The following procedures are designed to support prime focus observing or testing that requires turning off power to feed arm servo systems (SCU).
Info
If this type of observing is to be done for an extended period (many hours), SCU power should be turned off in the receiver room (D15 Service box, main breaker) instead of on the allidade at the D14 breaker.
| STEP | ACTION |
|---|
| 1 | Stow Sub Reflector unless already stowed. |
| 2 | Set up Antenna Control screens for Prime Focus observing: Optics Mode = Prime Focus Optics; Subreflector Mode = Prime; Pointing Coefficients = Prime Focus with focus tracking OFF; Pointing Models = Focus Tracking OFF. |
| 3 | Using M&C or the OCU/OCT, set the prime focus axis as follows: Prime Focus Y axis = 1030mm (40.55 in.); Prime Focus X axis = 560mm (22.05in.) |
| 4 | Extend Prime Focus boom (can be done later if necessary, but must be done prior to shutting power off). |
| 5 | With M&C in control of the antenna, go to the Antenna Control Drives tab and set the SCU Control State to disabled. |
| 6 | Proceed to Powering Off SCU Servos when ready. |
Powering Off SCU Servos
| STEP | ACTION |
|---|
| 1 | Confirm the prime focus axis are set. |
| 2 | Turn OFF the D14 breaker in the D1A service box, Allidade power cabinets. |
| 3 | The antenna is now set for prime focus observing with SCU power off. |
Two problems can occur inhibiting antenna operation with SCU power off:
- Problem #1 Antenna Disabling Status/Fault (e.g., feed arm E-stop, SCU not enabling properly message that won't clear). These problems are likely caused by not setting the M&C antenna SCU control state to disabled prior to shutting off power.
- Problem #2 Illegal Command or Value. This problem can occur if the Antenna Control Update button is used while the SCU control state is disabled (may load zeros in prime focus X, Y, and Focus fields).
| PROBLEM | SOLUTION |
|---|
| Problem 1 | Turn ON D14 breaker. Clear the M&C faults. With M&C in control of the antenna, go to the Antenna Control Drive tab and set the SCU Control State to disabled. Turn OFF D14 breaker. |
| Problem 2 | On the Antenna Control Screen, Prime Focus Ctrl tab, replace any zeroed values with legal ones. Any legal values will work and will not affect observing. Upon pressing Move to, the faults should clear. |
Restoring SCU Power for Normal Operations
| STEP | ACTION |
|---|
| 1 | Turn ON D14 breaker in the D1A service box, Allidade power cabinets. |
| 2 | Setup M&C antenna control screens for normal (feed arm power on) observing as necessary. |
-- DavidRose - 6 Feb 2008
Revision r1.5 - 06 Feb 2008 - 16:49 GMT - DavidRose
Parents: WebHome > TelescopeOperations
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