Editing Apple Floppy Disk Drive (section)

== Troubleshooting ==

Apple's symptom charts for the Apple 3.5 Drive family list cures in order of likelihood. If a replacement module does not cure the symptom, refit the original before trying the next cure.<ref name="ss35" />

{| class="wikitable styled-table" style="width:90%;"
|+'''Apple 3.5 Drive symptom charts'''<ref name="ss35" />
! Symptom !! Apple's sequence
|-
| Drive does not come on; LED flashes once or does not light || If an Apple 3.5 Drive 800K mechanical assembly is fitted as a Macintosh internal drive, verify the logic-board-to-drive cable is yellow, not red; then drive mechanism, external drive cable, LED assembly
|-
| Reads but does not write || Drive mechanism, then external drive cable
|-
| Does not read, but LED comes on || Check software, then drive mechanism
|-
| Does not eject disk || Drive mechanism, then eject switch cable assembly
|-
| Functions, but LED does not light || LED assembly, then drive mechanism
|-
| Ejects known-good system disks, but reads and writes after booting from another disk || Disk, then disk cable, then mechanical assembly
|-
| Reads and writes, but does not eject || Mechanical assembly
|-
| Internal 3.5-inch drive on a Macintosh Plus ejects continuously || Verify the cable has a yellow stripe, not a red stripe
|-
| Apple 3.5 drives daisy-chained to a DuoDisk or UniDisk 5.25 start to spin and can no longer be accessed by an Apple IIGS || Check the gate array on the daisy-chain interface board; replace a Revision A board (CXD1085A) with a Revision B board (CXD1085B)
|}

=== Cable stripe ===
An Apple 3.5 Drive 800K mechanical assembly used as a Macintosh internal drive needs a yellow-striped logic-board-to-drive cable. With a red-striped cable the drive may not come on, and an internal drive on a Macintosh Plus can eject continuously.<ref name="ss35" />

=== Daisy-chain gate array ===
When Apple 3.5 drives are chained to a DuoDisk or UniDisk 5.25 and suddenly spin up and become inaccessible from an [[Apple IIGS]], read the part number on the gate array on the daisy-chain interface board. CXD1085A marks a Revision A board; replace it with a Revision B board (CXD1085B).<ref name="ss35" />