Keysight Technologies E8257D Service Manual page 35

Troubleshooting
Troubleshooting Assembly–Level Problems
4. If either signal is incorrect, use the following table and check the signal at
5. If both signals are correct, press the faulty hardkey or softkey while
E8257D/67D, E8663D PSG Signal Generators Service Guide
P221, as it leaves the CPU board. If the signal is bad at P221, replace the
A18 CPU.
KEYCOL pins should be a TTL high
KEYCOL0 P13–1
KEYCOL1 P13–3
KEYCOL2 P13–5
KEYCOL3 P13–7
KEYCOL4 P13–9
KEYCOL5 P13–11
KEYCOL6 P13–13
KEYCOL7 P13–15
monitoring the KEYCOL or KEYROW on the oscilloscope. The KEYCOL line
should pulse low; the KEYROW line should pulse high.
If either line does not function properly, replace the front panel board.
KEYROW pins should be a TTL low
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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