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

Robert Bruninga bruninga at usna.edu
Fri Nov 18 22:21:11 UTC 2016

> When you say the voltage pots do not change anything,
> I suppose you mean adjusting them does not fix the problem.

No, I mean they do not affect either AZ or EL meter reading.  Turn pot
end-to-end and meters still correctly read the AZ and EL and an external
voltmeter does not show any change on the   We used the full scale pots to
calibrate the system, since the volts adjust pots do nothing..

Further, when the 10% glitch happens, it stays down permanently even with
the motors not turning and no fingers on the switches... until it glitches
back up eventually..


-----Original Message-----
From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of KO6TZ Bob
Sent: Friday, November 18, 2016 5:01 PM
To: amsat-bb at amsat.org
Subject: Re: [amsat-bb] G5500 AZ/EL controller Glitching?


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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