DOCNUMBER 9500
Document Issue 1, Revision 7
June 2009 Page 9–7
Alpha Radio Products Alpha 9500 HF Linear Amplifier Operating Manual
Product Release 1 Diagnosing Faults
The tune capacitor has an opto-interrupter that is actuated by a small vane
on the drive shaft. When the amplifier is turned to the ON2 or ON/AMP
position, the stepper controller attempts to move the vane until it just
occludes the opto-interrupter. This position is registered as a 0 (zero) for
the tune capacitor, and represents the minimum attainable capacitance for
that capacitor. Maximum capacitance is attained when the stepper motor
controlling the tune capacitor has taken 100 steps. The stepper motor
controller counts how many steps it takes, adding when the capacitance
increases and subtracting when the capacitor decreases. The count
(between 0 and 100) is the tune capacitor position. When the master
controller (MC) sends a command indicating that a new tune capacitor
position is desired, the stepper motor controller knows in which direction
and for how many steps to turn the capacitor.
Resolution 1. Unplug the amplifier, wait 30 seconds, and plug it back ON to the
ON2 or ON/AMP setting.
2. Even if the last fault is still fault 9, attempt to turn the tune capacitor
from the buttons on the front panel or from the AR9500 PC
application. If the capacitor responds, the fault may have cleared.
3. If the fault persists, contact ALPHA technical support. If possible,
send them the contents of the fault log. To display the fault log, from
the AR9500 PC application, open the Fault window and select Tools
> Get fault log.
Fault code 10
Description Load cap zero failure.
Explanation The stepper motor controller is unable to determine the zero position for
the load capacitor.
The load capacitor has an opto-interrrupter that is actuated by a small vane
on the drive shaft. When the amplifier is turned to the ON2 or ON/AMP
position, the stepper controller attempts to move the vane until it just
occludes the opto-interrupter. This position is registered as a 0 (zero) for
the load capacitor, and represents the minimum attainable capacitance for
that capacitor. Maximum capacitance is attained when the stepper motor
controlling the load capacitor has taken 100 steps. The stepper motor
controller counts how many steps it takes, adding when the capacitance
increases and subtracting when the capacitor decreases. The count
(between 0 and 100) is the load capacitor position. When the master
controller (MC) sends a command indicating that a new load capacitor
position is desired, the stepper motor controller knows in which direction
and for how many steps to turn the capacitor.
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