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From: Suudy on 9 Apr 2008 11:30
On Apr 8, 7:55 pm, rusure <r_u_s...(a)mybluelight.com> wrote:
> On Apr 8, 12:15 pm, Suudy <pet...(a)mudplace.org> wrote:
>
> >  it shows the power after the rectifiers and voltage
> > regulators, i.e. the DC outputs.  I was looking for the power
> > immediately after the transformer, the low voltage AC.
>
> 2 types of power supplies were made by Commodore.  Each had 12 and 5
> volts DC power sources..  Each had 500 mili amps with the 12 volts
> power.  Some of the PSU had 700 mili amps comming out with the 5 volt
> source and some had 1000 mili amps (1 amp?) comming out with the 5
> volt source. Many power supplies had 5 and 12 volt power sources with
> higher amperage ratings.  I would be SHOCKED if any used circuitry

The power supply ratings are interesting to me because it tells me the
kind of power the 1541 was designed to consume. Whether the circuitry
and motors actually consume that much is a different question, but at
least I know what the upper bound is.

> identical to either of the Commodore power supplies.  I hope the
> internal power supply circuitry is important to you.

I am looking to possibly use the low voltage AC from the transformer
for my own power supply to drive my own circuitry. It is kind of a
future pet project idea right now, but it would require using the
connector from the transformer up to the board, the the AC side. So
in this case the power supply circuitry is important to me.

I want to make sure the power supply I may implement is capable of
sourcing enough power.

Thanks,
Pete
From: Suudy on 9 Apr 2008 11:34
On Apr 9, 7:42 am, bluebirdpod <bluebird...(a)gmail.com> wrote:
> On Apr 6, 12:08 pm, Suudy <pet...(a)mudplace.org> wrote:
>
> > I'm probing around in my 1541 (Rev C, PCB #1540050) and I'm trying to
> > figure out the supply voltage from the transformer to connector P1.
> > Looking around on zimmers, the schematics don't really identify what
> > the voltages are at the connector.
>
> > Now, the only hint I've seen is on the short Rev E schematic (http://
> > tinyurl.com/4byav7).  This shows the transformer, and the outputs of
> > it going to the rectifiers.
>
> > My probing shows about 16.6Vac between pins 1 and 4, and 10Vac between
> > pins 2 and 3.  Does this seem right?  Anybody have any insight into
> > this?
>
> As long as the recified and voltage regulated power is correct, it
> really does not matter what the low voltage AC is, yes it has to be

In my case it does. I'm thinking of using this LVAC as an input to a
power supply for a pet project. To this end, I was trying to figure
out the winding ratios in the transformer, but I can't find a part
number or any other info.

> higher than the rectified voltage for amperage and voltage loss, but
> the 16vac would be supplying the 12vdc line, and the 10vac would be
> supplying the 5vdc line, if the LVAC was too high it would place a
> burden on the heat sink mounted rectifiers and cause excess heat and
> possible failure, just make sure your input AC from your wall outlet
> is between 110VAC and 125VAC and you should be fine, On the older 1541

That makes sense. I figured the 16Vac drove the 12Vdc line, and the
10Vac drove the 5Vdc. I just didn't know the actual power output.
Thanks to rusure's link, I think I know that now (12Vdc @ 500mA, 5Vdc
@ 1A).

Thanks,
Pete

From: christianlott1 on 9 Apr 2008 15:24
does this help?:

http://members.tripod.com/~ilkerf/c64tower/pow1541.html

From: Suudy on 9 Apr 2008 18:13
On Apr 9, 12:24 pm, christianlott1 <christianlo...(a)yahoo.com> wrote:
> does this help?:
>
> http://members.tripod.com/~ilkerf/c64tower/pow1541.html

A bit.

But I did find more through zimmers.

http://www.zimmers.net/anonftp/pub/cbm/schematics/drives/new/1541/service/Page_05.html

Explains the power supply. Just the info I was looking for!

Pete
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