CAUSE: 1. The hard disk/micro disk assembly fits snugly into the Mac XL's
cabinet. A number of screws terminate inside the disk assembly mounting
area. These two factors make it very easy to accidently damage the grey
flat cable or the drive power cable when sliding the disk drive assembly
into the XL.
2. A screw projects from the right of the main body of the Lisa
cabinet into the Disk Drive cavity. On some Lisas, this screw interferes
with a comfortable installation of the drive cage forcing the right rear
lip of a metal shield on the HDA down. This stresses the motherboard on
the HDA causing potentiometers on the HDA's PCB to misadjust.
CURE: 1. Replace the hard disk's grey flat cable. When reinstalling the
disk drive assembly, remove the XL's top to help you to guide the assembly
into its mounting place without damage.
2. Cut off the offending screw and if permanent visible damage
has occurred to the PCBs, replace the HDA.
If this cure does not resolve the problem, go to the Tech Procedures
to obtain a General Troubleshooting procedure.