ACA500Plus issues

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Don't Panic. Please wash hands.
  • HI.

    2x ACA500Plus boards arrived today, Thanks Jens.

    My mate brought his amiga round to mine and we tested them both. They both seem to work fine on his, but on mine they dont.


    On mine they startup to the menu, I can see the options, and the parallax star-field, but the keyboard is frozen, so I cant select anything, and the board itself is displaying 99.
    On my mate's amiga both start up ok, and they both show FE on the display. He can then select a profile and boot it.
    we went right back to stock on both machines, removing the trapdoor expansion, and the rom switcher on mine (put 1.3 back on the board). this made no difference.

    Both Amiga's are Rev 6A, Mine is from 89 and is a green PCB, and his is from 91 and a brown PCB. Both machines were running on the same PSU, a Meanwell RPT-60B
    Interestingly, it is significantly more difficult to install the card on mine than on his, making us think my PCB is thicker.


    Also, my Action replay MkIII is working fine on this Amiga

    I'm completely out of ideas.

  • Meanwell RPT-60B

    That's no good for an Amiga, as it lacks important regulation features. Please use the original Commodore PSU instead.


    On mine they startup to the menu, I can see the options, and the parallax star-field, but the keyboard is frozen, so I cant select anything, and the board itself is displaying 99.

    Please try to move the keyboard from his tomputer to yours. If you already see the menu and moving star field, the startup/self-test has completely passed, and the DisMo shows the keyboard scan codes that come from the keyboard. If you see an unexpected number and keyboard doesn't react while everything else appears to work, you might have a defective keyboard.

  • That's no good for an Amiga, as it lacks important regulation features. Please use the original Commodore PSU instead.


    Please try to move the keyboard from his tomputer to yours. If you already see the menu and moving star field, the startup/self-test has completely passed, and the DisMo shows the keyboard scan codes that come from the keyboard. If you see an unexpected number and keyboard doesn't react while everything else appears to work, you might have a defective keyboard.

    Can you explain the concern around the Meanwell PSU? this is one i built myself into an Amiga PSU housing (to replace a dead switch mode PSU that was beyond economical repair, having failed twice previously). My only alternative is a heavy Linear Amiga Supply, which i haven't recapped.


    Swapping the keyboard is one thing that we didn't do. but the keyboard works perfectly otherwise. anything i can do to explore this further, until my friend can bring his around?


    Thanks

  • Can you explain the concern around the Meanwell PSU?

    That's a quite complex topic, and we've tried to cover it in this article, which is still WIP, so we will continue to work on it in the next few weeks before we officially publish it: http://wiki.icomp.de/wiki/Powersupply_FAQ

    Swapping the keyboard is one thing that we didn't do. but the keyboard works perfectly otherwise. anything i can do to explore this further, until my friend can bring his around?

    Since everything points to an error in your A500, it may be a simple CIA failure. Try to swap the two CIA chips for each other (they are identical, just serve different purposes in the different positions) and see if it makes any difference.

  • That's a quite complex topic, and we've tried to cover it in this article, which is still WIP, so we will continue to work on it in the next few weeks before we officially publish it: http://wiki.icomp.de/wiki/Powersupply_FAQ

    Since everything points to an error in your A500, it may be a simple CIA failure. Try to swap the two CIA chips for each other (they are identical, just serve different purposes in the different positions) and see if it makes any difference.

    Thanks. I'll give that a try.

  • Thanks again for the link. I've read it with interest and also the Commodore PSU spec document you link to. I can see why ripple might be a concern on the RPT-60B, and it's max p-p ripple in 80mv across all rails. The PT-65B has a max p-p of 50mv on the 5v rail, and 120mv and 100mv on the +12 and -12 rails respectively, so this brings it more inline with the commodore specs.


    Annoyingly i decided against a PT-65B as it wouldn't fit in the Commodore case, but i wasn't in possession of these facts at the time.


    Both of these Meanwell PSU's are regulated on the 5v rail


    My linear supply needs recapping which I can do, but from what I read on another thread here, that isn't necessarily a good choice either, my concern is that even with a commodore switch mode supply, given the age of the units and all the years of stress on the components within, I'd say it was rather unlikely that these are continuing to operate within those parameters today, but I'm no expert at all.


    I'll swap the CIA's over and get back to you later.

  • HI.


    Update. I swapped the CIAs. No difference whatsoever, Still started up at the menu with the starfield running, and the Dismo showing 99.


    I also ran Amiga Testkit and verified the CIA's and they check out fine; Same with the keyboard test.


    The next step is to swap the Keyboards over, though I wont be able to do this until the weekend.


    Watch this space...

  • HI.


    We have swapped the keyboards over. with my friend's keyboard plugged into my A500, the ACA500Plus starts up ok. With mine in it wont. so its definitely keyboard related.


    My friend's keyboard is a mitsumi, with a single wide tail off the membrane into the controller board. Mine doesnt have a brand on it, but has 2 narrow tails into the controller board. This keyboard has been with the machine from new (i've owned this A500 from new)


    I don't know where to go from here. To be honest I'm not prepared to go to the expense of replacing a keyboard that is functioning perfectly when the ACA500Plus is not plugged in.

  • Following up on this, the adapted software did not make a difference in this case. A test with the exact same keyboard here in our shop did not reproduce any issue. We therefore assume that the keyboard is defective, or it reacts piccy to the voltage drop caused by the increased load on the power supply.


    With another keyboard-related support case in the German part of this forum (where the cause is really a defective keybaord), I have decided to do some digging in our stock for spare parts. I've put the spare part in our shop now, but we won't be able to ship until next week, because we're moving the product database to a new server - this will take a few more days, and new products can't be added at this point.

  • The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.