[amsat-bb] G-5500 Troubleshooting

John Meeks jmeek at gaslightmedia.com
Sat May 1 14:22:26 PDT 2010

I need some help diagnosing my non operative g-5500 azimuth rotator. 
After a few no copy passes, I noticed the azimuth meter was not moving. 
Disconnecting my G232 interface, manual operation with the 5500 az 
switches produced no movement of either the meter or the antenna array. 
Elevation works fine.

Swapping the cable connections on the back of the controller allowed the 
azimuth switches to operate the elevation rotator.  I think this tells 
me the controller box is probably ok.  The ele switches did not operate 
the az motor. So, either cable, connector or motor?  Returned connectors 
to their original positions.

Measuring impedance on the cables in the shack using pin 6 as the common 
gave me 4.6 ohms on both pins 4 and 5 on the elevation cable. The 
azimuth cable gave me 4.5 ohms from 6 to 5 and 6 to 4 was OPEN.  So... 
could be the azimuth cable or connector.  Braving high winds I climbed 
my tall roof mounted tripod and swapped cables from az to el and el to 
az. The az cable was now controlling the elevation motor no problem.  
Azimuth still non-operational.  So have I  eliminated all but the 
azimuth motor?  Are there any other possibilities  to consider before I 
dismantle the whole rooftop array?

One more thing... Given that the cable tested OK, what does the open 
reading from 6 to 4 suggest? My reading of the schematic diagram is 
sketchy at best.

Any and all help will be greatly appreciated.

John Meeks

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