Posts by SpaceFlightOrange

So, this is strange.

I was booted into Workbench 3.1.4 on the CF card with the 3.1.4 image mapped in and i ran "The Emulator" (An old BBC Micro Emulator - This is really a 1.3 era piece of software). I pressed a key trying to reset the emulator when the tv signal disappeared (the Tv no longer detected a signal from the SCART interface) and a weird, almost buzzing noise was coming from the TV speakers.

ACA started showing 8.8 on the dismo and the dismo light was bright white. I reset and the machine booted but the dismo wouldnt clear, and when i went into the ACA menu the dismo was showing weird things, essentially a single segment on each digit was lit. I powered off an on, and it booted straight into the ACA menu, which it shouldn’t, because i have it configured to autobooot into expert profile #1, and the RTC on my trapdoor expansion had reset!!!

The main Config (f8) was fine, but my main expert profile (#1) had been wiped!! My other 2 profiles were intact

I removed the ACA and started the machine up and rant AmigaTestKit. All seems fine though that confirmed the clock had reset.

I've re-inserted the ACA and reconfigured my profile and everything seems fine now, but I was sweating for a while there! is this anything i should be worried about?

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.

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...

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.

Quote from Jens

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.

Quote from Jens

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

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.