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Good afternoon (for me),

 

I decided to write this thread apart from the other one about this device because I don't want to divert the attention from the main thread.

So to put you in situation, I have a Macintosh Plus with an Apple 20SC HD that originally came with a 20MB MiniScribe drive. I love the sound of that hard drive and I'm looking to get it back. The original drive has mechanical problems and stopped working many years ago, but I thought the logic board was working.

 

This drives are surprisingly expensive nowadays, so I found this one on Ebay and thought that maybe I could swap the boards and get a working device. I think this one was for an Apple II.

 

https://www.ebay.com/itm/Miniscribe-Apple-20mb-Disco-Duro-Modelo-8425-Usado-Garantía/202583301784?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

Thing is it's not working. When I switch it on it initiates normally and then the stepper motor starts to make a click-click noise, like forwards-backwards movement for a minute or so and then stops. It took for ever to format it using Silverlining, but eventually I was able to write and execute applications from the drive, so it kinda works. Only it takes more time than normal to initiate due to this click-click thing and it won't mount automatically, I have to do it with Silverlining, so I can't boot from it.

 

Question one will be asking for help or tips on how to troubleshoot the unit as I have it now. I scanned for bad sectors with Silverlining and it said it had 1 error, providing no further information. I'll try with Norton Utilities when I get home and see if it does any better.

 

Question two will be if is it possible to rewire the Apple II drive board to SCSI. Looking at both boards doesn't seem to have much in common, just a couple chips are the same, so I don't know if that would be possible. Of course I tested the unit when I got it and it didn't make that noise, so I assume I have a bad board.

 

The (I think so) Apple II device board that came with the device:

IMG_6272.thumb.jpg.545eda89e1e517d1db220fef50b94469.jpg

The SCSI board from my first device:

IMG_6271.thumb.jpg.41bd326b439ae24dd329e634f3d46285.jpg

 

The click-click noise:

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Have you tried oiling the stepper motor? Its also possible it has a bad read/write head. 

 

More importantly, you need a tool to low-level format the SCSI drive using a SCSI bus call. That might help too. 

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It's odd, I've tried low formatting with FWB hard disk toolkit, it gives me an error (not specified). Quick format works fine and no bad sectors found, and once mounted it works just fine, I can write and run apps from there, and everything works normally. It's just when the drive initializes, which is when it's switched on or prepared for being formatted when the odd clicking appears. For some reason quick formatting and driver update works OK, but low formatting or Apple's SC Utility fails during the clicking part.

 

The stepper motor works fine, because the drives behave normally once it's mounted and because my old drive does exactly the same clicking noise. Of course that one won't do anything else, as it has bad plates, but the initializing sounds are the same.

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Try the Micronet utility. We need something that the drive performs the low-level format, and not the software itself. Think of a firmware syscall. I am not at home right now so i cant listen to the physical sound. 

 

But Miniscribe drives are supposed to sweep the stepper motor back and forth at least once, and then begin to hunt for the negative cylinder just before cylinder/track 0. this contains the formatting and geometry information. Then it moves on. This information is highly specific to the controller that formatted the drive. the low level formatting is also specific to the controller. 

 

if any of those tracks are unreadable for any reason, the drive's firmware will continue to hunt over and over for that track until it reads it error free. 

 

If the error is caused by a magnetism issue, Only a low level format will fix this. If its not a magnetic issue, then either the cylinder is damaged on the platter, or the head is bad and in either of those cases there isnt much you can do. 

 

The only way to rule anything out is a true low level format issued from a proper SCSI command to the drive itself. 

Edited by techknight

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On 7/15/2020 at 11:47 AM, techknight said:

Try the Micronet utility. We need something that the drive performs the low-level format, and not the software itself. Think of a firmware syscall. I am not at home right now so i cant listen to the physical sound. 

 

But Miniscribe drives are supposed to sweep the stepper motor back and forth at least once, and then begin to hunt for the negative cylinder just before cylinder/track 0. this contains the formatting and geometry information. Then it moves on. This information is highly specific to the controller that formatted the drive. the low level formatting is also specific to the controller. 

 

if any of those tracks are unreadable for any reason, the drive's firmware will continue to hunt over and over for that track until it reads it error free. 

 

If the error is caused by a magnetism issue, Only a low level format will fix this. If its not a magnetic issue, then either the cylinder is damaged on the platter, or the head is bad and in either of those cases there isnt much you can do. 

 

The only way to rule anything out is a true low level format issued from a proper SCSI command to the drive itself. 

Last night I tried a few things and none worked. With Silverlining or FWB at least I could get it mounted, but every formatting option with Micronet led me to an error. Low-level format seemed to work OK all the process until at the end it got stuck on the click-click sector. I'll give it another try this afternoon, but I have low expectations.

 

When you say a firmware syscall do you mean Micronet?

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Then that click-click sector is a bad sector. It needs to be mapped in the bad table. Not sure how you can do that with Mac software, but I know you can do that with PC software. Once all known bad cylinders are stored in the preformatted bad table, that blocks them off from OS tools being able to use it. Then the drive will skip over that sector every time. 

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Alright, I could test the drive using Micronet and found out one bad sector (9569), but using Micronet to reallocate it leads to the clicking noise and a couple of errors. I think I'm done here. :`-(

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