Nokia 1508 Manual page 23

1508(RM-388)
Baseband Description and Troubleshooting
Keypad Faults (refer to Keypad circuitry)
First check if the keypad is well located: If not, locate it again or do the
•
replacement.
• Find out if there are faulty keys. Illustrated by the interface circuit of the Keypad,
except the PHONE-ON Key which is connected to the PMU Chip separately , all
the keys work in groups(R0 to R5 and C0 to C3) and each group use one CPU's
GPIO. Thus the faulty running GPIO can be located by confirming the faulty keys.
Further, short circuited signal or cold welding of the CPU should be modified or
replaced.
Issue 1
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