User avatar
rebbi

Posted Thu Aug 23, 2018 7:19 pm

Hi, Folks,
I have a kind of Frankenstein's monster A1200, which I hadn't fired up in probably 5 or six years. Then, I needed access to a document from 1996 that I suspected was on that machine. So after some fiddling around with the hooked together Amiga, lo and behold, the thing booted and I was able to find the (Wordworth!!!) document I'd sought. This brought back some of that Miggy magic, and now I'd like to play around with the old girl on a more regular basis.

Here's the catch:
This is a very modified machine.
It's got an A1200 motherboard, fitted into an Ateo Concepts (anybody remember them??) tower case. There's a Blizzard A1260 accelerator board with the SCSI interface/fast RAM add-on board. The Ateo bus (essentially an ISA bus board) is fitted with an Ethernet board and Ateo's Pixel 64 RTG card (running Picasso 96, IIRC). There's a bunch of other stuff in the tower case, including a flicker fixer / scan doubler, a SCSI CD burner, a SCSI Zip Drive (!!!), Ateo's PC keyboard interface, an Eyetech doodad that mixes the CD drive's audio output into the Amiga's audio out, and probably a few other things I've forgotten to mention.

So, the machine has a funky boot-up process. From a cold start, it auto-reboots once... IIRC, this is something in the startup sequence that loads the 68060 libraries, or something like that. If left alone, the Miggy will then boot into the AGA chipset. But then, if I manually reboot with Ctrl-Amiga-Amiga, it'll boot into the RTG card (which sports a breathtaking 2 MB of video memory)! :shock:

My problem is that the ability of this machine to boot successfully is rather hit-miss, and I cannot determine why. Sometimes, it has frozen on one of the AGA diagnostic colors, indicating a hardware problem. When that happens, sometimes reseating the accelerator card, or even the fast RAM, will fix this, at least temporarily. Lately, the machine boots all that way to the gfx card like a charm, but then, after a period of time, it locks up and may not even respond to a keyboard reset, so that I have to power down and reboot.
I don't think that this is a thermal issue (as hot as the 68060 runs) because right now I'm running the machine with the tower case removed, so the innards are getting plenty of air circulation.

So...
How would you troubleshoot this kind of issue? Clean the contacts on the various PCB connectors? Something else?
I'm all ears, folks.
Cheers,
rebbi

User avatar
Dynamic_Computing

Posted Thu Aug 23, 2018 8:06 pm

You have a very interesting machine indeed! When my Amiga 1200 decides it does not want to boot it is usually because the accelerator card has moved or Twisted itself in a way where it does not make a good connection I find if I just give a little push on the accelerator card it usually boots up again. The real solution for me would be to put some little feet on the bottom of the accelerator card so gravity doesn't pull the right side of the card downwards and give me a bad connection.
Because it does lock up after period of use, it almost does sound like it is a connection issue that causes a problem after a period of time. In the past with PC'S I sometimes take a pencil erasor and gently rub the contacts of whatever is giving me an issue to remove any oxidation or other glupity guck that has accumulated there.
I would absolutely try it without the accelerator installed. See if it boots every single time with it removed. That would be a good way to test this Theory.

User avatar
rebbi

Posted Thu Aug 23, 2018 8:35 pm

I think this is a good suggestion and I’ll give it a go. In the case of this machine, the accelerator board sits on top of the Ateo bus connector, which in turn sits on the A1200 motherboard connector, and the accelerator is perpendicular to the floor, rather than parallel as it would be in an A1200 case. There’s enough give in the connector that the accelerator board can be moved a few degrees to each side, analogous to your example of your accelerator shifting downward due to gravity.
Thanks!

User avatar
femuruy

Posted Fri Aug 24, 2018 3:02 am

And rebbi ... you owe us some pics of it :)

User avatar
Zippy Zapp
CA, USA

Posted Fri Aug 24, 2018 7:49 am

Sounds like a neat machine.

Does it have the original capacitors? They are known to leak and it can cause stability issues. I am not saying 100% that is what it is, as it does sound like a loose connection too. Still it is worth it to examine the caps if they are original...

User avatar
rebbi

Posted Fri Aug 24, 2018 8:05 am

You know, it does have the original capacitors, because I bought the machine new mini years ago, and did all the modifications myself, and I know that the capacitors have never been touched. I have no idea how hard it would be to get the motherboard out of the case and take a good look at it. But it’s worth looking into. Although, like you, I suspect it’s the connectors, and not the capacitors. Thanks a bunch!





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