one side that is the supply from the AC wall socket,
the primary winding. On the other side you have your three other wires.
Generally, AC transformers have three terminals on the secondary winding,
two at either end of the winding, and then a center tap somehwere in the
middle. The purpose is to supply two different voltages at the secondary
side. Chances are Commodore just got these transformers in bulk and didn't
need the center/end tap for anything.


This message was sent through the cbm-hackers mailing list.
To unsubscribe: echo unsubscribe | mail

Archive generated by hypermail 2.1.1.