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From: Suudy on 6 Apr 2008 14:08
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?
From: rusure on 8 Apr 2008 10:50
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?

The schematic of the 15?1 power port is
given near the bottom document found here:

http://personalpages.tds.net/~rcarlsen/cbm/pinouts.txt



From: Suudy on 8 Apr 2008 14:15
On Apr 8, 7:50 am, rusure <r_u_s...(a)mybluelight.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?
>
> The schematic of the 15?1 power port is
> given near the bottom document found here:
>
> http://personalpages.tds.net/~rcarlsen/cbm/pinouts.txt

Thanks for the link. This is helpful because it helps me understand
the power requirements of the board.

However, 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.

Pete
From: rusure on 8 Apr 2008 22:55
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
identical to either of the Commodore power supplies. I hope the
internal power supply circuitry is important to you.
From: bluebirdpod on 9 Apr 2008 10:42
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
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
non C version, there is a wire that is loose and heat shrink
protected, this wire is for re-wiring for 220VAC, one would remove the
Neutral line from the power plug and reconnect this loose wire to the
same location the neutral line was connected to. The C rev might also
have this, seems COMM used old stock to make part of the C rev 41's. I
have seen medium boards without the track 1 stop sensor in a C looking
case, and be a lever Newtronic mech. and the like, they used whatever
was leftover from many different assembly plants.

-BBP
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