ST506 replacement in Profile

From: antiparallel <antiparallel_at_email.domain.hidden>
Date: Thu, 22 Mar 2007 23:13:07 -0700

First of all I should mention that this is my first post here. I want to thank you all for your efforts in keeping these wonderful and historically important machines alive.

I have recently acquired a 5MB Profile drive(A9M0005) but the ST506 mechanism is inoperative. The spindle doesn't spin when powered up, does not rotate freely when not powered, and makes a faint scraping sound when rotated manually - yikes!. The PCB support brackets have a slight but suspicious bend to them leading me to believe that this drive has experienced significant Gs - i.e., been dropped. The Profile's power supply checks out OK and the controller board and case appear in good condition. While the ST506 itself is probably unrepairable, I suspect that the rest of the Profile assembly is OK.

My first thought was to acquire another ST506 drive and transfer the Apple-branded PCB to the new drive if necessary. Unfortunately ST506s are pretty hard to find, with or without Apple PCBs. However, probably more ST412s (10MB) were produced as they were used in the early IBM PCs and the 10MB Profile drives and are possibly easier to find.

So I pose the following questions to this group hoping that someone here can illuminate my path:

  1. Am I correct in assuming that 10MB Profiles used ST412 drives?
  2. Are the Apple PCBs attached to the ST506 and the ST412 identical - i.e can I exchange the Apple PCB from my ST506 to a found ST412 from an IBM PC? I'm not talking about the Profile controller board, but rather the PCB actually attached to the drive mechanism.
  3. If I replace the existing ST506 drive with a ST412 (transferring the attached PCB in the process) will it work at all? ....will it only see 5MB of the 10MB drive?
  4. Is there any difference in the Profile controller cards in a 5MB Profile and a 10MB Profile? I suspect there are firmware differences at least.
  5. I don't recognize the 40-pin chip on the Profile controller card. What is it? Mine has a Signetic's logo and is labeled 341-0171-A. Is this a microcontroller? If so what family? The 341-number seems to be an Apple firmware designation.
  6. Should I just shut up and...
  7. hope to find a working profile on ebay someday?
  8. build a IDEFile from scratch? (I'm leaning towards this option)
  9. fork out the bucks for an X/Profile and don't lose anymore sleep?

Thank you for any insight, comments, or expertise.

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. Received on 2015-07-15 16:37:09

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