[comp.sys.apple] Apple Tech Notes: Using Duodisks on the //gs

ranger@ecsvax.UUCP (Rick N. Fincher) (12/15/86)

Using the DuoDisk with the Apple IIGS
The DuoDisk can not be used as the last daisy chained device on the 
built-in IWM disk port of the Apple IIGS. For instance, a UniDisk 3.5 
will be rendered inoperable when the DuoDisk is installed in the above 
manner - although using the DuoDisk by itself is not a problem.
A qualified technician will have to modify the DuoDisk analog 
board if the DuoDisk is to be used as the last device on the 
chain. Please use the following procedure to determine how to 
modify the analog board.

IDENTIFYING WHICH ANALOG BOARD YOU HAVE
Remove the top cover as documented in Technical Procedures. Turn 
the drive so that the I/O connector is facing toward you. The 
identifying number will be at the bottom left of the analog 
board. The number might read 676-[]101, 676-[]102 or 676-[]107.

PERFORMING THE MODIFICATION

If the I.D.# for the analog board is 676-[]101 or  676-[]102, use 
a pair of nippers and cut out resistor R8 (located at position 
A2).
If the I.D.# for the analog board is 676-[]107, use a pair of 
nippers and cut out resistor R39 (located at position A1).
Compliments: 
Apple Service Training