Messages Indicating The Internal Status Of The Equipment; Messages Indicating Measurement Failure - Agilent Technologies E4991A Service Manual

Messages
DC bias overload

Messages indicating the internal status of the equipment

Messages that indicate the internal status of the equipment include equipment irregularities
as well as the results of processing (or current processing status). These messages do not
have numbers.

Messages indicating measurement failure

DC bias overload
During application of DC bias voltage, a sudden change in the connection condition of the
DUT has lowered the direct-current impedance, resulting in momentary over-current at the
DC bias source.
Do not remove the DUT during application of DC bias. If this error occurs frequently
during normal measurement, this may be due to instrument failure.
PLL Unlock
An error has been detected in the internal PLL (Phase Lock Loop) circuit of the E4991A.
The PLL is used to generate a stable frequency source. This can occur due to an error of the
external reference signal or when the power is turned ON in a low-temperature
environment.
If the external reference signal has not been inputted or shows no error, instrument tuning
or repair is necessary. If the message does not disappear in a few minutes after turning the
power ON, instrument tuning or repair is necessary.
Power on test failed
An error has been detected during the self-test after turning on the power.
RF overload
There has been a ranging failure in the internal circuit due to a sudden change in impedance
caused by removing the DUT or some other reason during measurement.
Do not remove the DUT during measurement. If this error occurs frequently during normal
measurement, there may be instrument failure.
356 Appendix E