Steve wrote: ↑Tue Jun 01, 2021 4:18 pm
Exxos for educational purposes could you please describe how you realised the clock line needed that resistor,
I used the best diagnostic tool available,"finger on board" = works
Steve wrote: ↑Tue Jun 01, 2021 4:18 pm
and as a side note do you have any idea why this falcon might be different to others? Thx
It's just "dumb luck" with this stuff. Its very hard to design a "one size fits all" fix for machines when every Falcon has different odd quirks with it. Now I am aware of this issue I will update my website to mention it as it may help others in future.
My clock board needs some small loading to function correctly (hence adding the 100K) but normally the SDMA is enough to load it and things are happy. On this Falcon, nope. For some reason it's not enough. Signal just looks bad, lots of ringing, The voltage if I remember rightly looks higher on the clock than it would ordinarily be as well. Could be some slight harmonic resonance going on somewhere around 100mhz. It could just be this board inherently more noise problems. Though this resistor is only relevant to my clock board anyway. It won't help just adding 100K on it on any other clock boards.
Unfortunately these things are a lot of guesswork. I mean if I had personally fitted and tested a batch of 1,000 Falcons, then a lot more would be learned and diagnosed right at the start.. But of course such things cannot happen. So I really have to make best guesses on how to fix problems, so it is just inevitable that every now and again a Falcon will malfunction.
The clock patch has solved the original noise problems in any case. Just this Falcon needed some a bit extra to get it to behave. #WelcomeToAtari