General Category > Lisa Troubleshooting and Repair
Will the Lisa return an IO error without the "Lite" Interface Card
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:
--- Quote from: friedboard on August 28, 2025, 04:25:47 pm ---replaced the lite adapter but it's still the same. Do you know ...
--- End quote ---
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:
--- Quote from: friedboard on August 29, 2025, 09:54:27 pm ---the voltages from the power supply are correct...
--- End quote ---
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.
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