Floppy Drive - Wisdom needed.

[smrieck511]

I have a 1.44mb Drive from an SE FDHD that is acting strangely (I also have a spare 800k that I could take some parts from). I'm pretty familiar with tearing the drives down and yes, the cheese cog has been replaced.

Symptoms -

The GOOD:
- Eject mechanics are working perfecto...Drive is lubed and gear has been replaced.

The STRANGE:
- Fails trying to format an 800k disk UNLESS I format it to One Side first and then format it to Two Sided. In this way, it DOES reliably format 800k disks.

- 1.44 Disks either get the "Needs Minor Repairs" error and on repair attempt fails and ejects.

- OR Ask to Initialize the disk at which point, everything appears to go well. The drive writes up the disk but when the head comes back down to Verify, I get the Verification Failed error and the disk ejects. Every time.

And advice is greatly appreciated.

 

[Mk.558]

Has it been recapped?

Old media? Even the newest of the "goodish" lot towards the end of the bell-curve of production is close to 20 years old.

Copy II Mac has a disk sector reader. Comparing it to a known sector readout can probably tell you if the heads aren't aligned properly. If the heads have ever been even slightly budged out of position, they won't read correctly.

Any other machines you can test the drive itself in, or swap drives around? Test the disks with other machines?

The power supply on the SE has been recapped, through and through, with voltage levels OK?

Going to poke around to see if there's still diagnostic disks around that can be used with special software (or an oscilloscope) to check alignment. In the former days we'd just chuck it into a bin and forget about the whole affair as we replaced it with newer one, but it's 2025 and times have changed.

 

[smrieck511]

Yeah floppy drive has been recapped, Power supply recapped 12 and 5v a ok...I have several SE/30's and SE's and these disks work in my other drives so I know I've isolated the issue to this specific drive.

I just tried this....

- Took a 1.44mb disk and put a piece of tape over it to trick the drive into thinking it was an 800k disk.
- Formatted one side to 400k ...good
- Formatted two sides to 800k ...good
- Took the tape off and the drive asked to format it correctly to 1.44mb...Formatting goes well but as soon as the head starts to ride back while verifying, the disk is ejected and I get an Initialization failed error.

 

[Mk.558]

Well I appreciate you starting this thread as you sent me down a rabbit hole of looking at this issue. Looks bleak because nobody makes floppy alignment disks anymore, and I can't blame them. Even finding one is difficult because if people bought one, they bought it for a 5.25" or 8" drive, which I have on good authority is not involved in your case. And, just because you have it, doesn't mean it's succumbed to mold or mildew or plain decay, which, guess what? You can't duplicate them.

I'll report back in a few hours or days, something. In the meantime I'd recommend checking out Copy II Mac. I don't know how it'll work in your case, but use it on a known working machine to get a feel for it. Use the manual on Macintosh Garden, the one on my site is slightly older version of the manual.

 

[s_pupp]

Try zero-track adjustment: https://68kmla.org/bb/index.php?threads/bad-head-alignment-on-800k-floppy-drive.47517/#post-533342

It has worked for me in similar circumstances, but I have a few drives right now that I could not get to work properly at all. I suspect a bad optical sensor, since the boards, mechanics, stepper motor, and read/write heads all work when placed into another drive.

 

[bibilit]

Hi, are you sure the SE is really a FDHD ? and has the appropriate ROMS and SWIM ?

The Logic Board could have been swapped at some point with the former LB, here the information with the newer chips

original chip replace with

342-0352-A HI ROM 342-0701 HI ROM
342-0353-A LO ROM 342-0702 LO ROM
344-0043-A IWM 344-0062-01 SWM

Another option is that the SWIM chip can be bad at some point.

 

[smrieck511]

Yeah, definitely an FDHD. Interesting that I don't think I'm seeing the same numbers but I did just format a 1.44mb disk with a known working drive to make sure I'm not going crazy.

 

[Mk.558]

The zero track sensor is probably the best lead to follow. I haven't been able to find any resources for diagnostic purposes for Macs, as all the stuff is primarily designed for 5.25" disks.

There is a chance a wizard of a programmer can make up a new program designed to work with the 128K forwards that can use special digital diagnostic disks, but they'd have to be made on a different machine and a real floppy drive is not the same thing as a real alignment disk.

 

[smrieck511]

Try zero-track adjustment: https://68kmla.org/bb/index.php?threads/bad-head-alignment-on-800k-floppy-drive.47517/#post-533342

It has worked for me in similar circumstances, but I have a few drives right now that I could not get to work properly at all. I suspect a bad optical sensor, since the boards, mechanics, stepper motor, and read/write heads all work when placed into another drive.

Thanks so much. I'm going to read the pdf and learn about this.

 

[Fred1212]

Yes track zero alignment will be the problem. Loosen the screw holding the motor just enough to get some rotational movement and then rotate the motor Really small amount in one direction test and if no go try the other direction. I've done a number of these and sometimes you get it straight away and others you need to move the motor all the way to the LHS and back to the RHS in lots of very small steps. Also you need to power off and back on again every increment and with others I've found you can just push a disk after each increment and it works. Good luck

 

[s_pupp]

Yes track zero alignment will be the problem. Loosen the screw holding the motor just enough to get some rotational movement and then rotate the motor Really small amount in one direction test and if no go try the other direction. I've done a number of these and sometimes you get it straight away and others you need to move the motor all the way to the LHS and back to the RHS in lots of very small steps. Also you need to power off and back on again every increment and with others I've found you can just push a disk after each increment and it works. Good luck

Powering off is a very good idea. A slip of the screwdriver recently caused a spark, and, thinking back, was likely the cause of the blown floppy drive Bourns filter I had recently.