[amsat-bb] G5500 AZ/EL controller Glitching?

KO6TZ Bob my.callsign at verizon.net
Fri Nov 18 22:00:35 UTC 2016


My guess is that since it is only when turning Left, the problem is with 
the "bow-tie" or something mechanical in the break that is causing a lot 
of drag on the motor when turning left.  Try measuring the voltage 
between lug 6 & 4 turning left and compare to the voltage between 6 and 
5 turning right.  I suspect the load or drag is drawing down the 
secondary side of the AC transformer, affecting both the feed back 
circuits and the drive motor.

Easier said than done, since as you state the issue is intermittent and 
the switching action clears the problem.

When you say the voltage pots do not change anything, I suppose you mean 
adjusting them does not fix the problem.  That is, it is not a dirty pot 


Apparently the internal 6v supply is dropping since both meters glitch down
and an externmal voltmeter on the rotator feedback terminals also show the
same10% drop in the 6v line. (though it appears to be a constant 5.5 volts
not 6)  And then glitches down from the 5.5.

Also noticed the Adjust voltage pots on the back do not change anything.

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