ACA500+ not working with Kickstart 3.1

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Don't Panic. Please wash hands.
  • The machine:


    ACA500+, purchased new from icomp, there was never a time that the problem did not occur.


    Amiga 500 NTSC, 1.3 kickstart ROM, motherboard rev 6a, ECS agnus, 512kb in the trap door (problem still occurs without it) with the mod to make the 512kb slow ram into chip ram. I have owned the Amiga for several years, and no other mods have been done to the best of my knowledge. The machine works fine with Workbench 1.3 and all NTSC software that I own.


    The problem:


    Starting the Amiga with Kickstart 1.2 and 1.3 work normally. When attempting to start with Kickstart 3.1, it results in a blank DisMo, black CRT screen, and a dim green LED light on the ACA500+. There are no other colors before the black screen. There was one time when doing the virtual floppy install method to install Workbench to the virtual hard drive, that it said something along the lines of "unpacking floppy 2 of 7". I may have this message a little off, because I was only able to see this happen once.


    What I have attempted:


    1. Checked voltage coming from power supply, 5.1V and 12.1V.

    2. Cleaned edge connector with IPA.

    3. Tried 5 different CF cards in the boot slot, from 64mb to 1gb, Kingston, Sandisk, and some other brands I forget the name of. Also tried it without any CF cards.

    4. Tried several methods of going to Kickstart 3.1, including pressing F1, F7 for both normal and virtual floppy install, and pressing F to update flash.

    5. Gently made sure that ACA500+ is fully inserted, several times.

    6. Inspected the ACA500+ and my Amiga motherboard for dirt, bad caps, broken components, burnt parts, bent visible pins, or any other visual issues.


    Please help, thanks.

  • with the mod to make the 512kb slow ram into chip ram.

    I guess this is just the two steps:


    1) switch off the trapdoor mem expansion (switch, jumper or Exram line)

    2) highest address line to Agnus changed to A19


    Please confirm that there are no other components, especially on/under the Gary chip and the processor of the main board.

    There was one time when doing the virtual floppy install method to install Workbench to the virtual hard drive, that it said something along the lines of "unpacking floppy 2 of 7". I may have this message a little off, because I was only able to see this happen once.

    This may indicate that you have set the maximum frequency in the global settings to something higher than 21MHz. What many people miss in the documentation is that during Kickstart-unpacking, the speed is set to that maximum speed, regardless of the speed that you have chosen in the profile - that will be set *after* Kickstart unpacking. This was done in order to keep these unpacking-times as short as possible.


    If you've set such a higher freuqency, please dial back to 21MHz for the "big DisMo" version, and to 14MHz for the "small DisMo" version of the ACA500plus.

    1. Checked voltage coming from power supply, 5.1V and 12.1V.

    That sounds good, but the numbers are worthless unless you have also measured ripple and given the calibration date of the volt meter. The exact type and age of the PSU would also be of interest. Further, your monitor solition is also of interest, as some converters provide back-voltage to the Amiga, causing funny behaviour in some cases, and damage in other cases.