Quote:
Originally Posted by byteoftce
A new intermediate...
I have now replaced the HCT4046AMG4 from TI with a 74HCT4046AD from NXP as a test. Unfortunately, the problem has gotten worse. Now I have to switch the Amiga on several times until it boots and the dependency of the resistor R3 is even more difficult to set (10-20 ohms). I also replaced the capacitor C9 (100p) with a different batch as a test. When the Amiga boots everything runs stable, otherwise a green screen appears when switching on. It becomes problematic if I install the card in a second Amiga. There the resistance must be set differently again until the card runs. So it also depends on the Amiga itself (tested with 4 Amiga 500 Rev.6).
I'm still wondering if it makes more sense to tap the clock at Gary (CDAC pin 26), but I'm not sure if that's correct. More precise results will probably only bring the oszi which I'm still waiting for at the moment....
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I still suspect some other component having the wrong value. C10 should be 100n (C10 is not very critical though), C11 and C15 should both be 22p (pico!).
The NXP parts are generally high quality. It shouldn't be that sensitive.
But yeah, give CDAC a try. I put that option in as a fallback when the PLL is not working. So far I haven't heard from anyone that they had severe problems with the PLL but as you do have them: try the CDAC option.