Commodore 16 Power Supply

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Tue Aug 8 02:30:04 2000

> Hi folks,

Hi folks too! It's over four months since I was last on Classiccmp, and I
almost feel I need a delurk!

> I recently stumbled across a Commodore 16 power supply. I'd like to keep it
> on hand as a spare. But I'm a little worried. The output is specified as
> 9.5VDC, but when I measured with my DMM, I got 14VDC! I didn't know if it
> needs a load to bring it down, or if the PS is just shot.
>
> Any thoughts?

My thoughts:

These beasts use 5V for the logic, and somewhere around 9V (not critical) for
tape motors and things.

A 9.5V power supply is bound to be unregulated (why regulate it to a voltage
that's not critical when all you're going to do is regulate it again to the
voltage that is). Recent threads have pointed out Commie machines of that date
with regulators on the board. And finally, the two voltages in the PET (the
Commie with which I'm familiar) are 5V (regulated) and 9V (unregulated) (FWIW,
the PET 8296D just took 5V and 12V from a SMPSU, but that was a special case -
an internal disk drive wanted 12V fairly well regulated for motors)

So I am 99.99% certain that it just needs a load to bring it down.

To test it, the easiest load to use is an auto bulb. A stop lamp / indicator
bulb is rated about 2A at 12V (well, 21W is 1.75A). Stick that on the output -
the bulb should survive if it remains up at 14V, but I expect you'll see it come
down to about 10V.

Just my 2d worth.

Philip.







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Received on Tue Aug 08 2000 - 02:30:04 BST