General Category > Lisa Troubleshooting and Repair
Lisa Video, ProFile power issue, NiCad Leak fixes, etc.
AlexTheCat123:
--- Quote ---The Ready LED just indicates the state of the /PBsy pin. The controller does not provide any fault codes.
--- End quote ---
After looking at the ProFile schematic and the disassembly of the Z8 code yesterday, I started to realize that. I guess it's just trying and failing to read the spare table and the three flashes just happen to be the behavior of the /PBsy line in this situation.
--- Quote ---You can disconnect the controller cable and leave only the motor connected. Then move the step motor manually while the spindle is running. This should not require much force and should not generate unusual noises. Move it back to its parking position is at the outside, far away from the track zero sensor, before stopping the spindle.
--- End quote ---
I tried this and it seems to move fine without any resistance or weird noises.
I decided to probe the two ULN2074B chips that drive the stepper on the controller board and discovered that, while all four inputs to the the chips have activity on them when the ready light is flashing, only one of the four outputs going to the stepper has any activity on it. After swapping the two chips around, the single good output moved with the chip, so I'm guessing that one of the ULN2074s is completely dead and the other has only that one working output. I ordered new chips from Mouser that should be here on Monday or Tuesday, so hopefully that will fix the stepper problem.
rayarachelian:
--- Quote from: AlexTheCat123 on June 05, 2021, 11:09:56 am ---I decided to probe the two ULN2074B chips that drive the stepper on the controller board and discovered that, while all four inputs to the the chips have activity on them when the ready light is flashing, only one of the four outputs going to the stepper has any activity on it. After swapping the two chips around, the single good output moved with the chip, so I'm guessing that one of the ULN2074s is completely dead and the other has only that one working output. I ordered new chips from Mouser that should be here on Monday or Tuesday, so hopefully that will fix the stepper problem.
--- End quote ---
Oh sorry. But I'm very glad you can still find a replacement, and glad you've found it.
AlexTheCat123:
While waiting for those chips to come in the mail, I directed my attention to the ProFile's power supply. The fuse was blown and I'm assuming this happened because the hard drive drew too much current since it couldn't spin at all when the eBay seller turned it on to test it and they said that it powered on for a few seconds before the PSU died. I replaced it with a new one, connected the PSU to a load (a dead Macintosh SCSI hard drive since I didn't want to accidentally fry the ProFile if it didn't work), and it powered up just fine! All the voltage rails looked great, but around a minute later, one of the dreaded RIFA safety caps blew up, blew the fuse, and now the whole house smells terrible. I should have replaced those caps before even turning it on, but at least it's an easy fix. Using the original power supply will be much easier and cleaner than the horrendous setup I have right now with the ATX PSU.
rayarachelian:
--- Quote from: AlexTheCat123 on June 06, 2021, 07:53:56 am ---All the voltage rails looked great, but around a minute later, one of the dreaded RIFA safety caps blew up, blew the fuse, and now the whole house smells terrible. I should have replaced those caps before even turning it on, but at least it's an easy fix. Using the original power supply will be much easier and cleaner than the horrendous setup I have right now with the ATX PSU.
--- End quote ---
Ouch! Sorry.
I guess I should recap my ProFiles also. They've never been recapped, so those "RIFA The Destroyer" caps are likely due to pop. Thanks for the reminder.
AlexTheCat123:
Great news! I got the new ULN2074s for the ProFile in the mail today and after I installed them, the head stepper came to life and started performing the surface scan! The scan seemed to finish successfully and the ready light stayed on solid like it should. I plugged it into the Lisa and the ProFile came up under the "Startup From" menu, but it gave an error 84 when I tried to boot from it. This seems to mean that the boot blocks are damaged, so I'm assuming that I can just reformat it once I get the floppy drive working and then reinstall LOS and have everything working fine, right?
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