Troubleshooting a DuoDisk unit

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Troubleshooting a DuoDisk unit

I'm working through a problem with the second drive in my DuoDisk unit.  Specifically, it spins up, but the head doesn't read the disk.

This leads me to suspect two possible culprits:  the read head or the stepper motor.

 

Is there any troubleshooting tips?  Any way I can rule out the stepper motor at least?

I take it back.  I didn't realize it, but the characteristic chatter when a disk drive starts is the stepper motor.  So presumably it's fine.  That leaves the read head...

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It may not be the head at all

It may not be the head at all, it could be an electronic problem on the analog board.

 

 

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softwarejanitor wrote:

It may not be the head at all, it could be an electronic problem on the analog board.

 

I had considered that.  But, I tested both disk drives as Drive 1.  One boots ProDos from disk just fine, the other does not.  So it seems apparent to me it's an issue with the disk drive.

That left me with two possible culprits - either the stepper motor or the head (or possibly the wiring from the head...)  Since the stepper motor chatters on startup, it leaves me to think it's almost certainly the head.  Of course, that occurred to me only *after* I  posted here.  <sigh>

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joel_graff wrote:

It may not be the head at all, it could be an electronic problem on the analog board.

 

I had considered that.  But, I tested both disk drives as Drive 1.  One boots ProDos from disk just fine, the other does not.  So it seems apparent to me it's an issue with the disk drive.

That left me with two possible culprits - either the stepper motor or the head (or possibly the wiring from the head...)  Since the stepper motor chatters on startup, it leaves me to think it's almost certainly the head.  Of course, that occurred to me only *after* I  posted here.  <sigh>

 

Have you checked the drive speed?  If that is even slightly off it can cause failure to read.

 

 

 

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softwarejanitor wrote:

Have you checked the drive speed?  If that is even slightly off it can cause failure to read.

 

I calibrated both drives visually - I don't have the disk diagnostics software at the moment.

 

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Disk Speed

If you have Prodos 2.4.2 from the Diskserver site, go into Copy II Plus, then choose "Verify", and you will see a Disk Speed option in there.  Then you just insert a blank disk or a disk you don't care to lose data from and run the Speed test from C2Plus and can get a decent read from it.  There are also AppleCillian and MECC COmputer Inspector programs from the disk server site as well you can use.

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joel_graff wrote:

Have you checked the drive speed?  If that is even slightly off it can cause failure to read.

 

I calibrated both drives visually - I don't have the disk diagnostics software at the moment.

 

 

Unless you've got a timing light of some kind that probably isn't accurate enough.  You need the software to do it right.

 

 

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softwarejanitor wrote:

Unless you've got a timing light of some kind that probably isn't accurate enough.  You need the software to do it right.

 

A little update.. I did stumble upon the drive speed test in CopyII plus.

 

On my good drive, it told me I was at 199.5 ms (the range is 198 - 202).  The second drive just gave me garbage numbers at first.  I shut it off and poked around at the head assembly a bit, though I didn't really do anything.  When I tried it again, the seond drive started reading 200 ms on the speed test!

 

Anyway, looks like both drives are speed calibrated.  It seems eye-ballin' it is worth something, anyway. :)

 

Then I went on to test the disk integrity.  Drive 2 failed on every track and sector.  The disk is good, so although the drive is now reporting properly on the speed test, it still isn't right.

 

I'm worried it may be a loose wire connecting the head to the board.  Those are really small wires.  Don't know that I can fix that.

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