Will the Lisa return an IO error without the "Lite" Interface Card

[friedboard]

Thank you!! It's just a generic multi-meter but I can certainly get a better one.
Trying to figure out where to start, would you happen to have the schematics of the IO board on a lisa 2/10?

[stepleton]

They are TIFF files, but you can find them here:
http://www.bitsavers.org/pdf/apple/lisa/hardware/Lisa_2_10_IO_Board/

(In general, bitsavers has all sorts of valuable documentation and is a good place to check if you are looking for anything like this.)

You can also find some reverse-engineered schematics here:

https://lisaem.sunder.net/LisaSchem/Lisa210SysIO1.gif
https://lisaem.sunder.net/LisaSchem/Lisa210SysIO2.gif
https://lisaem.sunder.net/LisaSchem/Lisa210SysIO3.gif
https://lisaem.sunder.net/LisaSchem/Lisa210SysIO4.gif
https://lisaem.sunder.net/LisaSchem/Lisa210SysIO5.gif

which I believe were made by someone or some people on this forum. They are easier to read than the paper scans of the Apple originals. Up until a few years ago, they were the only option the Lisa community had. But being made by a third party, there's a greater chance of encountering errors.

[friedboard]

Turns out it was indeed a dead hex bus driver SN74LS367AN. Replaced it and the Lisa is happily reading floppies again, thanks everyone!

What's strange though is that original floppy drive came with this Lisa is a 400k OA-D34V-2, not sure how it was paired with a Lisa 2/10 IO board