Floppy Hassles

In my life I have opened at least 40 Amiga 500's and have NEVER seen two which have the same make and model of internal floppy. It seems that Commodore change their suppliers (and also the colors of the LEDs on the keyboard) on a weekly basis. Let's see.. three possible LED colors (red, green, yellow), three LEDs on the keyboard, four floppy manufacturers (Sankyo, Chinon, Panasonic, Sony), two different styles of head connector (one film connector per head or one wide film connector servicing both heads), helical screw or belt-drive head carriage mechanisms.. that makes 144 possible configurations already. For this reason it is not possible to give specific "look-to-the-left- of-the-large-chip" directions, and I can only state a couple of possible faults and their possible causes : _ _* Floppy refuses to acknowledge disk insert _Probably caused by a defective odd CIA (U7). Try switching the CIAs over. Also check that the switches at the front of the drive travel freely up and down. Verify that the pads to which the switch assembly is connected have not flaked off the board (this can be caused by rough disk insertion). _ _* Floppy will not read disks formatted in other drives. The head alignment is faulty. There is a method of adjusting it without special tools and measurement devices, but it requires considerable patience and one of the X-Copy series of programs. 

The method is as follows : _- Format a disk in a working drive. _- Open your machine (or external drive). Remove the cover from the drive unit (it is usually held on by one screw on either side and another on top at the back). Locate the track zero sensor and loosen the screw which holds it in position. Load X-Copy and select the Toolkit option CHECKDISK. _- You must now align the lower head. This can be accomplished by moving the track zero sensor a little, then checking the disk, and repeating this until you find a position in which the drive will read the lower side of the disk. When this is done, tighten the screw which holds the track zero sensor, to stop it shifting. If you have any Lok-Tite, a drop of that on the screw is advisable. _- You must now align the upper head. Loosen the two screws which hold it to the head carriage assembly (Do NOT remove these screws, unless you relish the idea of going over the floor with a metal detector looking for small springs). Adjust the upper head by eye until it appears to be exactly over the lower head. Now repeat the above trial-and-error process, tweaking the upper head around until you find a workable position. Tighten the screws, replace the cover and reassemble. _ If the above procedure sounds rigmarolish and uncertain, it is ! But I have successfully performed it on a number of Amiga and PC 3.5" drives. And I have never had a failure with it. _