issues with 5.25 drive on a IIgs

[lowlytech]

Forgive me I am not familiar with apple II troubleshooting at all.  I have a GS ROM1 that came with both a 3.5 and 5.25 drives.  When I connect both drives the 5.25 won't boot off of known good disks that work in my IIc, and it also makes the 3.5 drive get "stuck" where the drive access light will stay on, but the screen sticks at the bootup splash and you can't eject the 3.5 disk. If you disconnect the 5.25 from the 3.5, the 3.5 drive works great.  If you only hook the 5.25 drive up I still can't get it to boot despite it making the typical bootup seek sounds, but always get a check boot device message.  

Anyone run into this type of issue before.  Just thought I would check before blindly tearing into this 5.25 drive.

 

[DistantStar001]

I think the daisy chain on the IIgs requires the 5.25 to be connected first, then the 3.5 after that.

 

[Gorgonops]

Actually, the rule is the opposite of that. The chaining rules are:

IIgs > "native" 3.5" drives > SmartPort drives > 5.25"

If the drive doesn't work on its own it's almost certainly having a problem.

 

[DistantStar001]

Actually, the rule is the opposite of that. The chaining rules are:

IIgs > "native" 3.5" drives > SmartPort drives > 5.25"

If the drive doesn't work on its own it's almost certainly having a problem.

Just looked it up, and you're right.  Kinda weird, since I've been reversing it on my IIgs for years without a problem.  Then again, I don't have that many 3.5 in disks and even fewer that are IIgs specific, so maybe that's why I haven't run into a problem yet.

 

[DistantStar001]

After reading your post again, I would suggest connecting the drive to your //c.  Try booting from a DOS Master and cataloging a disk in the external drive to see if it reads.  If not then try cleaning the drive head, and see if that makes a difference.

The other thing I'll ask is, are your drives UniDisk or regular 5.25/3.5?  The internals of these respective drives are the same, but the analog/controller cards are very different.  My 5.25 is a UniDisk, but the 3.5 I use on my IIgs is just an 800k, and as I said I've had no problems reversing the order.  This was done not just out of ignorance, but also convenience since I often switch the 800k drive between different computers.  It's a long shot, but I have had issues with my 3.5 UniDisks playing nice with other computers, and drives.  Neither of them ever got along with my //c, and one stopped working out right when attached to my IIgs (it was the sole drive at the time).  The symptoms are almost exactly what you described from your 5.25.  

Since then, I've left the surviving 3.5 in Uni firmly attached to my //e, and I won't chain anything other than another 3.5 in Uni off of it.  My 5.25 has been better, but if you're mix and matching, it could be an issue.

 

[Gorgonops]

The internals of these respective drives are the same, but the analog/controller cards are very different

The 3.5" UniDisk is a magical and unique beast, but the "UniDisk" 5 1/4" drive is practically identical to the Platinum (vs. Beige) "Apple 5.25" drive that followed it, despite an erroneous warning that shows up on an A2 wiki website. Both drives are just a Disk II with passthrough functionality and are fully compatible with a IIgs. The only significant difference is the later drive doesn't require a -12v voltage feed, so it works with the Apple IIe card they made for Macintosh LCs.

I can't say why your 3.5" drive works when placed after the 5.25" in your setup. I've never tried it so I don't know if that advice from Apple is more of a guideline than a rule. The reason for it would be is the "native" 3.5" is the only drive that uses the 2mhz data rate of the IIgs' IWM, smartport devices (like the UniDisk 3.5) and 5.25" floppies use the 1mhz clock. They might have been concerned about signal degradation through the slower devices.

 

[lowlytech]

I took the 5.25 drive apart, didn't see anything obvious, I unplugged the bigger wire harnesses on the PCB and reattached and tested it while apart and it seems to boot fine now.  I don't know if I was dealing with a loose connection despite it looking fully attached, but preliminary results seem good.  I booted off 3 of the same 5.25 disks that wouldn't work last time I tried it and I can also boot from 3.5" when the 5.25 is connected.  The 5.25 and 3.5 drives are not the UniDisk variety.  The 5.25 is A9M0107, the 3.5 is A9M0106.

I will keep an eye on it, I really appreciate all the replies.  

 

[lowlytech]

spoke too soon, the minute I reassembled the drive and tested it, same no boot antics.  Must have a loose wire somewhere..

on the 3rd boot attempt, let the magic smoke out of the drive, I can't tell where it happened exactly, but the smell is strongest by the back connector (from external data cable).  Power supply was chirping, so something is shorted it appears.

 

[Gorgonops]

the 3rd boot attempt, let the magic smoke out of the drive

I did that to an already broken 5.25" drive once, I wonder if you made the same mistake I did. (I took it apart to try to reseat the head assembly, which had somehow jumped the guide track, but when I put it back together I didn't seat the circuit board into the case correctly, which caused it to short against the frame. IIgs survived but the drive was definitely kaput.)

 

[lowlytech]

Hooked it back up in pieces reluctantly after finding nothing damaged that I can see, and amazingly it still works, as long as it is apart.  Going to carefully put it all back together and try one last time.  The metal braid around by the base of the 19 pin cable looks a little ragged, wonder if something is shorting on that.   

 

[DistantStar001]

spoke too soon, the minute I reassembled the drive and tested it, same no boot antics.  Must have a loose wire somewhere..

on the 3rd boot attempt, let the magic smoke out of the drive, I can't tell where it happened exactly, but the smell is strongest by the back connector (from external data cable).  Power supply was chirping, so something is shorted it appears.

The 3.5" UniDisk is a magical and unique beast, but the "UniDisk" 5 1/4" drive is practically identical to the Platinum (vs. Beige) "Apple 5.25" drive that followed it, despite an erroneous warning that shows up on an A2 wiki website. Both drives are just a Disk II with passthrough functionality and are fully compatible with a IIgs. The only significant difference is the later drive doesn't require a -12v voltage feed, so it works with the Apple IIe card they made for Macintosh LCs.




1

I'd take it apart and check for a bad capacitor or exploded component.  While I've never had the need to take my 5.25 in Uni apart, I have successfully repaired several Disk II drives over the past few months.  If Gorgonops is correct, then there should be two boards in the drive, the first is the analog on top and a smaller one mounted to the back of the drive (given where you said the smoke was coming from, that latter would be my first guess).  If something did blow, then it should be pretty obvious when you look at the boards.  For a Disk II drive all the components are affordable, generic and very easy to replace.  Should the same should hold true for your drive as well, then it's definitely worth fixing.  If you're lucky (and have a soldering iron), then it shouldn't cost you more than a few Dolors, and about 20 minutes of your time.

 

[Gorgonops]

Gorgonops is correct, then there should be two boards in the drive, 

I don't remember if the one I took apart was a "Unidisk" or the newer one (when they're yellowed enough it's hard to tell them apart), but I believe both models use a single board. (There is practically nothing inside a Disk II because unlike a standard Shugart drive Apple drove the stepper motors directly from the controller.) The 3.5" drives *do* have separate drive and passthrough boards.

 

[lowlytech]

Your right, there are two boards on this floppy.  Haven't taken any component out to test, but I looked at all the traces and can't see any that burned.  The smoke was very faint, but unmistakable.   I almost am leaning toward two wires in the main cable touching there to cause the smoke.  I will try to hook an ohmmeter up and twist the cables around and see if I get any shorts.

 

[Gorgonops]

Your right, there are two boards on this floppy.

Doh, I stand corrected, technically there are. I didn't think of the one on the underside that only has transistors and whatnot on it, probably because I hadn't had to remove it for the mechanical work I attempted.

There's a thread on Applefritter that claims there's a drive transistor that likes to go bad on these drives, but I don't think that would cause repeated smoking...

 

[DistantStar001]

Haven't taken any component out to test, but I looked at all the traces and can't see any that burned.  The smoke was very faint, but unmistakable.   I almost am leaning toward two wires in the main cable touching there to cause the smoke.  I will try to hook an ohmmeter up and twist the cables around and see if I get any shorts.





1

Another suggestion would be to check your belts, as well as any area where the drive is supposed to physically move for signs of damage.  It also doesn't hurt to move these components around a little manually to make sure they're moving the way they're supposed to.  You said the drive worked when disassembled, so it's possible that the case is physically obstructing motion in the drive in some fashion.  If that happens, the timing might be thrown off, the disk might not spin, or the read head might get stuck, in any of these cases the drive won't read.  The smoke could be coming from friction between a free moving and obstructed components burning the belt or lubricant.  If this is the case, then all you need to do is find the obstruction, and clear it.  

Also, if it is the belt, then it might be a good idea to replace it, depending on the damage.

 

[lowlytech]

Got the drive back together and it works.  What may have been the issue was there was a cardboard type paper that I put back the way I found it, which was I believe on the wrong side.  This no doubt caused the shorted condition, smoke, and the drive just not wanting to read anything.  Keeping an eye on it, but I think for now it is good to go.