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Section V – Maintenance and Servicing
Symptom:
No AVM-2000 Meter readings and no signal at the ISOLATED OUTPUT on all ranges.
Action: Ensure the AVM-2000 front panel OPERATE/ZERO Switch is in the OPERATE position.
If not above, check that the power supply voltage being delivered to the Isolated Analog Subsystem as
measured between pins 1,2 and ,4 at connector J1 is + 5 VDC ± 0.25 volts.
If + 5 volts is not being delivered to the Isolated Analog Subsystem, check the voltage into the Front
Panel Subsystem at connector J1 (pin 3 to 9 and pin 4 to 10). This should be b5.3 and 7.0 volts.
If no voltage is present, there is a Power Supply Subsystem / Battery problem.
Action: Use the steps above to isolate a Power Supply Subsystem / Battery problem.
If the voltage is present at the input to the Front Panel Subsystem but not being delivered to the Isolated
Analog Subsystem, the Front Panel Subsystem is defective.
Action: Replace the Front Panel Subsystem
.
If not above, rotate the AVM-2000 RANGE control to the 100 mV range, and apply a 100 mV DC input
signal to the AVM-2000. Using an oscilloscope (or pulse detecting logic probe), check for serial
communications from the Isolated Analog Subsystem to the Front Panel Subsystem--19,200 baud 10
character bursts should be present at connector J2 Pin 6.
If bursts are present, the Front Panel Subsystem is not properly detecting and interpreting them.
Action: Replace the Front Panel Subsystem. If no bursts are present, look for similar bursts from the Front
Panel Subsystem to the Isolated Analog Subsystem at connecter J2, Pin 5 of the Front Panel Subsystem.
If no bursts are present, the Front Panel Subsystem is not properly generating them.
Action: Replace the Front Panel Subsystem.
If bursts are present, the Isolated Analog Subsystem is not properly detecting and interpreting them.
Action: Replace the Isolated Analog Subsystem.
Symptom: AVM-2000 does not operate properly in some RANGE control positions but operates correctly
on other ranges or the OFFSET function, FILTER function, Z IN function or ZERO function fails to operate,
a defective Isolated Analog Subsystem is indicated.
Action: Replace the Isolated Analog Subsystem.
