General Category > Lisa Troubleshooting and Repair

Plan for Problematic Profile (+ some other word beginning with P)

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cheesestraws:
Opinions, folks:

I have a 5MB profile here that is extremely unwell, in that it only spins up one time in two, and when it does so, it makes the most appalling grinding and shrieking and scraping noises and I think has difficulty holding a consistent speed.  So that's the HDA assembly gone, then.  But I think the controller board and PSU are fine; it appears to do all the self-tests and does the right thing according to the manual.  And the Lisa will recognise it as a profile, but doesn't like it: I can't blame it, I don't like it much either.

So, I have options as to what to do with this:

1. Leave it as it is as a piece of set dressing / future cheesestraws' problem.  This seems a waste and is rather against my general philosophy.
2. Stick a solid-state thing in.  But this would essentially just be putting modern hardware in the profile case, and in some ways seems even more of a waste given that the controller board looks like it's fine and so does the PSU.
3. Try to find a working ST506/ST412 (?) and try to do surgery on it to put the Apple board on the bottom of it.  I currently have no idea how to do this, nor how to do the required low level formatting when it is done.

What do people think is a good plan here?  What have people had success with in the past?

stepleton:
2. I have my IDEfile in a case for a broken (but in retrospect probably it was once fixable with the knowledge I have today) ProFile --- there's a picture of it on the IDEfile FAQ. I kinda like it, though.

3. I think you would just substitute the Apple-designed board on the bottom of the drive mechanism for the MFM board that comes with an ordinary '506. But then you would indeed have to low-level format the drive. For that you need to replace the ProFile controller board Z8 microcontroller with a new microcontroller that has the "formatter" ROM code installed. I might be able to help out a bit here --- I have some surplus Z8s that accept a "piggyback" ROM chip, intended for general circulation within the Lisa community, though I don't have the ROM chip itself.

Once the chip is installed, I think BLU can format a ProFile.

Regarding the loud noise, have you seen the Apple Lisa FAQ entry about silencing louder ProFiles? Maybe yours can be improved...

cheesestraws:
Thanks for the information and the offer of help.  I'm leaning towards (3) at the moment, but I'm going to think on it for a while.  It is good to know that a "vanilla" 506 will work with a swapped circuit board.

Unfortunately, this isn't so much a "loud jet engine" sound as an "angle grinder attacking aluminium and varying in rotational speed" kind of sound redolent of imminent and messy mechanical failure.  Think of exactly the noise you'd want not to come out of a motorised device, put it up an octave, and that's what it sounds like.

rayarachelian:

--- Quote from: stepleton on March 04, 2021, 05:53:45 pm ---Regarding the loud noise, have you seen the Apple Lisa FAQ entry about silencing louder ProFiles? Maybe yours can be improved...

--- End quote ---

That silencing bit is about getting moving the static discharge clip. I think his may have a mechanical issue. Possibly motor isn't getting up to speed?The bit about leaving it powered on for 3 days might help if the grease is frozen, but maybe at this point it might need new grease?

But, where do we get that from? And what viscosity would you need?

stepleton:
I might have heard a serenade like that before, but I'm not sure. There are two kinds of really unpleasant not-a-jet-engine ProFile noises I'm familiar with. One is the "wobbly squeal" sound that you can hear in that ProFile video I linked to yesterday, at about 5:24. The other one I know is a very loud "NNNNNNNNNEEEEEEEEEEOOOOOOOOWWWWWWWWWWNNNNNNNNNN" kind of sound that sends the mind drifting toward thoughts of bearings.

I've known my ProFiles to make these noises occasionally for about 24 years now :)
They seem to go away with use, and then they come back sometimes and go away again... For now I think of them as "character", and whenever they crop up again I generally just let the offending drive have its noisy time and hope that it settles back down after a while.

It's worked so far. That said, I'm sure the Bad Day will come at some point as it does for any mechanical thing. There's a reason why one of my big hobby projects is a hard drive emulator... although I'll sure try hard to keep these things running as long as I can, and these days I keep them on a programme of occasional exercise to try to keep things loose.

(Now, I've never encountered a ProFile that seemed to lose RPMs before. I have seen it in a Widget that I was investigating, and... you guessed it, eventually the syndrome passed and it got better. I was so anxious at the time that the motor circutry was taking a beating, but it turned out okay. This time.)

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