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intric8
Seattle, WA, USA
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Posted Fri Jan 13, 2017 11:15 pm

I have an A2000 that is having some very strange symptoms. I wonder if any Amiga folk (or hardware gurus) have any ideas that might help solve this?

Here's what I know:
- Motherboard rev 4.3
- GVP G-Force 030, 68EC030 @ 40 MHz, 16MB RAM. This also serves as an Impact Series II SCSI controller, which controls the internal SCSI hard drive.
- Drive that came with the machine was a Seagate 3.6GB drive.
- I've pulled the old battery, which was leaking, although the leak damage didn't look extensive.
- KS 3.1 ROM

When I boot the machine the screen is black. However, if I wait for a very long time (like, enough time to go eat dinner and return) it can eventually seek a floppy and either 1) show us the famous "enter your WB disk" or 2) boot from a WB floppy if one is in the drive.

By the way, when it is sitting there with a black screen every couple of minutes you can hear the HD being hit, cycling, then stopping. Sounds normal. LEDs work, too.

If I boot WB there are no drives mounted on the desktop. If I run HDToolbox it does not see any hard drives.

OK, so first I checked to make sure the G-Force was seated. Then I pulled and reinstalled all of the expansion RAM in the card. Then I removed the hard drive, and used a backup Quantam drive (much smaller, less than 400 MB).

Using the smaller drive produced the exact same results. I pulled all of the RAM off the card. Same results.

So then I pulled the G-Force card, and installed an Impact A2000-SCSI+8 card to drive the hard drives instead, fearing the G-Force might be toast (or the card slot itself). I put the Impact card in a different slot. This eliminated at multiple variables (slot, RAM, card, not to mention the accelerator processors on the thing).

But the different card, and different hard drive produce the same exact results.

If I wait for, well, forever, I can use the floppy and use the machine for floppy-only use. There is probably a jumper on the motherboard somewhere dictating the order of operations. But this machine has to use a hard drive. It's kind of a waste otherwise.

All of the cables are firmly seated, too. They appear to lead to the SyQuest drive (which also can't mount disks), floppy and hard drive. I suppose I could remove the SyQuest from the equation and see if that matters.

Any ideas, guys? It's like the motherboard refuses to hit hard drives. Oh - but it does recognize the RAM and processor on the G-Force, even though it does not play nice with the hard drive. I think the G-Force is OK.

Is this motherboard fatally ill, or am I dealing with something fixable here?

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terriblefire

Posted Sat Jan 14, 2017 7:59 am

Does the machine boot with just a 68k in there?

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intric8
Seattle, WA, USA
Website

Posted Sat Jan 14, 2017 8:49 am

terriblefire wrote:Does the machine boot with just a 68k in there?
Do hou mean if I remove the G-Force and try to just fire it up? Or do you mean the G-Force, and also unplug the drive(s) cable from the mother board?

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terriblefire

Posted Sat Jan 14, 2017 1:23 pm

intric8 wrote:
terriblefire wrote:Does the machine boot with just a 68k in there?
Do hou mean if I remove the G-Force and try to just fire it up? Or do you mean the G-Force, and also unplug the drive(s) cable from the mother board?
Yes. Trying to figure out if its a dead drive or a dead motherboard. See if to pops straight to the kickstart screen if you run it on the 68K only.

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intric8
Seattle, WA, USA
Website

Posted Sat Jan 14, 2017 1:57 pm

Well I removed the G-Force and unplugged the Drive cable from the motherboard and it never booted at all after leaving it for an hour.

I do find it interesting that I was able to get to the disk insert Screen if everything g was plugged in, but I've only ever seen that once so far.

My next test will be to remove all of the drives and ensure the CPU is fully seated. I think it has some sort of upgrade board sitting on top of the chip.

I'll take some pics in a bit.

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intric8
Seattle, WA, USA
Website

Posted Sat Jan 14, 2017 5:13 pm

So after pulling everything out of the way, I discovered this machine is running a MegaChip Plus, not an original CPU.

The mboard will not boot to the insert disk screen, fwiw.
Attachments
IMG_6494.JPG

User avatar
terriblefire

Posted Sat Jan 14, 2017 5:27 pm

I would reseat that MegaChip and the clip.. check it for corroded pins.

Then double check that clip is on the right pin on the CPU.

Then try a different CPU.

:/ Doh. This one looks complex.

User avatar
terriblefire

Posted Sat Jan 14, 2017 6:28 pm

intric8 wrote:So after pulling everything out of the way, I discovered this machine is running a MegaChip Plus, not an original CPU.

The mboard will not boot to the insert disk screen, fwiw.

Could be the light but that MegaChip doesnt look like its sat flat.. right hand side (as you see it in the pic) looks raised.

User avatar
intric8
Seattle, WA, USA
Website

Posted Sat Jan 14, 2017 7:53 pm

I pulled the megaChip and reseated it. Then I pulled that weird clip from Gary and put it back where it came from.

I read the megaChip manual, which I have, and it explains that when you install it two things must be done. First, you need to ensure you have the correct version of Agnus. Second, during the installation you actually have to cut a tracer between two points on the motherboard. So, basically, when you go megaChip, it's not easy to ever go back.

The previous owner did all of the mods and cut the board as directed. He also put the original Agnus (from 1988) in a little baggie and bought (presumably around 1990) the upgraded Agnus for the megaChip. So, I have the old Agnus, but I can't just pop it back in without soldering the motherboard.

Like you said, it's complicated.

Realistically, I have a 2nd 2000 that is functioning perfectly. The only issue it has is that it can't see its SyQuest drive. So, as each test I try continues to fail, I feel more and more like I have large collection of back-up and enhancement parts for the working one. I have extra hard drives, a floppy, an expansion card, upgraded ROM to 3.1, etc.

So, I may just migrate some things over and save the rest for whenever something ultimately fails due to old age.

I'm extremely tempted to move over the KS ROM, upgrade WB to 3.1, bring over the G-Force card (which has 16MB of RAM) and maybe see if the other SyQuest drive works. Then, whatever's left after that put into storage. That would be one rockin' 2000. It's already quite nice (2MB chip, 8MB fast) and WB 1.3 is really easy on the eyes. Since I love the early games more than the AGA, part of me wants to keep it the way it is. But I'm so used to WB 3.1 and the better UX (not the look, but just what you can do with it more easily) I may upgrade it. That's the way the previous owner's daily machine was set up. The one I'm using now was his storage/backup. I may try to bring it to his original machine's glory. I've got all the stuff.

Check out the insane monitor I have attached to the working 2000. It's a 16" Princeton Graphics monitor, which came equipped with multisync/multiscan. It's one of the very few non-Commodore 3rd party monitors that runs at native Amiga output. It's extremely nice, albeit extremely huge.
Attachments
2000.jpg
A2000 with 16" Princeton Graphics Multisync monitor


User avatar
Bulletdust

Posted Sun Jan 15, 2017 1:51 am

Can you take some shots of where the battery was?

If anything is going to go wrong, that's the most likely location.





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