Installation guide

Troubleshooting
Getting Started with Troubleshooting
1-15
Symptom: If Hardkeys or Softkeys are Not Functioning
The A1 Keyboard contains the switches for the hardkeys and softkeys. These hardkeys and softkeys are
arranged in a matrix, as shown in Table 1-9, with the control lines KEYCOLx and KEYROWy on the x and
y-axis. When a hardkey or softkey is pressed, one cell of the matrix is activated. The normally TTL low
KEYROWy, of the active cell, will pulse high and the normally TTL high KEYCOLx, of the active cell, will
pulse low. These TTL signals may be measured with an oscilloscope at J32 on the A23 Motherboard. Use
Table 1-9 for hardkey and softkey matrix locations.
Figure 1-8 J30 and J32 of the A23 Motherboard
❏ Ensure that the signal generator is powered-on, that the front panel green LED is lit, and that the signal
generator is not being controlled remotely.
— If the signal generator is powered-on and the green LED is lit:
a. Press the Local hardkey to place the signal generator in local-control mode.
b. Press any suspected defective hardkeys or softkeys while monitoring their corresponding KEYCOLx
and KEYROWy line at J32 of the A23 Motherboard.
— If either signal is incorrect, refer to the Table 1-10 and check the signal at J15
on the A23 Motherboard.
J15 is where the signal leaves the A12 CPU.
— If the signal is incorrect at J15, replace the A12 CPU.
(Refer to “A12 CPU” on page 2-30.)
— If both signals at the J32 and J15 connectors are correct, replace the A1 Keyboard.
(Refer to “A1 Keyboard” on page 2-8.)
— If the signal generator is powered-on and the green LED is not lit,
refer to “Power Supplies” on page 1-23.