Anritsu 682XXB - Manual (Page 179)

682XXB/683XXB MM 5-13
TROUBLESHOOTING
TROUBLESHOOTING TABLES
G If the voltage is correct, the Front Panel assembly or the
cable between Motherboard connector A20J22 and the
Front Panel assembly may be defective.
G If the voltage is incorrect, the +24V standby power supply
may be loaded down by (1) a shorted oven heater for the
100 MHz reference oscillator located on the A3 PCB, (2) a
shorted heater for the optional 10 MHz high stability time
base (if installed), or (3) a defective Front Panel assembly.
Signal Generator Will Not Turn On
( OPERATE light is ON )
Normal Operation: When the 682XXB/683XXB is connected to the
power source, the
OPERATE light should illuminate and the instru-
ment should power up.
Step 1. Remove the 682XXB/683XXB top cover and the cover over
the A18 and A19 PCBs.
Step 2. Connect the negative lead of the DMM to A18TP1 and the
positive lead to A18TP3.
Step 3. Check for a +23.3 ±0.5 volt reading on the DMM.
G If the voltage is correct, go to step 4.
G If the voltage is incorrect or missing, the Front Panel
assembly or the cable between Motherboard connector
A20J22 and the Front Panel assembly may be defective.
Step 4. Press the front panel RF OUTPUT ON/OFF button. Do the
yellow and red LEDs toggle?
G If yes, the malfunction may be caused by a failed front
panel circuit. Replace the Front Panel assembly.
G If the LEDs do not toggle or if both LEDs are lit, the prob-
lem may be caused by a malfunction on the A17 CPU
PCB.
Table 5-4. Malfunctions Not Displaying an Error Message (2 of 6)