Installation guide

Troubleshooting
Getting Started with Troubleshooting
1-17
Symptom: If the RPG Knob is Not Functioning
When the RPG Knob is functioning properly, DS11 on the A12 CPU should blink each time that the RPG knob
is rotated.
Figure 1-10 Blinking of DS11 Indicates RPG Knob Activity
• Ensure that the signal generator is powered-on and that the front panel green LED is lit.
— If the green LED is lit and the RPG knob is not functioning:
a. Check J32-12 for +5.2 VD_LCD.
— If the voltage is present on J32-12:
a. Press the Frequency hardkey on the front panel.
b. Using an oscilloscope, monitor J32-14 and J32-10 while rotating the RPG knob.
The display frequency value should change and both signals at J32-14 and J32-10 should
pulse to a TTL high.
— If either of the signals do not pulse to a TTL high, replace the A1 Keyboard.
(Refer to “A1 Keyboard” on page 2-8.)
— If the signals are pulsing to a TTL high:
a. Check the signal at J15-106 and J15-107 of the A23 Motherboard.
— If the signals are pulsing to a TTL high, replace the A12 CPU.
(Refer to “A12 CPU” on page 2-30.)
— If the voltage is not present on J32-12, refer to “Power Supplies” on page 1-23.
— If the green LED is not lit, refer to “Power Supplies” on page 1-23.
Figure 1-11 J30 and J32 of the A23 Motherboard