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I have now also built 2 pieces of the Card.
Great work, but I had a lot of trouble getting the card to work.
R3 as a fixed resistor didn't work at all. Although the measuring voltage at J2 was 2.52V (4.7KOhm), the card did not start and there was a green or black startup screen.
I also tried it with 4.3K and 5.1K resistor. no chance :-(
Only after I used a 10K rotary resistor does the card work now. (set to 4.95K ohms (J2 2.94V).
If I only adjust the rotary resistor by 50 ohms, the card does not work.
To rule out other problems, I also tested different CPUs.
I tried MC68000FN16 / MC68HC000FN16 / MC68HC000FN20 / MC68010FN16 / MC68000FN12 (for the endurance test). The same problem with all CPUs. Since then, both cards have been running stably, only if the Amiga was off for 1 day do I have to start it 4-5x before the Amiga starts, after that it runs perfectly again.
As it seems it is very much due to the ICs used and their normal tolerances. Maybe this will help one or the other if he builds the card.
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