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[TowerTalk] HDR-300 wiring question

To: TowerTalk <>
Subject: [TowerTalk] HDR-300 wiring question
Date: Sat, 26 Dec 2009 20:46:11 +0000 (UTC)
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Well, I replaced the T2X with an old HDR-300 (S/N 40) and it turns the 4 el 
Stepp I r fine.  But, the digital readout is hosed.  As currently wired, I get 
no numbers, only three dashes.  I climbed to the rotor, pulled the housing off 
and confirmed the wiring of the potentiometer.  The resistance measurements at 
full CCW, half way and full CW are: 

Pin 8-9: always 1000 Ohms regardless of position 

Pins 8-10: CCW: 520, half: 344, CW: 141  Total range is ~380 

Pins 9-10: CCW: 480, half: 656, CW: 861  Total range is ~380 

The totals always add to 1000 as expected and the range is about 380 Ohms, near 
the specified 400 Ohms for the expected travel and overage. 

What bugs me is that the manual says: 

8-10: 1000 

9-10: 150-550 

8-9:   450-850 

I have checked three different revisions of the manual: the oldest that I have, 
a newer 300 rev and the 300A rev.  The details are the same in terms of the 
definitions of what pin goes to what physical terminal on the pot and the Cinch 

I pulled the lid on the control box and checked the connector to PCB wiring and 
it is correct. 

Any suggestions or readings from your rotor would be welcomed. 

Like I said, the beam will turn and that is an improvement! 



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