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Author Topic: Plan for Problematic Profile (+ some other word beginning with P)  (Read 331 times)

cheesestraws

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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?
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stepleton

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #1 on: March 04, 2021, 05:53:45 pm »

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...
« Last Edit: March 04, 2021, 05:56:00 pm by stepleton »
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cheesestraws

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #2 on: March 04, 2021, 06:11:52 pm »

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.
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rayarachelian

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #3 on: March 04, 2021, 06:23:57 pm »

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

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?
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stepleton

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #4 on: March 04, 2021, 06:32:41 pm »

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.)
« Last Edit: March 04, 2021, 06:37:15 pm by stepleton »
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cheesestraws

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #5 on: March 04, 2021, 06:46:32 pm »

It sounds more... abrasive than your NNNNNNNNNEEEEEEEEEEOOOOOOOOWWWWWWWWWWNNNNNNNNNN, but of course onomatopoeia is not a precise science.  Perhaps the best option is just to "run it in" for a while, see if the motor returns to its duty, and apologise profusely to the other half who shares the office with me.
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stepleton

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #6 on: March 04, 2021, 06:50:30 pm »

There may be little left to lose, but you may wish for a third opinion from someone who's less cavalier than I am about this (and who perhaps has a better idea of what you're dealing with). Good luck and I hope it doesn't throw a rod!
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rayarachelian

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #7 on: March 05, 2021, 11:31:47 am »

These might (or not) help:
If you do open it up, and probably that should be the last resort option, make sure you're in a room that has little dust. One thing you might do is bring it into a bathroom after running the shower for a bit to get all the dust to drop down to the floor, and then let the bathroom dry up a bit before you do open it.
You want neither high humidity nor dust. Running the shower should help get most of the dust in the air down, but the humidity isn't great either so wait for it to dissipate too. If your bathroom has a fan, use it.

Once you open it, if you see streaks on the media, that would indicate a head crash and would explain the high level of noise. Let's hope this hasn't happened.
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patrick

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #8 on: March 05, 2021, 02:52:07 pm »

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.

You can use an ST-412 as a direct replacement for the ProFile 5MB drive mechanism. Just replace the analog board, i.e. keep the one that came with your ProFile. ST-412 is the drive that was used with the IBM PC/AT, so it is fairly common.

An ST-506 mechanism will also work. However, Apple used their own stepper motor with a smaller step angle. With the stock motor, the ProFile would only access every other track. Therefore, you will need to disassemble the drive and install the old stepper motor. This requires a clean room area.

For the 10MB ProFile this is the only option -- you have to use a ST-412 together with the Apple stepper motor.


Concerning the bearing noise: Sometimes it helps to run the drive upside down for a while. This distributes the grease in the bearings. When upside down, the disk read heads must be on the parking track and must not be moved. To ensure this, you can disconnect the data cable from the disk and leave only the motor cable connected. Then cover the disk with a newspaper to keep it nice and warm, and let it run for a while.
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compu_85

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #9 on: March 08, 2021, 08:44:57 am »

...

You can use an ST-412 as a direct replacement for the ProFile 5MB drive mechanism. Just replace the analog board, i.e. keep the one that came with your ProFile. ST-412 is the drive that was used with the IBM PC/AT, so it is fairly common.

An ST-506 mechanism will also work. However, Apple used their own stepper motor with a smaller step angle. With the stock motor, the ProFile would only access every other track. Therefore, you will need to disassemble the drive and install the old stepper motor. This requires a clean room area.

For the 10MB ProFile this is the only option -- you have to use a ST-412 together with the Apple stepper motor.


I've fixed 4x 5Mb ProFiles with PC ST-506 mechanisms. I've not observed a stepping motor difference between the mechanism in the Profile and the PC drives. The 506 mechanisms I've used were produced from 1982 to 1984, so it doesn't seem like there's an early / late production difference. (The 1982 mechanisms had the mechanical spindle brake on them, instead of the electrical brake like the later drives!)

I've also fixed a 10M Profile with a PC-412, which worked properly. As a fiddle-fart test, running the 10m formatting software with a PC / Apple 5M disk fails when the stepper hits its end stop half way through.

That said, ST-412 disk mechanisms seem to be easier to find than 506s. I happened in to a box of "dead" 506, probably packed away in the late 80s. I'm guessing there was some fault in the Seagate PCB, because when fitting them to Profiles they worked fine.

-J
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cheesestraws

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Re: Plan for Problematic Profile (+ some other word beginning with P)
« Reply #10 on: March 11, 2021, 10:35:56 am »

Thanks for all your input, folks.  I really do think this drive is in dire mechanical straits, partly because I have to thump it quite hard to get it to start spinning at all.  Once I've got rid of the current drifts of chaos that surround my desk, I will probably try swapping the disc mechanism out.  Watch this space...
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