back to TroubleShooting

= 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