1. Change History Log

2. Contents

Change History Log        1

Contents        1

Applicable documents        2

Acronyms        2

Introduction        2

Filter exchange position definition        3

Reboot & Powercut        4

FCS crash/re-start        4

PC104 reboot/power-cut        4

One (or more) power supply shutdown        4

Mechanical issues        4

Linear rails: slave/master misalignment        4

Carousel clamps not locking        4

Carousel clamp fails to unlock        4

Carousel does not recognize socket position        4

Sensor issues        4

Carousel position sensor error        4

Carousel filter pin position sensors        4

3.   Applicable documents

4. Acronyms

5. Introduction

The filter exchange system may fail during operation or be in a non standard mode (after a power cut). This document will review the know “abnormal” condition and propose a set of action to bring the system back to a normal condition.    

6. Filter exchange position definition

7. Reboot & Powercut

1. FCS crash/re-start

2. PC104 reboot/power-cut

3. One (or more) power supply shutdown

8. Mechanical issues

1. Linear rails: slave/master misalignment

2. Carousel clamps not locking

Symptoms: a filter is engaged in the Carousel socket, with the presence sensors in the "lockable" range, and the Carousel clamps are not powered on, but the filter is not locked in the socket (at least one filter lock sensor value is too low).

Recovery: at this stage the Autochanger should still be at the Standby position, and still holding the filter (latches closed). If that is not the case, this should be done first, because the next step is to power on the unclamping motor for the clamp that is not fully closed. Then we can try to force the locking of the clamp by applying a positive current of +100 mA, the opposite of the negative current that is usually used to open the Carousel clamp. The power should then be cut off again from the unclamping motor.

Note: this incident can be a symptom of a larger mechanical issue, so it should be logged (telescope orientation, socket at standby, which clamp, sensor value).

3. Carousel clamp fails to unlock

Symptoms: a filter is held at Standby by the Autochanger, but when trying to unlock the Carousel clamps, one or both clamp lock sensors do not reach the "unlocked" state. These sensor thresholds are tuned, so reaching a value slightly above the unlock value is not an acceptable substitute.

Recovery: check that the Autochanger is indeed at the Standby position, and not for instance at the "ApproachStandby" position. When that is the case, we can define a slightly higher current (in absolute value) to unclamp in the CCS parameter interface, or do the unclamping procedure manually...

Note: this incident can be a symptom of a larger mechanical issue, so it should be logged (telescope orientation, socket at standby, which clamp was affected, what current was required to unclamp).

4. Carousel does not recognize socket position

9. Sensor issues

1. Carousel position sensor error

2. Carousel filter pin position sensors

3. Autochanger online clamps sensor errors

4. Autochanger latches sensor errors