From: Baltissen, GJPAA (Ruud) (ruud.baltissen_at_abp.nl)
Date: 2005-06-27 13:04:29
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.
--
___
/ __|__
/ / |_/ Groetjes, Ruud
\ \__|_\
\___| URL: Ruud.C64.org
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