From: William Levak (wlevak_at_grex.cyberspace.org)
Date: 2005-06-27 06:37:54
On Sat, 25 Jun 2005, fachat wrote:
>
> Hi,
>
> I recently got a C64C plus VC1541 (not VC1541-II!) from ebay,
> and it shows the following symptom:
>
> when I connect the new C64C with the VC1541, when I start loading
> anything from the disk, the C64 resets and the floppy hangs.
>
> So far so bad, I thought this is either the floppy or the C64
> hardware. Now when I replace the C64C with another C64C, it works.
> But, using the broken setup, when I replace the VC1541 with another
> VC1541-II, it also works!
> Anyone has an idea here? Both new (C64C and VC1541) have seemingly
> unbroken warranty seals - so it seems no hardware tinkering.
> Only the C64C had a plug on the tape connector with a
> resistor between the two outmost pins. It does not matter, however,
> whether this is plugged in or not.
Pins 1 and 2 are ground and +5 volts. It looks like someone attempted
some surge suppression.
> Another question: The new C64C has a serial number in the 100000s
> and an old-style (like my original C64) power supply. The other
> C64C has a brick-style power supply, it has a serial number in the
> 500000s. The pins in the power plugs of those power supplies
> are different. Can I actually exchange them?
They are interchangeable, but not identical. The external power supply
uses a transistor as the 5V regulator, but not necessarily the same
transistor. The reset is operated from this +5V supply. There are
several capacitors and a choke in the C64's +5V input and the reset
circuits. Anything out of spec. here could make the circuit sensitive
to variations in the 5V supply.
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