Service manual

RC2000 Service Manual Chapter 4 Common RC2000 Questions 25
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4.1.6 No Polarization Control Device Attached to the RC2000
If there is no polarization control device used with the RC2000 the controller should be configured for
polarotor operation. This is done by setting the Rotating Feed Present CONFIG mode item to 0 (No).
When storing a satellite in memory (via SETUP mode) make sure that the current polarization position
(displayed to the right of the POL: or PL: banners) is not at the CW or CCW limit. Use the polarization
jog keys (labeled POL CW or POL CCW) to ‘jog’ the polarization out of the limit condition.
4.2 Antenna Azimuth and Elevation Errors
An antenna azimuth or elevation error is indicated on the controller by a flashing ANT AZIM or ANT ELEV
message on the bottom row of the display. The cause of the error is displayed via RESET mode. These
errors are triggered by one of three possible events:
1. The antenna was commanded to move and an overcurrent conditions occurred. In this case the
RESET mode azimuth or elevation error status will display as DRIVE. The RC2000 uses a solid state
drive. The current threshold is 8 amps. There are current limit threshold adjustments on the
controller's drive board (the one with the heat sink).
2. The antenna was commanded to move and no movement was sensed. In this case the RESET mode
elevation error status will display as JAMMED. This could be caused by the antenna actually being
jammed or the sensor could have failed (the antenna was really moving but the movement was not
sensed). If the position sensor failed the controller's position count would be in error.
Note that there is also a thermal circuit breaker present on the controller which protects the drive
circuits. A tripped circuit breaker can trigger the JAMMED alarm. The circuit breaker is accessible via
the back panel. The circuit breaker has tripped and needs to reset if the button on the circuit breaker
is protruding from the mounting bezel. Reset the breaker by depressing the button. It may be
necessary to wait several minutes before the button will stay in.
3. The antenna was not commanded to move and movement was sensed (i.e. a position pulse was
received). When this error occurs the RESET mode elevation error status will display as RUNAWAY.
This error can be caused by:
i) Noise Pickup on the Sensor Lines. Please see the section on Position Count Errors.
ii) The Az/El Fast Deadband or Az/El Slow Deadband CONFIG mode items need to be increased.
When the antenna has been moving and is suddenly commanded to stop, the antenna must coast to a
stop within 'Fast Deadband milliseconds if the antenna was moving fast or within 'Slow Deadband
milliseconds if the antenna was moving slow. If the antenna moves at a single speed the 'Fast and
'Slow Deadband values MUST be set to the same value.
If a position pulse is received by the controller and the controller is not either moving or in a coast
period defined by the Az/El Fast/Slow Deadbands described above a RUNAWAY error will occur.
If the RUNAWAY error occurs immediately after an antenna move it is probably due to insufficient
'Fast or 'Slow Deadband intervals.
For RC2000C model antenna controllers the RUNAWAY error can be disabled. See section 7.3 of the
controller manual. Note that it is generally not advisable to disable RUNAWAY error sensing.
iii) The position sensors are placed on the fundamental axis of the controller. The controller is
designed to be used with antenna's powered by linear actuators which have the position sensors
located on the 'motor' side of the gear reducer. With the position sensors placed on the 'motor' side of
the gear reducer, wind loading will not generate stray position sense pulses.
If the position sensors are located on the fundamental axis of the antenna, movement due to wind will
cause position counts to be produced. The pulse sense circuits of the RC2000 are normally always