LisaList2
General Category => LisaList2 => Topic started by: dmark on May 07, 2022, 02:02:20 pm
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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 (https://tinkerdifferent.com/threads/lisa-2-repair-journey.1151/). 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 (https://vintageapple.org/lisainfo/apple-service-technical-procedures-lisa-macintosh-xl-ocr.pdf) 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!
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Has anyone in this community dealt with a fully deterministic Error 45 on your Lisa 2?
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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.
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.
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The Lisa 2 that I have on hand is one that ... I chronicled over at the TinkerDifferent forums (https://tinkerdifferent.com/threads/lisa-2-repair-journey.1151/).
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... I wonder if the heat and activity caused some component somewhere to degrade?
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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.
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?
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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.
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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?)
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?
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.
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.
If you happen to have spare boards to swap out and test that might help narrow down the issue.
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.
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.
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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Thanks for documenting the process of bringing your Lisa back to life; always an interesting adventure!
You're very welcome; thanks for reading it!
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.
I did replace the two large caps on the video board as a precaution, so that's done.
Do you have advice where good test points for each voltage rail is? I have it on my todo list to study the schematics to find out, but if you have suggestions off the top of your head that'll save me a little time. :)
If there is another Lisa owner in your neighbourhood, swapping parts about will probably help to localize the problem quickly.
As mentioned above, yes I do, although it is more heavily battery damaged than mine.
Do you have any test equipment beyond a multimeter?
I do have a digital scope! I was going to jump into looking at signals next...
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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.
How did you narrow down the root cause? Any particular signals I should try measuring?
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How did you narrow down the root cause? Any particular signals I should try measuring?
I started by checking the clock and reset signals on the 6504 microprocessor that controls the floppy drive to make sure that it was being properly clocked and reset, which it was. After that checked out, I probed all of the address and data lines between the 6504, its two 444C-3 RAM chips, and the I/O board ROM to make sure that there was activity on everything and that nothing was stuck high or low. I also checked a couple of the other signals feeding into the chips, like the R/W signals on the 6504 and the chip select signals on the RAM chips. By the way, you can find all of this stuff on the upper half of page 4 of the I/O board schematics.
When all of that looked good, I moved on to the bottom half of the schematic, particularly the circuity that generates /DTACK since I knew that the 68000 needs this signal in order to finish a bus cycle and will cause a bus error if it's never received. I didn't feel like going through all of the complicated flip flop stuff in the schematic, so I started at the end of the chain, just before the 8T97, to see if /DTACK was getting that far. It was, so I guessed that the 8T97 that buffers this signal to the processor might be the problem. I happened to have a spare 8T97 lying around from another project, so I figured that it would be quicker to swap it out than it would to take a deeper dive into what /DTACK was doing after it left the tri-state buffer and headed to the processor. And sure enough, that fixed my problem!
If you happen to have a chip tester of some kind, like the Retro Chip Tester Professional or the more limited TL866 programmer, you can save some time by throwing any suspicious chips in there to see if they're working properly instead of having to order replacements to see if the originals were faulty.
So clearly there was a lot of luck involved in my repair here (especially the part where I happened to have an 8T97, which in my experience isn't a very common chip, lying around), but hopefully you'll get lucky with your issue too!
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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?)
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?
They're 1Kx8 SRAMs on the CPU board.
see: https://lisaem.sunder.net/LisaSchem/CPU4.gif and https://lisaem.sunder.net/LisaSchem/CPU5.gif
They're around U8A, U9A, U10A They're the 214H8 SRAMs.
I'd also look at the adders at U8E, U9E, U10E - the F283s.
I'd also look at the latch at U4E.
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They're 1Kx8 SRAMs on the CPU board.
see: https://lisaem.sunder.net/LisaSchem/CPU4.gif and https://lisaem.sunder.net/LisaSchem/CPU5.gif
They're around U8A, U9A, U10A They're the 214H8 SRAMs.
I'd also look at the adders at U8E, U9E, U10E - the F283s.
I'd also look at the latch at U4E.
Sorry if this is an obvious question, but how do you test the CPU board in operation? Is there something like an extender board to run the computer with the card cage outside the case?
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Sorry if this is an obvious question, but how do you test the CPU board in operation? Is there something like an extender board to run the computer with the card cage outside the case?
There's no such extender board, sorry. You might be able to create one, but the length of the wires would be an issue. You could desolder those 3 SRAMs and test them and then resolder them back with sockets?
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Is it possible to get into Service Mode after an Error 45? If so, could you run some programs (or just do some memory reads and writes) to check whether the MMU registers are working as expected?
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Is it possible to get into Service Mode after an Error 45? If so, could you run some programs (or just do some memory reads and writes) to check whether the MMU registers are working as expected?
Yes, it is indeed possible to enter Service Mode from Error 45, inspect memory and run programs, run diagnostic tests etc! (TIL)
I'm not familiar with how to test the MMU registers on a Lisa, however. Do you have any pointers where I can read up on this?
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Yes, it is indeed possible to enter Service Mode from Error 45, inspect memory and run programs, run diagnostic tests etc! (TIL)
I'm not familiar with how to test the MMU registers on a Lisa, however. Do you have any pointers where I can read up on this?
I'd download a few versions of LisaTest and try those if you can boot at all. There's some way to go into the "Service Mode" advanced menu when it starts up and go into the individual tests.
Edit: looking at page 5.4 of http://bitsavers.org/pdf/apple/lisa/service/072-0085_Level_1_Lisa_Technical_Procedures_Mar85.pdf - it's the usual Apple-S to enter "Service Mode" in LisaTest as well as on the Boot ROM. D'oh! Surprised I forgot this factoid.
If you can't boot LisaTest, you could write some code to call the Boot ROM MMU routines, but that will be difficult to test unless you understand the Lisa's hardware and 68000 code. You'll need to write custom code, etc. As Tom mentions below there are a couple of routines to set/read the MMU registers.
There's also some code to do this in the ROM that you might be able to call - this might be harder if you do this with non "H" versions of the ROM as that's the only source we have for the Lisa Boot ROM, and earlier ones might not behave the same, etc.
But you'll have to play carefully with the MMU registers since any code you write will live in RAM and be invoked via service mode, and changing the MMU registers can cause that space (both the ROM routines and RAM you're writing code to) to disappear as it goes out of scope.
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Oh neat. Well, this would be a Project, but hopefully an interesting one.
Your first port of call is probably the Lisa Hardware Manual (https://lisa.sunder.net/LisaHardwareManual1983.pdf) and its description of how the MMU works (starting on PDF page 35).
Whatever code you make would have to ensure that the MMU is in the mode that allows you to write to the MMU registers. (This may already be the case in Service Mode --- I don't really remember.) Then you would write to the memory addresses where the MMU registers are and read them back to compare. Some care may be required since changing the MMU configuration may change whether you're still able to speak to the MMU in the first place.
Now for me there is nothing better than an example, and if you're similar, you'll want to check out the Lisa Boot ROM source code (http://bitsavers.org/pdf/apple/lisa/firmware/Lisa_Boot_ROM_Asm_Listing.TEXT) and see how it talks to the MMU.
You'd have to write your own code in assembly language, assemble it into hex data, and then type it into Service Mode and execute it and see what happens. You might use some of the utility routines in the Boot ROM to print out results (see the Boot ROM manual (http://bitsavers.org/pdf/apple/lisa/Lisa_Boot_ROM_Manual_V1.3_Feb84.pdf) PDF page 20 and page 28 onward), or you can just stash results in RAM somewhere and then inspect those memory locations with the Service Mode memory inspection tool.
(@Ray, it looks like LisaTest won't boot based on earlier posts... maybe still worth a shot to see if getting into individual test mode still works? I don't remember how to do it either.)
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Do you have advice where good test points for each voltage rail is?
I think this is still "current" ::) ...
https://lisafaq.sunder.net/lisafaq-hw-pwr_checking_voltages.html (https://lisafaq.sunder.net/lisafaq-hw-pwr_checking_voltages.html)
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Anyhow, grateful for any pointers how to further troubleshoot this poor Lisa!
An attempt was made ....
Debugging Bus Errors: https://lisalist2.com/index.php/topic,266.0.html (https://lisalist2.com/index.php/topic,266.0.html)
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how do you test the CPU board in operation? Is there something like an extender board to run the computer with the card cage outside the case?
There's no such extender board, sorry. You might be able to create one ...
General purpose off-the-shelf commercial extenders tend to be quite expensive, and you'd need two for the different sized connectors, so a home-made one is tempting.
An alternative to using an extender is to use the chassis wiring outside of a chassis; I've been using a home-made extender on the power/video connector for quite some time, and use a drive/keyboard cable removed from a chassis for the other connector (instead of a second extender). I think others have all the wiring outside of the chassis, but maybe that is only practical with an external monitor.
Since the signals in the Lisa are relatively 'slow' (ie. much less than 1 GHz) they tolerate a modest extension without difficulty. The fastest signal between the motherboard and chassis is the B&W video signal (~ 20 MHz) and since it is B&W it would have to degrade quite a lot before the video became unusable. On my extender I used coax for this one signal, the rest are plain wire (~ 18 AWG I think) between a (female) card edge socket and a veroboard with (male) card edge contacts. Extension length is about 8" (20 cm)
Now that one can get inexpensive boards produced in China, that may be a good way to go if someone has time to do the artwork. Perhaps there is enough interest to get some pre-orders here.
If you are tempted I would suggest:
- Make the extender in two pieces (one with 0.100" spacing, the other with 0.156" spacing), as the alignment of the two sizes of connectors is different in the Lisa 2/5 and 2/10
- Break out and mark the power supply voltages
- It may be helpful to have the possibility of headers on the floppy signal extender to connect drives behind the computer. For maximum utility one could have pads for two set of headers, one pair of 26 pins for the 2/5 and one 20, one 26 for the 2/10.
- Consider a potentiometer to reduce the speaker volume and (adjustable?) +12V power for a small fan that draws air through the PSU.
edit 1: Another advantage to using an extender is being able to adjust the PSU voltage in real-time with the actual load.
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Do you have advice where good test points for each voltage rail is?
I think this is still "current" ::) ...
https://lisafaq.sunder.net/lisafaq-hw-pwr_checking_voltages.html (https://lisafaq.sunder.net/lisafaq-hw-pwr_checking_voltages.html)
...nice one! (the joke, and the voltage measurement guide)
Now, the 5V rails look fine... But the 12V rails seem way out of whack on the I/O board. +7V and -17.5V respectively. :o
Which is weird, because before I measured a clean +12V on the Lite Adapter board, so I assumed that the same rail was ok elsewhere!
Just to make sure, I pulled out the Lite Adapter board again and measured on the floppy header, and am still getting a very neat +12V there.
So... at least I have a concrete issue to track down. It's almost as if 5V is being subtracted (or negative voltage added I guess) to the 12V rails!?
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Now, the 5V rails look fine... But the 12V rails seem way out of whack on the I/O board. +7V and -17.5V respectively. :o
Which is weird, because before I measured a clean +12V on the Lite Adapter board, so I assumed that the same rail was ok elsewhere!
Just to make sure, I pulled out the Lite Adapter board again and measured on the floppy header, and am still getting a very neat +12V there.
So... at least I have a concrete issue to track down. It's almost as if 5V is being subtracted (or negative voltage added I guess) to the 12V rails!?
Seems like the voltages are probably normal, but suspect one lead of your voltmeter is on the +5 rail instead of ground, perhaps due to an error in the FAQ instructions...
Double check that the ground lead is at ground potential, eg. the end of C47 nearer the edge of the board. If voltages are still wonky, try putting the ground lead on the chassis (voltages won't be as accurate but not off by 5V).
And check the lead connections at your meter aren't reversed (eg. red to common, black to V) ... this sometimes trips me up.
Good luck!
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Now, the 5V rails look fine... But the 12V rails seem way out of whack on the I/O board. +7V and -17.5V respectively. :o
Which is weird, because before I measured a clean +12V on the Lite Adapter board, so I assumed that the same rail was ok elsewhere!
Just to make sure, I pulled out the Lite Adapter board again and measured on the floppy header, and am still getting a very neat +12V there.
So... at least I have a concrete issue to track down. It's almost as if 5V is being subtracted (or negative voltage added I guess) to the 12V rails!?
Seems like the voltages are probably normal, but suspect one lead of your voltmeter is on the +5 rail instead of ground, perhaps due to an error in the FAQ instructions...
Double check that the ground lead is at ground potential, eg. the end of C47 nearer the edge of the board. If voltages are still wonky, try putting the ground lead on the chassis (voltages won't be as accurate but not off by 5V).
And check the lead connections at your meter aren't reversed (eg. red to common, black to V) ... this sometimes trips me up.
Good luck!
You're right, when measuring off the negative side of C47 I get -12V and +12.9V (the latter seems high!)
What tripped me up, and this may betray how little I know about electronics, is that I thought pin 119 (as well as 115) on the I/O edge connector socket was ground, because when I test continuity between that pin and ground (i.e. the chassis), I get a dead short. But now I do see the 5V on pin 119 under operation. How can this be?
Anyhow, lesson learned that testing continuity with the chassis when the machine is turned off is not a reliable way to identify ground.
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... when measuring off the negative side of C47 I get -12V and +12.9V (the latter seems high!)
What tripped me up, and this may betray how little I know about electronics, is that I thought pin 119 (as well as 115) on the I/O edge connector socket was ground, because when I test continuity between that pin and ground (i.e. the chassis), I get a dead short. But now I do see the 5V on pin 119 under operation. How can this be?
With tremedous thanks due to Al Kossow, the "original" Lisa schematics are available on Bitsavers.org, eg. the Lisa 1 or 2/5 I/O is at http://www.bitsavers.org/pdf/apple/lisa/hardware/050-4008-H_IO.pdf (http://www.bitsavers.org/pdf/apple/lisa/hardware/050-4008-H_IO.pdf)
Page 1 shows the card edge pinout, with pin 119 designated as /PWRSW, which will be tied to ground while the front panel power switch is pressed... possibly explaining your observation.
Pin 115 is +5V, which may show initially a low resistance to ground as there is a lot of capacitance that needs to be charged before reaching a steady state; after a few seconds of measuring resistance to ground, it should be more than a few ohms.
If you measure continuity using the "diode test" feature of a DMM (typically the feature that beeps when there is continuity), note that it can be misleading if one isn't paying sufficient attention to what you are measuring and how that feature works when not used to test diode junctions. Sometimes reversing the leads when using the diode test will quickly reveal that the connection isn't a direct one (since it beeps in one direction but not the other), but this may depend on the meter and circuit. Especially when troubleshooting mysteries, it may be preferable to stick with (or verify with) old fashioned resistance measurements, particularly when the difference between 1 ohm and 100 ohms makes a difference.
Your 12V supply may be a bit high due to minimal load on that rail. Since it is within 10% of 12V, it is probably fine.
+5V should be within +/- 5%, ie. 4.75V to 5.25V, so the power supply should be adjusted to that range.
HTH
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An alternative to using an extender is to use the chassis wiring outside of a chassis; I've been using a home-made extender on the power/video connector for quite some time, and use a drive/keyboard cable removed from a chassis for the other connector (instead of a second extender). I think others have all the wiring outside of the chassis, but maybe that is only practical with an external monitor.
Using a spare wiring harness, ribbon cable ( including the power switch/ KB jack assembly ), and external monitor is how I run the card cage outside the chassis for debugging.
Rick
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Using a spare wiring harness, ribbon cable ( including the power switch/ KB jack assembly ), and external monitor is how I run the card cage outside the chassis for debugging.
Rick
What model of monitor is that? Looks like a Conrac 38V44IOCA1?
https://www.ampronix.com/conrac-38v44ioca1-ivtm15a-15v44ioaap
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What model of monitor is that? Looks like a Conrac 38V44IOCA1?
Mine is a Conrac 38-V44IOA-A2. Be careful before you buy one, there were many variations of this model and not all versions will support Lisa's scan rate.
Here are the specs:
Industrial Series #V44 - 15
technical data
High Resolution Monochrome Monitor V44 - 15
(15" = 381mm)
Category Monochrome (CRT)
Format Cabinet (Metal)
Model V44 - 15"
Part Number 38-V44IOA-A2
Screen size 15" (381mm)
Max resolution 1000 TV lines center
800 TV lines corner
Phosphor P4 (white)
Horizontal frequency 15-40kHz
Vertical frequency range 45-90Hz
User controls Front: A/B Switch, Brightness, Contrast, H Position, H Size, Power, V Position, V Size, VTR Switch
Input voltage 100-240VAC 50-60Hz
Power consumption (max) 65W
On screen display No
Video connection BNC loopthrough, channel A/B
Dimensions (WxHxD) Inch: 15.8x11.7x16.6
mm: 400x298x421
Operating temperature 0-40°C
Weight 30.8lb/14.0kg
Warranty One year parts and labor
Approvals UL1950, CSA22.2 950, 89/336/EEC, FCC Class A, FDA CFR21, EN55022 Class A, EN60950
Options Rack Mounting Kit
Accessories AC Power Cord
Operators Manual
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Apologies all; inbetween catching Covid-19, and then trying to catch up on work after recovering, I haven't had much time for vintage computing projects.
I busted out the Lisa today just to see how she was doing. One new thing that I tried, which might be worth mentioning, is that when she boots with only one of two known good memory boards (tested both separately), she errors out at a different point during the boot process and with different errors. For instance, when loading Lisa Test 3 with only one memory board, the computer just hangs after about 1 min of reading from the floppy drive. No error 45.