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1-15

Troubleshooting

Troubleshooting Assembly–Level Problems

Symptom: Hardkeys or softkeys do not work

The A1 Keyboard contains the hardkeys and softkeys switches. The keys are arranged in a matrix

(shown below) with the control lines KEYCOLx and KEYROWx on the x and y axis. When you press

a hardkey or softkey, one cell of the matrix is activated; the normally TTL low KEYROWx of the

active cell pulses high, and the normally TTL high KEYCOLx of the active cell pulses low.

1. Ensure that the front panel green power on LED is on. If it is not on, refer to “Power Supply

Troubleshooting” on page 1-17.

2. To ensure the signal generator is not being controlled remotely, press the

Local hardkey.

3. Use an oscilloscope to monitor the KEYCOLx and KEYROWx pins of the key that is not working

at P13 on the motherboard. Use the following table to identify the appropriate pin number:

4. If either signal is incorrect, use the following table and check the signal at P221, as it leaves the

CPU board. If the signal is bad at P221, replace the A18 CPU.

5. If both signals are correct, press the faulty hardkey or softkey while 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.

KEYCOL0 KEYCOL1 KEYCOL2 KEYCOL3 KEYCOL4 KEYCOL5 KEYCOL6 KEYCOL7

KEYROW0 softkey 3 N/A Cont Up N/A LF Out N/A I/Q Pulse

KEYROW1 softkey 2 Incr/Set Cont Down Ampl Ampl Menu Mode Setup Aux Fctn FM/ϕΜ

KEYROW2 softkey 1 Up N/A Freq Sweep List Mode Mux AM

KEYROW3 softkey 4 N/A N/A Right Arrow Help Save Recall Trigger

KEYROW4 softkey 6 N/A Local Hold Mod On/Off 4 5 6

KEYROW5 softkey 5 N/A Return Down Arrow N/A 7 8 9

KEYROW6 N/A N/A N/A Left Arrow RF On/Off 0 . +/-

KEYROW7 softkey 7 N/A Preset N/A N/A 1 2 3

KEYCOL pins should be a TTL high KEYROW pins should be a TTL low

KEYCOL0

P13

–1

KEYROW0

P13–17

KEYCOL1

P13

–3

KEYROW1

P13–19

KEYCOL2

P13

–5

KEYROW2

P13–21

KEYCOL3

P13

–7

KEYROW3

P13–23

KEYCOL4

P13

–9

KEYROW4

P13–25

KEYCOL5

P13

–11

KEYROW5

P13–26

KEYCOL6

P13

–13

KEYROW6

P13–24

KEYCOL7

P13

–15

KEYROW7

P13–22