Mde Status Leds; Check/Test - Pol Motor; Theory Of Operation - Sea Tel 4012 GX KU-BAND Technical Manual

4012 GX Dealer Technical Manual
20.11.3.
20.12.

Check/Test - Pol Motor

20.12.1.
To ensure the LNB is correctly aligned to the linear polarized receive signal the antennas feed assembly can
be driven through a 270 degree range of motion by a 24VDC motor. Based on the vessels GPS position and
the look angle to the desired satellite the system will calculate the numerical value for the position of the pol
assembly. The ICU will then send the voltage to drive the pol motor until the pol pot/encoder outputs the
correct value, at which point the feed will be aligned to the incoming satellite signal (provided the
pot/encoder has been calibrated correctly). As the vessel sails and the GPS position changes the polarization
will be incrementally adjusted to maintain good cross pol isolation (alignment to the satellites linear signal).
One indication that there is a fault with the feed alignment of the system is that the target light will be
permanently illuminated on the MXP. The procedure for targeting is for the ICU/GICU to:
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If the system is unable to drive the pol motor or the pol pot/encoder has failed, the correct feedback signal is
not obtained, the system can't complete the targeting process and the antenna will stay in this position.
There are a variety of discrete pol errors which depend on the design of the feed assembly. These are related
to pol home flag, motor drive and pot or encoder feedback, Ascertain the exact error(s) and troubleshoot
accordingly.
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MDE Status LEDs:

20.11.3.1. MDE Motor Status (top 3 LEDs are CL, EL and AZ).
Green Motor is good.
Solid Red Motor or harness short circuit (winding-winding, winding-ground, or
winding to supply). Replace the appropriate motor. If that does not clear
the LED status, replace the MDE.
Solid Orange Hall sensor error (hall sensor or harness wire). Replace the motor. If that
does not clear the LED status, replace the MDE.
20.11.3.2. MDE Status LED (4
Green Motor Driver is good.
Solid Red Motor Driver fault detection. Operational software will never leave the
status LED solid red. Replace MDE.
Solid Orange Software update to the MDE in process.
Blinking Red Communication error with PCU. Check to assure that the harness
connections are seated properly. Check harness (pin-pin, wire-wire and
wire-ground) for good continuity. Replace MDE. Replace the main PCB.

Theory of Operation:

Calculate the azimuth, elevation and polarization pointing angles of the satellite
Drive elevation initially to 8 degrees above the actual elevation to the satellite (or below if the
elevation angle is above 83 degrees).
Drive azimuth to the actual azimuth pointing angle to the satellite.
Drive polarization to the actual polarity angle of the satellite. Polarity must be driven slowly and is
almost always last to reach its target
Sample OFF satellite AGC.
Drive elevation to the actual elevation pointing angle of the satellite.
Sample ON satellite AGC.
Calculate and set Auto-Threshold.
Diagnostics, Fault Isolation & Troubleshooting
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LED).
Document. No. 136879 Revision B
20-22