Re: C-64 PSU

From: Ed Johnson <>
Date: Tue, 24 Apr 2012 13:29:30 -0400
Message-ID: <>
Seriously, we need calibrated equipment?

On Tue, Apr 24, 2012 at 6:57 AM, William Levak <> wrote:

> On Tue, 24 Apr 2012, wrote:
>  A question..
>> Since I have now quite a bunch of stuff sticking long way out of my
>> EXPANSION port and also some from the tape port - I am thinking to
>> eventually replacing my 30 years old and still reliable PSU. I have the one
>> with two fuses and a power switch, which is quite rare and I wouldn't like
>> to make it fail as it seems to get running quite hot with everything
>> attached. Now - what's the problem you may ask. The problem and question is
>> always the 9VAC. ALthough all the PSUs are rated at 9VAC, I recall that
>> they supply somewhere between 11V and 12V. Moreover I recall that back in
>> the days, when I supplied a "true" 9V of AC some things didn't work
>> properly on the 64. I don't remember today what was failing but I remember
>> that delivering a proper 9V didn't work out. Does anyone know why:
>> a) why PSUs rated as 9V (have to) deliver 11+
> Power supplies rated 9V appear to be at 11 or 12V, but actually are not.
> The 9V rating means 9V effective voltage delivered to the equipment at full
> power load.  To measure this, you would have to put a resistor across the
> power supply of sufficient wattage to match the maximum rated output of the
> power supply, and then measure the voltage drop across the resistor.  Of
> course, you would also need a calibrated voltmeter in order to get an
> accurate reading.
> SDF Public Access UNIX System -
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Received on 2012-04-24 18:00:42

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