Agilent Technologies PSG Series Service Manual page 26

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
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
KEYCOL1
KEYCOL2
KEYCOL3
KEYCOL4
KEYCOL5
KEYCOL6
KEYCOL7
KEYROW0
KEYROW1
KEYROW2
KEYROW3
KEYROW4
KEYROW5
KEYROW6
KEYROW7
Table 1-11
KEYCOL0
KEYCOL1
KEYCOL2
KEYCOL3
KEYCOL4
KEYCOL5
KEYCOL6
KEYCOL7
KEYROW0
KEYROW1
KEYROW2
KEYROW3
KEYROW4
KEYROW5
KEYROW6
KEYROW7
Table1-10
P13-1
P13-3
P13-5
P13-7
P13-9
P13-11
P13-13
P13-15
P13-17
P13-19
P13-21
P13-23
P13-25
P13-26
P13-24
P13-22
P13-1
P13-3
P13-5
P13-7
P13-9
P13-11
P13-13
P13-15
P13-17
P13-19
P13-21
P13-23
P13-25
P13-26
P13-24
P13-22
Getting Started with Troubleshooting
to identify the appropriate pin number. The
Troubleshooting
1-13