RE: Static PET PSU questions

From: M H Stein <>
Date: Wed, 30 Sep 2009 19:56:54 -0400
Message-ID: <01CA4208.2C0CFA20@MSE_D03>
Pretty straightforward:

pins 1 and 5 are the ends of a center-tapped secondary,
pin 3 is the center tap and Cap -
pins 2 and 4 are DC returning from the board and connected together at 
the Cap +

The 320008-2 schematic is correct for the board.

If you've got ~9V DC available, just feed 9VDC to pins 2 and 3.

If you're going to use a PC-type PS, I'd pull the regulators (if they're not 
still out) and run regulated 5V to the 4 Vcc points and drop the 12V
to ~9 with a regulator or Zener and connect to pin 2.

But I accept no liability ;-)

X------------------ 1 ----->|------+
X                          CR1    |
X                                    |
X                                    |
X   +-----+------ 2 -------------+-----+----------------> 9V DC to regulators and Cass drivers
X    |    _|_                             |
X    |    _ _  C  23000/15         /\  CR3
X    |      |                               |   
X----------+------ 3 --------------------+----------------> GND
X    |
X    |
X    |
X   +------------  4 -------------+                   
X                                    |
X                                    |
X                          CR2    |
X------------------- 5 -------------+



From: 	Ethan Dicks[]
Sent: 	Wednesday, September 30, 2009 5:34 PM
To: 	cbm-hackers
Subject: 	Static PET PSU questions

Hi, All,

Back on that 2001-8 board... it's a P/N 320008, original board.  It
has a 5-pin power supply connector.  From the schematics, pin 3 is
GND, pin 2 is unreg 9VDC, and there's a pair of half-wave diodes from
pins 1 and 5 to pin 4.  I want to run this board in a more modern PET
chassis (so far I've been using external +5VDC through TP1 down by the
internal cassette port).  I've never been able to locate a
chassis-specific schematic of any PET to match up the rectifiers and
regulators on the board with the transformer and filter cap in the
chassis.  Can anyone point me to such a document on or
anywhere else?  I have the general idea of what needs to happen, but
I'd rather not fry my only #320008 board trying to put it someplace
"interesting" because I failed to understand some important detail.



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Received on 2009-10-01 01:00:05

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