Editing Apple Design Keyboard (section)

== Controller and PCB Issues ==

=== Controller Chip Failures ===

{| class="wikitable" style="width:90%; text-align:center;"
|+'''Controller Diagnostics'''
! Symptom !! Test Method !! Likely Cause !! Repair Option
|-
| No ADB communication || Check voltage at chip || Dead controller || Replace keyboard
|-
| Random key outputs || Monitor ADB data || Corrupted firmware || No repair possible
|-
| Stuck keys || Test matrix scanning || Controller hang || Power cycle, check clock
|-
| Missing keys || Map matrix pattern || Bad I/O pin || Controller replacement
|}
[[File:AppleDesign Keyboard (NMB version) controller board.jpg|alt=AppleDesign Keyboard (NMB) Controller Board|thumb|307x307px|AppleDesign Keyboard (NMB) Controller Board]]

=== PCB Repair Techniques ===

'''Trace repair:'''
# Locate broken trace visually
# Scrape solder mask from trace ends
# Bridge with 30AWG wire
# Secure with hot glue
# Test continuity

'''Component replacement:'''
* Crystal oscillator: 6MHz standard
* Capacitors: Match values exactly
* Resistors: 1/4W carbon film typical
* ADB connector: Harvest from donor