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Trouble Shooting - Bias

bias disconnection

Symptom

• biasctrl is in state DISCONNECTED

Solution

• Do _RECONNECT_
• Send a command like _REQUEST_STATUS_
• Sometime the bias crate will disconnect again, do _RECONNECT_

Not Helping

• do not close or kill biasctrl

OverCurrent Status

Symptom

• when biasctrl ramped the voltage, it get in the state OverCurrent

Solution

1. BIAS_CONTROL/RESET_OVER_CURRENT_STATUS
2. then ramp down voltage, e.g. BIAS_CONTROL/SET_ZERO_VOLTAGE
3. maybe you have to repeat 1. and 2. as during ramping down another OverCurrent can happen

Not Helping

• do not close or kill biasctrl

Repeated OverCurrent Status

if OverCurrent appears again

• switch to bias-off measurement (see https://trac.fact-project.org/wiki/SpecialMeasurements)
• try data taking again after ~ 1 hour

if this continues for several hours, you may go to bed earlier

Status NotReferenced

Symptom

• biasctrl is in state NotReferenced

Solution

• start the Ramping again
  • biasctrl/START

Not Helping

• do not close or kill biasctrl

Locked

Security Limit

biasctrl goes into Locked state (after ramping down the voltage) in case

• the (uncalibrated) currents increase to values > 2200 DAC
• the voltage is on after the end of nautical twilight

Solution

• investigate why biasctrl went into Locked
• report in the logbook what happened
• in case you consider it safe, you may send UNLOCK

Not Helping

• do not close or kill biasctrl