6Service
176 Keysight 34970A/34972A Service Guide
Unit Reports Error 705
This error may be produced if you accidentally turn off power to the unit during a
calibration or while changing a non-volatile state of the instrument. Recalibration
or resetting the state should clear the error. If the error persists, a hardware failure
may have occurred.
Isolating to an Assembly
– Remove all plug-in modules to isolate between the instrument and the plug-in
modules.
– Listen for a beep when you press the On/Standby switch. The main controller
can operate the beeper even with a display failure.
– Listen for the fan when you press the On/Standby switch. Fan operation
indicates some operation of the main controller and power supplies.
– Try to operate the instrument from a remote interface. If remote operations are
normal, the display should be replaced or repaired.
– Isolate the internal DMM by removing it. The instrument should operate and
pass self-test without the internal DMM installed. Disassembly procedures
start on page 184.
Unit Fails Self-Test
– Verify that the correct power-line voltage setting is selected.
– Remove all plug-in modules and run self-test again. If the instrument does not
show a failure, replace or troubleshoot the plug-in module.
– To isolate the internal DMM, disassemble the instrument and remove the
internal DMM. Disassembly procedures start on page 184. Run self-test again.
If the self-test passes, troubleshoot or replace the Internal DMM. If the
self-test fails, troubleshoot or replace the 34970A/34972A.
Power Supplies
Verify the power supplies generated on the 34970-66501 circuit board.
The front panel filament voltage, + 5 V backplane and +5 V fan are switched by the
On/Standby switch. All other power supplies operate whenever the AC power
cord is connected.
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