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Re: [TowerTalk] Yaesu G1000SDX control box problem

Subject: Re: [TowerTalk] Yaesu G1000SDX control box problem
Date: Mon, 17 Mar 2008 10:19:32 EDT
List-post: <">>
Hi John,
With the rotor powered up and connected to the rotor, measure the voltage  at 
pins 1 & 3 on the Molex (or Jones) connector on the back of the control  box. 
It should be 6 volts. When you rotate, the voltage at pins 2 and 3  should 
If there is no 6 volts, first check the connector. The Molex pins on the  
cable half have a tendency to work their way out sometimes. Inside the control  
box there is a 7806 voltage source and a 15 ohm, 3 watt dropping resistor right 
 on the top of the control box when you remove the cover. Check those 
directly  with respect to chassis.
If there is 6 volts, but no varying voltage on pin 2, the problem is either  
the rotor cable, the Cannon plug at the rotor, or the position pot inside the  
If you do have a varying voltage on pin 2, open the control box and measure  
the voltage across the motor that drives the indicator. If it has voltage on 
it,  the brushes are probably bad. If it does not, check the D1 bridge diode 
across  the 13 volt, center tap portion of the secondary of the power 
transformer. It,  along with two voltage regulators (pass transistor Q5, zener 
diode D4 
for the  pos side and pass transistor Q6, zener diode D5 for the neg side), 
supply  the split voltages needed by the comparator Q7 which drive the  motor. 
Hope this helps.
-John, N9RF

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