Key Board Problem - Sam4s ER-280 SERIES Service Manual

5-5 Key Board Problem

Key Board Problem
Key Input
Failure ?
N
Specific Key
Failure?
N
Mode Key
Ok?
Y
End
SAM4S ER-280 SERIES
Y
Y
N
1. Check the Key Scan Part 74HC138(U19)
2. Check the Key Return part 74HCT541(U21)
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(BAT43WS *7EA)
4. Check the Key Board Assy
1. Check the Mode Key Assy
2. Check the Diode (D19)
3. Check the 74HC138(U19) & Data Bus
5. Troubleshooting
5-5