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Author Topic: Profile sticking at Track 0  (Read 168 times)

blusnowkitty

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Profile sticking at Track 0
« on: October 19, 2021, 01:12:00 am »

Splintering off the Lisa Software List thread again, let's see if I can figure out why one of my Profile disks quit working!

So yeah, I was trying to copy off Art Department to one of my physical Profile disks and it appears some component responsible for head positioning failed mid-copy which caused that huge cascading failure that trashed all my other disks too.

Got to playing with BLU and like my mostly-working disk, when I install the LLF ROM I see the stepper behaving as normal - as in, if it's not sitting on Track 0, it'll step the head back to Track 0 no problem. If I tell BLU to read the metadata track, it reads it no problem! But when I  tell it to start a low level format, it pretty much instantly fails at Status 4000000. Installing the normal mask Z8 back in and here's where something weird happens - initially, it was taking around 30 seconds to read each sector during the startup self-test. Now, it shuffles the head from beginning of disk to end of disk a couple times, and then heads back to Track 0 and stays there - it never tries to leave Track 0.

So now I'm curious, what happens if I try to move the heads manually while the disk is spinning? Here's something else interesting: Whenever the head goes back to Track 0 and stays there, on either ROM, something is keeping the stepper energized and will not physically let me move the head while power is on. I can overpower the motor if I push on it hard enough but I'm sure that'll damage something if I keep that up... And if I do overpower it, the motor still stays energized and doesn't try to rotate back to Track 0. This persists whether or not the Track 0 sensor is actually connected to the ST-506 or not. Out of curiosity I disconnected the Track 0 sensor from my mostly-working disk and it managed to pass self-test no problem. I wonder if  that's why that disk likes to crash against the head stop so often?

It's late for me as I'm writing this and I have to work in the morning so no playing with a DMM or a scope for me tonight - but has anyone else seen any similar issues with their disks?

For reference tomorrow: https://www.applefritter.com/content/profile-hd-schematics
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compu_85

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Re: Profile sticking at Track 0
« Reply #1 on: October 19, 2021, 07:09:51 am »

If you disconnect the stepper and power the spindle motor, does the stepper rotate freely? No grease divots?
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AlexTheCat123

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Re: Profile sticking at Track 0
« Reply #2 on: October 19, 2021, 10:46:38 am »

Whenever I try to LLF my ProFiles with BLU, I get similar failure messages a lot for no apparent reason, but USBWidEx and the ArduinoFile device that I'm currently designing can format the drives just fine. If you have a USBWidEx, maybe try formatting with it instead. Maybe this could be some sort of bug in BLU or something?
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blusnowkitty

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Re: Profile sticking at Track 0
« Reply #3 on: October 19, 2021, 05:27:51 pm »

If you disconnect the stepper and power the spindle motor, does the stepper rotate freely? No grease divots?

Well I'll try it powered but disconnected, but when unpowered it moves freely and again, even doing its reseek to Track 0 the head moves as freely as it does my semi-working disk.

Whenever I try to LLF my ProFiles with BLU, I get similar failure messages a lot for no apparent reason, but USBWidEx and the ArduinoFile device that I'm currently designing can format the drives just fine. If you have a USBWidEx, maybe try formatting with it instead. Maybe this could be some sort of bug in BLU or something?
I don't think BLU is to blame here. Something's keeping the stepper energized at Track 0 whether the disk is connected to a Lisa (and I'd assume WidEx/ArduinoFile) or not. The fault seems to be entirely localized in the Profile itself.
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compu_85

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Re: Profile sticking at Track 0
« Reply #4 on: October 20, 2021, 05:39:55 pm »

I once had a one of the output gates stick on a SA400 floppy disk. The drive would kind of seek, but it sounded really off and didn't work properly. Eventually the gate in the driver chip stuck on completely and started burning the current limiting resistors!

As the drive steps you should see the outputs cycle in sequence. I'm not exactly sure how the circuit in the Profile works, but I can dig into one later tonight.

-J
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