Key Board Problem - Sam4s ER-430 SERIES Service Manual

8-5 Key Board Problem

Key Board Problem
Key Input
Failure ?
N
Specific Key
Failure?
N
Mode Key
Ok?
Y
End
SAM4S ER-430 SERIES
Y
Y
N
1. Check the Key Scan Part 74HC138(U27)
2. Check the Key Return Part 74HCT541(U2)
3. Check the related Circuit and Pattern
4. Check & Change Key Board Assy
5. Check the KBD Connector on PBA
1. Check the affected Key
2. Check the Matrix Bus & Data Bus
3. Check the Diodes(D22~D29)
4. Check the Key Board Assy
1. Check the Harness & Mode Key Assy
2. Check Diode (D18)
3. Check the 74HCT541 & Data Bus & CPU P10.3
8 Troubleshooting
8-5