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Chris.LDN

Posted Sun Jul 25, 2021 12:23 pm

Thanks for your help everyone. Just wanted to report back some success (I think).

I replaced my 8520R2 CIA chips with a pair of 8520A-1


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Double click and clock is working, however running Amiga Test Kit still reported the same faults as before.

I decided to updated Amiga Test Kit to the latest version and it now reports less faults however 2 FAIL errors remain:

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I'm happy mouse and clock is working correctly so maybe I'm being pedantic. Should I be concerned about the Amiga Test Kit results or should I just get over it and enjoy my new Amiga 1000?

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iljitsch
Website

Posted Sun Jul 25, 2021 12:29 pm

It looks like the timing is slightly off, which isn't ideal but it looks like things are basically still working.

I'm not someone who knows about hardware in detail, but I believe these issues are not due to the CIA chips themselves but rather the timing systems that surround them. So I wouldn't worry about this enormously, but if you want to get to the bottom of it, look further than just the CIAs.

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Crispy

Posted Sun Jul 25, 2021 5:10 pm

The results shown for the timer test indicate that you have an NTSC A1000. The A1000 gets its timing for the CIAA TOD clock from the AC mains frequency, which in your case is 50 Hz, and the tests are failing because this frequency should be 60 Hz. I've run through the math using 50 Hz as the TOD clock frequency on an NTSC machine, and everything lines up with the test results you posted, so it looks like your CIA chips are working just fine.

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Chris.LDN

Posted Tue Jul 27, 2021 3:15 pm

Crispy wrote:
Sun Jul 25, 2021 5:10 pm
The results shown for the timer test indicate that you have an NTSC A1000. The A1000 gets its timing for the CIAA TOD clock from the AC mains frequency, which in your case is 50 Hz, and the tests are failing because this frequency should be 60 Hz. I've run through the math using 50 Hz as the TOD clock frequency on an NTSC machine, and everything lines up with the test results you posted, so it looks like your CIA chips are working just fine.
Thank you Crispy! You are a god!! :P

You are correct I am running an NTSC A1000 connect to UK 240V power supply. For reference here's the step down transformer I'm using.

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