General Category > LisaList2
Lisa 2 started throwing Error 45
dmark:
Has anyone in this community dealt with a fully deterministic Error 45 on your Lisa 2?
The Lisa 2 that I have on hand is one that came with a faulty PSU and battery leakage, but I repaired it and got it to a fully functioning state a few weeks ago, which I chronicled over at the TinkerDifferent forums. It worked perfectly for several weeks.
However, a few days ago I noticed that booting from floppy was becoming slower and slower, until it got to a point where it no longer boots from any floppy disk. When booting into LisaTest 3.0 in particular, it throws Error 45 (bus error). Booting into MacWorks leads to a Sad Mac with code 0f000a (Line 1111). Using a Lisa Office System boot disk just ends up with the system rebooting itself. It doesn't matter if I'm using the stock 400k drive and physical disks, or a FloppyEmu in Lisa mode. The same disks lead to the same exact outcome.
The '83 Troubleshooting Guide suggests that either the I/O Board, CPU Board, or Motherboard has a fault. Not terribly helpful! I've tried various combinations of memory boards, so that can probably safely be eliminated as a factor.
I went back and checked my repairs and bodge wires, tested the 5V rail on the I/O Board and -12V rail on the Lite Adapter board. Voltage levels are in spec, and there are no obvious signs of damage.
What I was doing leading up to the issue, was to play around with a newly acquired Sun Remarketing SCSI adapter board, using a RaSCSI to create and format hard drive images to install a MacWorks environment onto. It was running for a few hours at a time, and restarted quite frequently, so I wonder if the heat and activity caused some component somewhere to degrade?
And to preempt the question: I've *not* done a shotgun recapping of either of the modules. Caps that looked iffy, or tested out of spec, I've replaced. But it still has 90%+ factory caps.
Anyhow, grateful for any pointers how to further troubleshoot this poor Lisa!
rayarachelian:
--- Quote from: dmark on May 07, 2022, 02:02:20 pm ---Has anyone in this community dealt with a fully deterministic Error 45 on your Lisa 2?
...
However, a few days ago I noticed that booting from floppy was becoming slower and slower, until it got to a point where it no longer boots from any floppy disk. When booting into LisaTest 3.0 in particular, it throws Error 45 (bus error). Booting into MacWorks leads to a Sad Mac with code 0f000a (Line 1111). Using a Lisa Office System boot disk just ends up with the system rebooting itself. It doesn't matter if I'm using the stock 400k drive and physical disks, or a FloppyEmu in Lisa mode. The same disks lead to the same exact outcome.
--- End quote ---
So, indeed error 45 is a bus error, this happens when some device doesn't respond to the CPU in time. Question that's harder is which device. It might be the floppy controller since you've noticed issues there. 45 is also linked to the MMU as the MMU will throw bus errors if the CPU tries to access memory it hasn't mapped. Could be the adder/comparator chips or the RAM used as MMU registers or something messing with their signals or operation (dust? board corruption from an old battery leak? short? bad filter cap on the RAM used as MMU regs?)
Could also be RAM, but the RAM tests should catch that however.
I would remove all removable expansion slot cards, such as the SCSI board and trying to see if it goes away or not.
I'd clean the motherboard connector and the edge connectors on the I/O board, CPU board, and memory boards with a pink eraser, or DeOxit, etc and see if it goes away.
If you happen to have spare boards to swap out and test that might help narrow down the issue.
I/O devices can also cause error 45 in time if they're not responding as that too triggers a bus error but it will take much longer if DTACK is not signaled in time as that inserts wait states before giving up.
If your I/O board has socketted VIAs you could swap VIA 1 with VIA 2 to see if the behavior changes, but most likely you would have seen other VIA related issues if it was them.
sigma7:
--- Quote from: dmark on May 07, 2022, 02:02:20 pm ---The Lisa 2 that I have on hand is one that ... I chronicled over at the TinkerDifferent forums.
...
... I wonder if the heat and activity caused some component somewhere to degrade?
...
I've *not* done a shotgun recapping of either of the modules. Caps that looked iffy, or tested out of spec, I've replaced. But it still has 90%+ factory caps.
--- End quote ---
Thanks for documenting the process of bringing your Lisa back to life; always an interesting adventure!
Running your Lisa for a long time at a normal operating temperature shouldn't cause any problems, so AFAIK that doesn't change the approach to the troubleshooting task. Maybe you're looking for something that was thermal related, but since the problem now occurs hot and cold it seems it isn't any more.
Replacing damaged and particularly old caps in the PSU is recommended, but not elsewhere typically. Since the large ones on your video board were suspect I suppose those should be on the list too. Check all the PSU output voltages if you haven't already.
If there is another Lisa owner in your neighbourhood, swapping parts about will probably help to localize the problem quickly.
Do you have any test equipment beyond a multimeter?
AlexTheCat123:
I had a similar problem a month or so ago where the floppy controller started acting weird and the system kept giving bus errors. The problem turned out to be the 8T97 tri-state buffer at U2F on the I/O board. Looking at the I/O board schematics, that 8T97 buffers the /DTACK signal that goes back to the CPU and the absence of this repsonse from the floppy controller could definitely be causing your problem.
dmark:
--- Quote from: rayarachelian on May 07, 2022, 02:51:12 pm ---So, indeed error 45 is a bus error, this happens when some device doesn't respond to the CPU in time. Question that's harder is which device. It might be the floppy controller since you've noticed issues there. 45 is also linked to the MMU as the MMU will throw bus errors if the CPU tries to access memory it hasn't mapped. Could be the adder/comparator chips or the RAM used as MMU registers or something messing with their signals or operation (dust? board corruption from an old battery leak? short? bad filter cap on the RAM used as MMU regs?)
--- End quote ---
In what area of which board are there chips located? Are you talking about RAM on the RAM boards here, or is there RAM on other boards as well?
--- Quote ---Could also be RAM, but the RAM tests should catch that however.
I would remove all removable expansion slot cards, such as the SCSI board and trying to see if it goes away or not.
I'd clean the motherboard connector and the edge connectors on the I/O board, CPU board, and memory boards with a pink eraser, or DeOxit, etc and see if it goes away.
--- End quote ---
Expansion slot cards are removed! Taking out the SCSI adapter card was the first thing I tried.
I've been frequently applying contact cleaner (not Deoxit brand) to all edge connectors and sockets, but I can certainly try again to rub away oxidation from the edge connectors. In particular the edge connectors that lead from the Motherboard into the front of the machine aren't in great shape.
--- Quote ---If you happen to have spare boards to swap out and test that might help narrow down the issue.
--- End quote ---
Not at hand, but I know a local collector who has a battery damaged Lisa that he's been working on. Might try collaborating with him if I don't make headway by myself.
--- Quote ---I/O devices can also cause error 45 in time if they're not responding as that too triggers a bus error but it will take much longer if DTACK is not signaled in time as that inserts wait states before giving up.
If your I/O board has socketted VIAs you could swap VIA 1 with VIA 2 to see if the behavior changes, but most likely you would have seen other VIA related issues if it was them.
--- End quote ---
They are indeed socketed, but switching them out did not make a difference.
Anyhow, thanks for your suggestions! This is very helpful.
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