Sync Sensor Installation

Many copy protected programs for the Apple II series relied on floppy disk tracks that were specially aligned to each other. This was not something that could easily be replicated with consumer floppy drives, but required specialized disk copier equipment. This made it much harder to copy. The Applesauce sync sensor enables your regular Disk II floppy drive to gather the rotational position of a floppy disk in order to capture these aligned tracks.

This document details the installation process of the sensor. Installation of the sensor does not modify the functionality or compatibility of your floppy drive with original Apple II computers. It simply adds an additional sensor and cable that allows for the gathering of the sync information. If you are not looking to image copy protected disks, then you do not need to install the sync sensor to use Applesauce.

What you need for this installation

The installation of the sync sensor is straightforward, but there are several steps to the process. You will need a Philips screwdriver #2, scissors or wire cutters, isopropyl alcohol and some cotton swabs. You may also need a large flat head screwdriver.

The sync sensor kit comes with 3 components. The sync sensor, cable and an adhesive-backed magnetic strip.

Opening the case

You need to remove the 4 screws under the drive to remove the outer shell of the case.


Remove the drive base

Remove the ribbon cable from the drive. You will need to press the little latch to unhook the cable from the case bottom. Then unplug the 20-pin connector and remove the assembly.


Flip the drive on its side and remove the 4 screws underneath.


Figure out which drive casting you have

Some of the early Shugart drives have a different casting that doesn’t allow for the sync sensor to be installed into the underside of the drive. If yours looks like the picture below, then you will need to do a top-side sync sensor mounting. Also, if you have any issues with the install, you should use the top-side method as well. To perform the top-side mounting, the magnet will be adhered to the underside of the collet shaft receptacle. You will need some additional 2-sided mounting tape to raise up the sync sensor in order to fit properly.

Remove the drive belt

Slip the drive belt off of the spindle.

Clean the mounting areas

Before adhering the parts to the inside of the drive, you need to make sure that the surfaces are clean. It is best to use isopropyl alcohol on cotton swabs to do this. You need to clean the underside of the wheel. Spin the wheel with one hand while cleaning. You also need to clean the area below the wheel where the sync sensor will mount.


Mounting the magnet

Cut a small square from the end of the strip of magnet included with the kit.


Pull the backing off of the tiny square you just cut and mount the magnet to the underside of the wheel. It should have an edge lined up exactly with the edge of the wheel. It should not protrude past the edge of the wheel.

Now, make sure that the wheel spins freely 360 degrees. The magnet should not rub anywhere. If it is rubbing, then you can place a flathead screwdriver between the wheel and the frame and very gently pry the wheel upwards just until the wheel spins freely.

Mounting the sensor

First, you will want to put the sensor in place just to measure how tall it should be. It will need to be bent in order to properly face the magnet as well as fit under it.

Once you know approximately how tall it should be, you will need to use some pliers to help bend it into the correct shape.


Then, test fit the sensor underneath the magnet. It should not touch the magnet, but there should be as little space between the sensor and magnet. The black head on the end of the sensor needs to be as perfectly lined up under the magnet as possible. It should also be lined up pointing at the center of the wheel as much as possible.

When you know where you are going to place the sensor, remove the paper from the adhesive strip on the underside of the sync sensor. Carefully install the sync sensor into the correct position. Once you press it down, it will be stuck really well, so try not to mess it up. After you have it in place, you can tweak the position of the sync sensor head to make sure that it is still good relative to the magnet.

Install the cable

You next want to get the cable and fish it through the hole in the frame as shown in these pictures. You then want to carefully plug the cable into the sync sensor.

Replace the motor belt

You should now place the belt back onto the wheel. It is easiest if you install it on the smaller end first and then rotate the wheel as you place the belt on it.

Reinstall the drive frame into case

You are now ready to put the case back on. Put the bottom on first and install the cable. Be sure to orient the cable correctly and then double-check it.

Now would be a great time to plug the drive into your Applesauce and start up the software. It you go to the Tools page, you can do a Drive Speed test to make sure that the sync sensor is functioning properly. Once everything seems to be working ok, you can finish putting the case back on the drive.