CAUTION! Improper tuning of the disk speed may cause your floppy to stop reading disks. Be sure that you have a spare working floppy so you can boot Locksmith from it.
Thing you will need:
1. Locksmith boot disk
2. Working floppy drive so you can boot from it
3. Blank 5.25 inch floppy disk or an old one that you don’t care for.
4. Flathead screwdriver for turning the motor speed trimer
5. Oil or lithium grease
6. 99% alcohol
If you recently acquired or have an old Apple II floppy drive that has been siting for years and does not read any disks, 70% of the times the drive mechanism is ceased and the head is dirty. In this tutorial we will show you how to clean, service and tune an old floppy drive. In our case we have a Bulgarian clone drive which is an exact copy of the original “DISK II” drive.
The first thing to do is to remove the screws at the bottom of the drive and pop-off the cover to reveal the internals. Inside you will find the main board of the drive, it is siting on four plastic poles on top of the disk rails. Be sure to remove the signal, control and head cables connected to the board. Then remove the plastic cap at the corner holding the board from sliding around (in some cases there might be two screws holding the board).
Removing the board reveals the drive mechanism, there is a large metal cap over the head mechanism that you need to remove. Remove any dust inside with compressed air and a brush. Then gently lift the top plastic part that presses the disk surface to the head and clean the head with 99% alcohol and a Q-tip.
The next thing is to lubricate the rails that the head mechanism rides on, you can use a drop of oil or some lithium grease which is the longer lasting option. Also, there is a plastic circle connected to the motor that drives the head mechanism. There you can see a small channel in which a ball bearing rides and therefore drives the mechanism back and forward. Be shure to dust off the channel and drop some oil, so that the bearing rides smoothly. Lastly gently run the mechanism by hand so that the lube spreads around.
The next step is to turn the drive over and remove the four screws holding the bottom metal plate. Remove and replace the belt if you need to. Then check the center axis which turns the disk, if it runs smoothly, leave it as is. But if you notice it grinding then you need to disassemble the axis by removing the front panel and then pull on both sides of the axis. Eventualy you will pop-off the top part and then the whole axis will slide out from the bearings so you can lubricate them with some oil. Lastly assemble everything back together.
Then reassemble the drive, put on the bottom cover, reinstall the main board and connect everything back together. Then you should be able to test the drive, but if it still does not work, you need to check the drive speed.
Connect your working drive as the first drive and your newly serviced drive as second, then boot up Locksmith and press “S” for adjusting drive speed. Then insert a blank disk in your drive. Select option “2” for optimal speed and then option “3” for coarse adjustment and select 3 samples. Then turn the trimer pot on the back of your floppy drive until the dots are located at the center line of the screen. Repeat the procedure for medium and fine tuning also until the dots are as centered as possible. Test your newly serviced drive and replace the cover. Then you have a completely serviced floppy drive for your Apple II.
After tuning you should have a completely working and serviced drive, ready to be used for many years to come.