34 E8257D/67D, E8663D PSG Signal Generators Service Guide
Troubleshooting
Troubleshooting Assembly–Level Problems
If these signals are good, replace the LCD.
If these signals are not good, replace the power switch/flat panel interface
board.
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 37.
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:
J9−4 LCD_ENABLE_H >3 Vdc
J9−5 5.2 Vdc
J9−1, 2, 3, 8 to 15 Refer Figure 1-1 on page 33.
Signal State
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
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