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[friedboard]

Thank you again for the detailed analysis! I checked my motherboard and it is indeed a 620-0108-E which only has an external parallel port.
I seem to have a stock lite adapter with no modifications at all

The weird part is that my floppy drive was working just fine with floppyemu before the esprofile incident. I was able to load up Lisa 2 diagnostics, macworks 2 and boot to macos just fine.
I plan to replace the 8T97 first to see if that will make a difference as it seem to hang with error 23 after the initial 57 on boot. (only with floppy emu)

[sigma7]

The weird part is that my floppy drive was working just fine with floppyemu

I have a vague recollection of someone mentioning this phenomenon before, so there are clearly some holes in my logic/understanding/memory.

I presume the FloppyEMU works in that case because it does not need the motor speed signal. AFAIK, it can determine the virtual speed based on the track number, and I suppose it doesn't need to vary anything at all in that regard, since the change in RPM is only to make the flux change density on the magnetic media more consistent, so the digital rate remains the same regardless.

Now I wonder if there are further consequences, such as:

• is it the case or my imagination (or hallucination -- I promise that I'm not AI) that the superdrive doesn't use the motor speed signal? If so, will it work in this configuration even though 400K and 800K drives don't? (Don't try it if you don't know... maybe the wiring isn't compatible in some way)
• does the same effect mean that a 1/5 I/O Board will work with a FloppyEMU and 2/10 motherboard and chassis cabling?

[friedboard]

What is strange is that it came from eBay this way and I assume the machine must have been in a working state before and not modified after. It has a "Lisa is now Macintosh XL" sticker in front, H/88 ROM and a switch to toggle screen height (I assume to work with MacOS and Lisa OS)
Even though the original drive is stuck it was plugged into the lite adapter and the red light works

[friedboard]

Here is a picture of the IO board

[friedboard]

Part of the motherboard

[sigma7]

it came from eBay this way and I assume the machine must have been in a working state

It is certainly possible that I'm wrong that it shouldn't work (or maybe there are more specifics as to where it does and doesn't)... can someone else comment on this:

Does a mechanical 400k/800k floppy drive work in an otherwise normal 2/5, except with a 2/10 I/O Board installed?

edit: from a brief experiment, it seems an 800k drive will work, while a 400k drive does not.

[friedboard]

I actually think you are right! But this might not be a 2/10 IO board, but a 2/5 board. Just not the common version that we see

[stepleton]

I actually think you are right! But this might not be a 2/10 IO board, but a 2/5 board. Just not the common version that we see

I'm pretty sure this is a 2/10 I/O board. 820-4033-A, the IWM chip up at the top left corner --- it's just like the one in my 2/10.

[sigma7]

But this might not be a 2/10 IO board, but a 2/5 board. Just not the common version that we see

Although it isn't impossible that new boards will be found, I don't think this is one... here is the schematic for the 2/10 I/O Board for verification: http://bitsavers.org/pdf/apple/lisa/hardware/Lisa_2_10_IO_Board/

[sigma7]

It is certainly possible that I'm wrong that it shouldn't work (or maybe there are more specifics as to where it does and doesn't)...

I've now done some superficial testing and found that I was mostly incorrect.

In summary, the 2/10 I/O Board in an otherwise stock 2/5 does appears to work with Sony 800K drives, but doesn't work with a 400K drive.

With a Sony double sided drive, after swapping in the 2/10 I/O Board, the drive did seem to run normally and the floppy was readable (since this was a very superficial test, there could be more subtle issues such as slow performance, or not). I tested an MPF75W and MPF51W.

With a 400K single sided drive, after swapping in the 2/10 I/O Board, the drive did clearly misbehave; the motor would run, but not at the usual speed, or with the usual variations, and the disk was not readable. Upon swapping the Lite Adapter for the modified version described in the LisaFAQ http://lisafaq.sunder.net/lisafaq-hw-io_substitution.html, the 400K drive worked again.

I expect any Floppy Emulator won't need the motor speed signal, so would work like the Sony drives.

I didn't test any off-brand drives, such as the Chinon drive sold by Sun Remarketing for a while.

Apologies for the misdirection; I'll correct my previous post on this topic.

[friedboard]

Just replaced 8T97 and error 57 went away with floppyemu but still will not read any disks. It doesn't even attempt to read and will go back to the insert floppy message.
Will try to replace the whole lite adapter next

[friedboard]

replaced the lite adapter but it's still the same. Do you know what U5B-13 is on the Lisa 2/10 board?

[sigma7]

replaced the lite adapter but it's still the same. Do you know ...

Tracing those signals to the 2/10 I/O Board:

Phi A comes from U2F-3.

/WREQ comes from U1C-13.

RData goes to U1C-2.

Sense goes to U3F-5.

MT1 comes from U9A-3.

It is possible that there is some other problem that won't be repaired by replacing all the parts, so some troubleshooting may be more expedient... do you have any test equipment (DMM, Logic Probe, Oscilloscope, voltmeter, etc.)?

[friedboard]

Yeah, I think all the voltages from the power supply are correct and the boards pass basic startup and extended tests so that is a good sign! I believe what is broken might be a chip specifically for reading floppies

[sigma7]

the voltages from the power supply are correct...

I take that as indicating you have some kind of voltmeter.

If you watch the DC voltage at each of the signals listed while inserting a floppy disk, you might observe some activity. Which ones are active and which ones are not may reveal the point of failure (or more likely, suggest further measurements to make to better localize/determine the failure... troubleshooting is an iterative process.)

ie. connect the voltmeter to a signal (and the other lead to ground); insert a floppy while watching the voltage to see if it fluctuates, as well as the average reading, record your observations, eject the floppy, repeat with each of the other signals. Then report what you've observed and further suggestions can be made.

It will be useful to know what kind of voltmeter you have since different voltmeters respond differently to fluctuating signals.