Mac Plus floppy drive - help!

It's entirely possible that the eject mechanism still requires cleaning and re-lubricating. If the mechanism doesn't completely return to it's fully ejected position, the eject motor switch can be activated, making the motor go through another revolution.

Depending on how bad an environment the drive has been in the original lubrication can be badly caked onto the metal parts and needs to be completely removed. When I used to do these by the dozen, I would completely remove the top mechanism, the eject motor assembly, and the bottom sliding deck. You must remove the four split washers and the eject motor to remove the sliding deck. There can still be seized lubricant under the sliding deck and the underside of the eject motor has roller bearing that may need cleaning and lubricating. Once you've reconditioned these drives several times production line style they do get easier.

Also the eject motor uses a switch operated by a cam to turn the motor off once the fully ejected position is reached.

On the 800K drives there are two types.

One is the type used in the pictures on the page you linked to. They can be very delicate to disassemble, but it's not impossible.

Look at the top of the drive. You see a small green circuit board in front of the eject motor. The board is held in by a couple of plastic clips at the edge. Release the clips and CAREFULLY lift the circuit board straight up. DO NOT LIFT IT AT AN ANGLE.

On the underside of the board you'll see the two parts of the switch. A long flexible part that is moved by the cam, and a short fixed part that the other touches to close the circuit. Cleaning the surfaces where they meet with emery paper might be required. Refitting the PCB is a little fiddly. Note that the switch parts must fit into narrow slots on the plastic housing and the switch must be open slightly to avoid being crushed by the cam.

The other type has a micro switch with a white actuator that is operated by a cam on the top. These don't tend to be as prone to failure but anything's possible. The pic above is poor quality but the site below with a better pic seems to be down ATM.

The eject motor gearbox can also be a culprit, though it is rare. There is a short guide here (site seems to be down ATM)

daniel-b said:

...My drive seems to be the second type. Here are some pictures. Obviously it is possible I put it back together wrong, but mechanically everything looks OK when I insert and remove a disk...

I assume this is the microswitch...

Click to expand...

Correct. To remove the eject motor, undo the two screws and the plug noted in the first pic below. Remember, there is a roller bearing on the underside of the eject motor assembly that may need cleaning and re-lubricating. Sometimes the gearbox needs cleaning and re-lubricating. There are three screws on the underside of the eject motor assembly that allows access to the gears.

Also, some drives from poor environments end up with head motor worm drive bearings partially seized. In the second pic, apply a little oil to the two bearings on either end of the worm drive shaft as noted.

Sometimes it is necessary to remove the head assembly and clean the smooth shaft and guide hole. This probably shouldn't be lubricated when re-assembled. In the third pic, the shaft placement is in yellow. Remove the two head cables carefully by pulling straight up. then remove the screw at the end of the shaft. Clean the shaft and the two holes in the head assembly that it feeds through and re-assemble.

These are all the steps in both this post and my previous one (as well as the guide you linked to) that I would perform (required or not) when reconditioning a 800K or 1.44MB floppy drive. Then I would test them. If they didn't pass they were pretty much scrap. Obviously, cleaning the heads is a must.

daniel-b said:

Thanks again for the extremely detailed instructions.

Just one more question: Is alcohol on a q-tip OK for cleaning the heads?

I'll let you know how it goes.

Daniel

Click to expand...

Yes, but there are some difficulties. As noted in the guide you linked to, you MUST NOT spread the heads apart. Doing so will stretch the top head pressure spring, ruining the drive. Also, the heads are mounted on a piece of metal with slots cut in them. Applying too much pressure, can bend this slotted plate that the head is mounted. Adding to that, fibers from the q-tip can get caught in the slotted plate, bending the plate when you withdraw the q-tip and/or remaining behind and fouling the disk and head.

I ended up using a long floppy drive cable, a head cleaning diskette, a program called "TechTool" v1.2.1 which had a 'head exercising' option (actually a floppy drive head cleaning option. For stubborn marks on the heads I would use a little pressure on the top head whilst running the head exercise on a cleaning diskette with a drop or two of alcohol or other cleaning agent.

I also forgot about one other common failure. The write protect, disk insert and HD detect switches often become faulty or intermittent. These are the little white posts on the very front edge of the drive. Usually, a little bit of compressed air into the switch followed by a tiny squirt of harsh contact cleaner (RP7, CRC-26 etc) would get them working but sometimes I needed to grab a spare from one of those scrapped drives I mentioned in my previous post.

daniel-b said:

I opened up the eject motor gearbox, and found little bits of plastic in it.

Removing one of the cogs revealed this:.....

Time for a new drive, right?

Click to expand...

Yup, but perhaps only for a new eject motor assembly? IE, a transplant!

EDIT: You could leave the eject motor out, and use the manual eject at the front of the drive. I'm pretty sure the drive should behave since it has a "disk inserted" detect switch at the front. Just practice with a strong paper clip before fitting the drive to get a feel for how much force is needed to eject a disk.

daniel-b said:

One more question: I have an external HDI-20 floppy drive. I don't suppose that the drive from that would work in the Plus, would it?

Tks,

Daniel

Click to expand...

Not easily. I suspect the signals are interchangeable, but the cabling certainly isn't. Nor would it be easy to adapt the cabling. Mounting would also not be easy. The connector on the drive is a flat flex type.

I just looked on eBay... These drives are getting pricey. Maybe I should get the old production line going again!

You should be able to get a eject motor assembly from a 1.44MB Sony Mac drive, Model MP-F75W-01G (Apple exchange P/N 661-0474). This would mean almost anything up to and including "Mac LC" or "LC II" and most MacII series machines (IIci IIcx IIvx). Basically, if it doesn't have a black flap in the floppy drive slot, you could use the drive for parts.

Of course, all this depends on if you can get YOUR drive to read/write properly, which you should be able to test as I noted before.

EDIT: The 800K drive should only have two switches. Write Protect & "Disc Inserted". The 1.44MB drive has three switches.

daniel-b said:

I opened up the eject motor gearbox, and found little bits of plastic in it.

Removing one of the cogs revealed this:

Image

Time for a new drive, right?

Click to expand...

Just to cross-reference, there is a source for these gears on shapeways:

https://forums.macrumors.com/posts/20524803/