Titanium Satellite Servo drift SOLVED! (1 Viewer)

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KF4YLM

Active SatelliteGuys Member
Sep 20, 2017
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27
VA
For a whole month was plagued with seemingly random signal outages on my BUD. Swapped RX, LNB, DiSEqC switches, even the positioner (ASC-1). It started with a drop in SNR after about one hour on the same xponder. Eventually, I couldn't maintain lock for more than ten minutes.

The quick fix was to bump the positioner east or west. Noticed later that simply commanding a change in polarity would also fix it.

Hung a second servo on the back of the positioner in parallel and observed.... Placed a Sharpie mark at V. When the RX lost lock, I noticed the servo had moved off the mark.... Sometimes more than 100 deg!

Positioners like the ASC -1 send the pulse command to the servo for a few seconds, then the pulse line goes quiet. I watched this line with my o-scope. Periodic peaks of noise were visible, but way down from 5v. Occasionally, the servo's controller would interpret this noise as a PWM command and cause the motor to drift into a random position.

Tried some reactive filtering on the pulse line for a while without success.

Noticed that the second servo calmed the drift down to where it was happening every 27 minutes. Only device in the chain that might have some sort of periodic housekeeping was my Eaton UPS.

ASC-1 was on the battery side. Moved it to the surge only side. PROBLEM CURED!


Why did it get more frequent over the last month? Suspect this noise has something to do with the battery charge or battery capacity evaluation... As the battery aged, apparently the UPS was performing this noise-generating routine more often.
 
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KE4EST

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Suspect this noise has something to do with the battery charge or battery capacity evaluation... As the battery aged, apparently the UPS was performing this noise-generating routine more often.
This.
 
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