Troubleshooting
Getting Started with Troubleshooting
1-13
If a front panel hardkey or softkey is not functioning, use an oscilloscope to monitor the KEYCOLx and
KEYROWx pins at P13 on the A31 Motherboard. Use Table1-10 to identify the appropriate pin number. The
KEYROW pin should be a TTL low and the KEYCOL pin should be a TTL high. If either signal is incorrect,
use Table1-11 and check the signal at P221 as it leaves the A18 CPU. If the signal is bad at P221, then replace
the A18 CPU. If both signals are correct, then press the faulty hardkey or softkey while monitoring the
KEYCOL or KEYROW on the oscilloscope. The KEYCOL line should pulse low, while the KEYROW line
should pulse high. If either line is not functioning properly then replace the A1 Keyboard.
Table 1-10
KEYCOL0 P13-1
KEYCOL1 P13-3
KEYCOL2 P13-5
KEYCOL3 P13-7
KEYCOL4 P13-9
KEYCOL5 P13-11
KEYCOL6 P13-13
KEYCOL7 P13-15
KEYROW0 P13-17
KEYROW1 P13-19
KEYROW2 P13-21
KEYROW3 P13-23
KEYROW4 P13-25
KEYROW5 P13-26
KEYROW6 P13-24
KEYROW7 P13-22
Table 1-11
KEYCOL0 P13-1
KEYCOL1 P13-3
KEYCOL2 P13-5
KEYCOL3 P13-7
KEYCOL4 P13-9
KEYCOL5 P13-11
KEYCOL6 P13-13
KEYCOL7 P13-15
KEYROW0 P13-17
KEYROW1 P13-19
KEYROW2 P13-21
KEYROW3 P13-23
KEYROW4 P13-25
KEYROW5 P13-26
KEYROW6 P13-24
KEYROW7 P13-22
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