Troubleshooting Mac SE/30 Floppy Drive Functionality

[joseph]

My primary goal is to have a working internal high density floppy drive "SuperDrive" on a Macintosh SE/30. I'd appreciate any thoughts about my situation.

I received two 3.5" DSHD (FDHD) floppy drives, both Sony MP-F75W-01G floppy drives. One came out of the very SE/30 I'm working with. They were filthy and non-working and that prompted me to perform cleaning, re-greasing, and recapping (Console5 kits). It turned out that both floppy drives' original capacitor values measured mostly okay, and also the original worm mechanism gears were fine. I took some notes about the process.

Both drives do NOT read or initialize 3.5" DD or HD media in the SE/30 running System 6.0.8 or 7.5.5 with a 32-bit clean ROM (if the software environment makes any difference).

The Mac SE/30 I'm working with was formerly simasimac and was professionally repaired and tested by a service. The memory and ROM are new. It's running off of a plain Pico-based BlueSCSI. These are just notes, there's been no other issues with the computer.

The floppy disk media I'm working with fully functions (initializes, reads, and writes) in an external Apple 3.5 Drive (A9M0106) on the same Mac. The external drive will recognize and format my DD and HD disk media just fine. I thought this was only a DD drive, but HD seems to also work when on this controller. If I put these same disks in either Sony MP-F75W-01G, the computer prompts that it needs to initialize them. After running through that process it says that the disk is bad and ejects it. Putting that same disk back in the external drive shows it hasn't been touched and that there are still valid files and programs. There's truly no read or write happening on these Sony drives. I have tried two different floppy cables.

I read some posts on here about the UH7 SWIM chip. But if that component were bad, I think that the external drive also would not work? Adding a 2pF capacitor to the PCB as an experiment made no difference.

I took some videos of the Sony drives:

• Drive 1
• Drive 2 has an added mechanical skip

On eBay the external drives seem to be much cheaper than internal ones. Would parting out an external work as compatible substitute? I don't want to take apart the working external I already have.

I'll see about finding another Mac that takes FDHD to also try these in if that would help narrow things or not.

Would it help to find or buy a third auto inject drive to compare against these two?

 

[Boctor]

Is the zero-track position on drive 1 properly aligned? Not exactly a trivial question, but I only ask because it was the issue for 3 in every 4 auto-injecting drives I've cleaned, and seems to be a common problem.

 

[bibilit]

Have you tried connecting the external drive directly to the internal cable for a test ?

 

[joseph]

Is the zero-track position on drive 1 properly aligned? Not exactly a trivial question, but I only ask because it was the issue for 3 in every 4 auto-injecting drives I've cleaned, and seems to be a common problem.

It now certainly isn't because that I've fiddled with it. This looks daunting. Is there some other instrumentation I can use to help with this calibration? I notice the gate goes to 4.8V when the plastic passes through it.

The ZTA document linked on TinkerDifferent is asking for a mechanical skill that might be beyond my abilities. I'm supposed to tighten down a piece of plastic, with 0.5 mm of travel, that has a 0.035mm tolerance? Are there any ideas about making a jig or some assisting piece for this? I can't really see the dot I made.

Have you tried connecting the external drive directly to the internal cable for a test ?

I just tried your suggestion and it worked! It was also another MP-F75W-01G inside of there. So I have three of these drives and one works; the external which is internal at the moment.

 

[bibilit]

Bad heads or head not clamping enough the disk.

Are the heads clean ? Can you swap heads (from one not working drive to another)

 

[joseph]

There is more head travel on drive 1 and it might not be clamping down enough. What's a good way to adjust that?

I made a video comparing the head travel on the drives. There's clearly a difference and drive 3 (the external) is tighter.

I've cotton swabbed the heads with IPA if that is sufficient to call them cleaned.

I hesitate to dissemble the working drive and swapping head parts around. I understand that would help with a process of elimination, but I'm not confident about placing it all back together working again. There's variable assembly like zero track sensor, head clamping, head alignment and I'm not sure yet what doing that correctly would look and feel like. I will try to find a second working drive so that I have some room for these experiments.

 

[Byrd]

On eBay the external drives seem to be much cheaper than internal ones. Would parting out an external work as compatible substitute? I don't want to take apart the working external I already have.

It's the exact same drive in the external case, and straightforward to take apart (screws at bottom, lift off plastic housing, cable, remove shielding), there is your working internal test drive