Re: C64 Problem

From: fachat (
Date: 2005-06-27 23:13:57

Hallo all,

many thanks for all the replies. Interestingly enough I found
something else - the original owner sent his IEC cable and with
this cable it works, with my other one it does not. So probably
this cable has some fault. But with the original cable (that
was forgotten in the first package and only came later) the 
thing works. So I have no reason to give it back, as it was 
delivered what was promised. Don't know what happened
technically, though. I guess I have to test some more, but I don't
really have time for it now.

In fact I found that the C64 has the old motherboard (like in the
breadbox machines), so this is a nice backup for my own old
C64 (which has a lot of modifications but, at least the SID is
already broken).

Thanks again,

On Mon, Jun 27, 2005 at 01:04:29PM +0200, Baltissen, GJPAA (Ruud) wrote:
> Hallo Andre,
> > Anything out of spec. here could make the circuit sensitive
> > to variations in the 5V supply.
> I was thinking in the same way as William. And it can be tested in a simple
> way:
> - pull ATN, CLK and DATA low
> - connect all lines, except RESET, to ground
> and see what happens.
> And then do the same for the drive and see what happens then.
> And as last do the same with drive and C64 connected.
> Next thing that comes to my mind that the C64 or 1541 has a bad 7406. The
> value of the used pull-up resistors for ATN, CLK, DATA and RESET can vary
> within 10%. Imagine that both the C64 and 1541 have some resistors on the
> low side of the scale. That means that one of the 7406 gates has to sink
> more current than on average. And I can imagine that a faulty gate can
> influence the rest of the IC. This can be tested by simply adding an extra
> drive.
> I hope this helps a bit.
> --
>     ___
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>   / /  |_/     Groetjes, Ruud
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