400K Floppy Drives: Figured out how to de-gunk, but alas

[jsarchibald]

I have some 128k macs, but I can't get the floppy drives working at all.

Until Saturday, they were all gunked with 30 year old grease, and using some helpful tips here, I was able to figure out how to clean them and get them operating as they should (at least the insert/eject). Now, they are smooth as silk, which I am very happy about.

However, none of them will read a disk. I've cleaned a few 800K drives in the past, and have had a decent success rate getting them reading disks, but I've never adjusted one. All of these 400K drives accept a disk and spit it back out, but I know the alignment is out (disks need to go in at an angle, and don't slide out as expected - you need pliers to grab the disk and angle them out). The alingment is not off by much, but enough to cause a problem.

Secondly, even if the disk is in, they just won't read.

HELP! I have perfectly good 128K's that are afflicted with poor floppy drives!

 

[techknight]

Check your caps in the floppy drives for goo, that could seriously affect the head amplifier's ability to read/write the disk.

But if the actuator alignment is out, repair all mechanical grimlins first, then you can blindly adjust the stepper motor by loosening the locking screw and physically turning the motor. You can use this to get it back on track with a known good properly formatted floppy diskette.

 

[unity]

If you need a pliers then they are still gunned up. The actual mechanism for insertion and ejection can not be aligned. Remove the mechanical cage (pretty easy to do) and soak it in WD40 or the like. Then clean and re-grease. Only then would I re-align the heads.

As mentioned caps could be an issue. But I myself have never needed to re-cap a 400k drive. If you do, have fun. Lots of caps on the internal board around the speed motor. If you have the remove that board just tap on the underside where the motor is "pressed" in. Its soldered to the board but does lift out.

 

[Byrd]

My experience repairing 400K drives is that they're tough little devices, but when they're dead, they're dead, unless you have a scope or something to work out what is wrong with the electronics. My regime is to clean off the gunk, re-lube with sewing machine oil, and don't go near the electronics or heads apart from removing dust. If it doesn't work from cleaning it up (and most do), chances are the heads are mal-aligned, gears are mashed up/worn out and stripping down the drive is beyond the point of repair to me.

 

[bear]

Check the felt pad where the upper head would be if it were a double-sided drive. I've seen more than a couple where these had fallen out. It's also possible for them to wear to the point it goes out of conformance.