ACA1221 can not go higher than 21 Mhz

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Don't Panic. Please wash hands.
  • I am trying to get my ACA1221 to go 28 Mhz on my A1200. However the machine goes into a resetloop when I add "acacontrol s 3 >NIL:" in my startup-sequence (second line). 21 mhz works fine with "acacontrol s 2 >NIL:".


    I use "acatune -maprom A1200.47.111.rom" to upgrade to 3.2.2 roms in the first line.


    I have removed the capacitors mentioned in the wiki, so I am a bit lost for new ideas :/


    I have read somewhere that you can upgrade the firmware on the card. Is that a possibility for a user?


    Thank you in advance.

  • Is this really an ACA1221, or is it a later version (ACA1221ec or ACA1221lc)?


    If it's really the very first ACA1221: Is it licensed for 28MHz? And are you aware that this used to sell as a 17MHz card?


    There is no user-upgradable firmware with any of the ACA1221 cards.


    Jens

  • OK, if the previous owner has upgraded it with all there is, he/she may not have done a trial run with top speed (only one trial run used indicates exactly that). Usually, a better power supply will make the card more stable at higher speeds.


    Card# CTm2Q has a ceramic CPU with mask 2B47K. This is a 1.5µ mask that may not run faster than 21MHz. Still, a better power supply is what I'd try (avoid the ones with MeanWell chassis).


    Jens

  • I have personally upgraded it with more memory :) Can not say if it has been tested at top speed.


    Power supply wise I am running a hiqh quality power supply from Lotharek:


    And the board was recapped before I bought it.


    There are physically 3.0 kickstart roms in it but I maprom to 3.2.2. See attached screenshot of the startup-sequence. Works fine with 2 but crashes with 3.

  • Power supply wise I am running a hiqh quality power supply from Lotharek:

    That's not high quality, but the exact crap I'm warning everybody from even putting it *near* their expanded Amiga. It uses a MeanWell chassis that is not suitable for distant loads, hence it is not suitable for an Amiga. You've been fooled - return the unit for false advertising.

  • Well ... I am now (almost) sure that the problem is with the accelerator.


    I got hold of an CA-PSU (that was not easy btw) and still the same problem. The computer freezes when I try to go from 21 to 28 mhz. See attached foto. And the same when I add "acacontrol s 3 >NIL:" to line two in the startup-sequence.


    I have also had the board rechecked and recapped by a pro technician I know. Just to be sure.


    I even sat the board in trial mode to see if there was an issue with the licenses. Cost me five trials but still the same.


    The board is rather old and the guarantee is gone ... But what to do?

  • I have also had the board rechecked and recapped by a pro technician I know. Just to be sure.


    I even sat the board in trial mode to see if there was an issue with the licenses. Cost me five trials but still the same.


    The board is rather old and the guarantee is gone ... But what to do?

    The board in the first line is the A1200 motherboard.

    The board in line two and three are the acc. :-)

  • Well ... I am now (almost) sure that the problem is with the accelerator.

    To be clear: The ACA1221 was sold as 17MHz accelerator for an insanely low price. There is no problem: It already does more than we advertised back in the days. The instructions clearly say that you should use the free trial runs to see if overclocking works, and only buy licenses if you've been successful.


    The board is rather old and the guarantee is gone ... But what to do?

    The 1.5µ mask of hte 68020 CPU is most likely the culprit. You can either de-solder the CPU and insert one with a faster mask, or we can proceed with the refund-procedure for the 28MHz license to "downgrade" it to 21MHz and get 10,- EUR back into your account.


    Jens

  • To be clear: The ACA1221 was sold as 17MHz accelerator for an insanely low price. There is no problem: It already does more than we advertised back in the days. The instructions clearly say that you should use the free trial runs to see if overclocking works, and only buy licenses if you've been successful.

    Ok. Was not aware of that. As mentioned I bought it used with a A1200. Got the impression form the wiki that 28 was standard.


    Just wanted to get the most out of the card. Replacing the CPU is a bit out of my league, thou :)


    Thank you for the offer of a refund. I have only bought more RAM for the card and that works fine so no sweat. Thank you for your time!