A5000 - diving in at the deep end!

[rubber_jonnie]

OK, so some tentative good news.

I replaced IC46 on the A5000 earlier today and it has been running stably since with all the RAM installed, the FDD and the IDE drive.

Given that it has been failing over from any point after booting and has never managed about 10 minutes without crashing, and that it has now been running for a good 8 hours with no issues I'm prepared to believe it is fixed, but I shall leave it on overnight and see what it's doing in the morning.

If all is well I'll add the BlueSCSI drive and adapter cards back in and see if it will boot properly from SCSI again. Fingers crossed.

[HigashiJun]

[rubber_jonnie]

Well, it's running fine still after leaving it running all night so looking good

Let's hope once I get the BlueSCSI installed it'll boot fine and I can still get my customised desktop and all the network configuration running again.

[stephen_usher]

Is IC46 a demultiplexers?

[rubber_jonnie]

Is IC46 a demultiplexers?

It's a 74HC573 Octal latch, you can see it's position in the schematic here, one of three IC's that look to be dealing with ROM addressing:

Screenshot 2025-01-26 at 09.27.26.png (472.56 KiB) Viewed 47 times

Given I've been getting errors like this:

IMG20250116115307.jpg (203.69 KiB) Viewed 47 times

Which suggests the OS can't find something in the ROM it makes some sense. It was these three IC's that were indicated as a possible cause over at Stardot.

I replaced IC46 first because it was closest to the battery damage, no other reason.

I considered if I should replace the other two, but I'm going to leave it as if it's working I don't want to replace just for the sake of it. I have more spares now so if I start seeing more issues then I can replace them all.

[HigashiJun]

Well, it's running fine still after leaving it running all night so looking good

Let's hope once I get the BlueSCSI installed it'll boot fine and I can still get my customised desktop and all the network configuration running again.

Should be good.

No reason the BlueSCSi wouldn't work (unless the Blue SCSI itself is dead).

[rubber_jonnie]

Well, it's running fine still after leaving it running all night so looking good

Let's hope once I get the BlueSCSI installed it'll boot fine and I can still get my customised desktop and all the network configuration running again.

Should be good.

No reason the BlueSCSi wouldn't work (unless the Blue SCSI itself is dead).

I'm hoping it'll be fine too, AFAIK the BlueSCSI itself is fine, I could see the disks, it's just being able to boot from it. I'll check the boot options again but IIRC it was already set to boot.

I'll have a look at it soon and post the results. I do have another BlueSCSI in my Mac Classic that I could use at a push.

[rubber_jonnie]

Well, I came through to start testing with the BlueSCSI and it had crashed...

I hit IC45 with cold spray to see if it made a difference and now it won't boot at all..

Back to the bench

[HigashiJun]

Well, I came through to start testing with the BlueSCSI and it had crashed...

I hit IC45 with cold spray to see if it made a difference and now it won't boot at all..

Back to the bench

Ah, bummer !

[rubber_jonnie]

I replaced the other latches and now it refused to boot...

So I put one of the old latches back, IC36 which seems to have control over the lower ROM address lines, and it's booting again. Will leave it for a bit and see if it fails again.

It's not unknown for a new part to be bad, so you never know. I do have other new spares but for some reason I took a punt on the old IC36...