Turns out this is a useful diagnostic, as you can hear the difference between my faulty HD20 powering on and my working HD20 powering on.Could someone make a sound recording for me of what the HD 20 sounds like when it's not connected to a Mac and is then powered on, and then a second recording of what it sounds like when it is connected to a Mac, powered on, and the Mac boots from it?
Damn, this is just crazy stuff. So cool!So now, I have a perfectly working and mint looking HD20. I'm the happiest man on earth right now. I actually mended an old hard drive. I had previously tried to revive an old sony but that ended catastrophically...
Wow! How exactly did you clean it?Back in the very early 2000s I got my hands on an Intel server which had Quantum 4.3GB U320 drives in them that had all seized. Taking them apart revealed some type of "goo" the heads were sitting in, in the parked position.
Surprisingly I was able to clean up all the drives to the best of my ability and they all fired up and worked, Long enough to backup the data. and many many more years after that. Surprisingly. Culprit was a failed fan that cooled the drive chamber.
Can't rule it out. It's interesting to note that with a couple of these tracks with errors, that I've examined, it's usually just a handful of sectors that are unreadable, and the rest are fine. This is the Rodime 552 unit that I removed the lid from and watched its operation. I now regret doing that, as it served absolutely no purpose towards restoring the drive, and in fact may have made the problem worse by introducing dust or other contaminants.I wonder if its because of the platter itself loosing magnetic permeability. Thoughts?
Yeah, that's one of the many functions of HD Diag, and it's what I've done to restore a few tracks so far, but it's not working with every track. The Format_Track command lays down new headers on every sector of the track that is currently underneath the head. See Nisha Firmware Specification December 1984, page 32.This is is probably a dumb question and it may have even already been discussed in this thread, but is low-level formatting possible on the HD20? Because I know on MFM/RLL drives that is usually enough to bring them back to perfect health, unless they have physical platter surface damage like I mentioned above.
The data density is so low on these old drives that dust doesn’t even really bother them. I doubt that opening it even made a difference.This is the Rodime 552 unit that I removed the lid from and watched its operation. I now regret doing that, as it served absolutely no purpose towards restoring the drive, and in fact may have made the problem worse by introducing dust or other contaminants.
Cool!Yeah, that's one of the many functions of HD Diag, and it's what I've done to restore a few tracks so far, but it's not working with every track. The Format_Track command lays down new headers on every sector of the track that is currently underneath the head. See Nisha Firmware Specification December 1984, page 32.
Did you happen to make a detailed list of the electrolytic capacitors on the Rodime 552 controller PCB that should be replaced? (Capacitance, rated voltage, Diameter, Height & pin spacing (2.5mm?))As promised, here is Part 2 of my adventures in repairing the Hard Disk 20 (HD20). I show how to use HD Diag.