Re: Static PET PSU questions

From: Ethan Dicks <>
Date: Wed, 30 Sep 2009 21:45:53 -0400
Message-ID: <>
On 9/30/09, M H Stein <> wrote:
> Pretty straightforward:
> pins 1 and 5 are the ends of a center-tapped secondary...

Ah... there's the magic phrase.  I wasn't thinking of center-tapped,
so I was having visualization problems.

> The 320008-2 schematic is correct for the board.

Right.  That I knew.

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

I don't have ~9VDC at 2-3A lying around.

> 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.

Right... they _are_ still out, though I've cleaned everything up.  I
probably have a 7809 lying around somewhere (I do save such things
when I find them in CD players and consumer devices).

I was really just contemplating how to restore the board to work in a
real PET, mostly because of the video issue - I never did get that
simple video circuit to lock on the signal from the 3032 last year.  I
did _see_ the ROM BASIC splash message, but on a bog-standard
Panasonic B&W "security monitor" (that works with an 1802 and 1861,
BTW), I could never get the video stable left-to-right.

> But I accept no liability ;-)

That's OK.  Your initial comment and the follow-up picture explains it
all to me.  I saw the brown wires to the 5-pin plug and got about
18VAC from it, but never put 2+2 and figured "center-tap".



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Received on 2009-10-01 02:00:28

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