IMPROPER METER INDICATION
CHECKING THE CONTROL UNIT
The brake and motor operate independently of the
indicating system. If the pilot light bums at proper
brilliancy, the instrument transformer is okay and the
output is not shorted. Check the 1/8 amp meter circuit
fuse with an ohmmeter. Check for about 13 VDC
across Terminal No. 3 and No. 7 with the switch
'operated. If the proper voltage is not obtained, check
the individual components in the meter circuit. If the
13 VDC is present, check for 500 ohms across rotator
leads No. 3 and No. 7. If 500 ohms is present from
No. 3 and No. 7, see if the readings from No.3 to
ground and No. 7 to ground total 500 ohms.
NOTE: An intermittent condition in any component
in the rectifier or meter circuits within the control
box, as well as in the cable or potentiometer circuit
in the rotator itself can cause meter fluctuation or
error. Possible cause of such trouble may be
localized by placing a test DC meter across Terminal
No. 1 and No. 3 or No. 1 and No. 7 comparing the
action of the test meter with the panel meter.
NO ROTATION - INDICATION OK
Either the thermal cut-out in the power transformer
has opened or there is actually trouble in the motor
circuit. After allowing time for the thermal cut-out to
restore service, proceed to "Checking the Control
Unit" and "Checking the Rotator from Ground".
GROUND WIRES
Grounds on cable leads can bum out either the line
fuse or the small fuse in the meter circuit. If lead No.
3 or lead No. 7 is grounded, it shorts out part of the
potentiometer so that as rotation progresses to the
other end, the full DC voltage is applied across a
decreasing portion until current becomes so high that
the potentiometer burns out. Note also that any
grounds may put an overload on the power
transformer which could cause the line fuse to blow
or overload the rectifier circuit
so
that the 1/8 amp
fuse blows. For full explanations, refer to Figure 8
HELPFUL SUGGESTIONS
Be sure to check your rotator cable for shorting,
open circuits, incorrect wiring, intermittent
connections, shorted terminals, poor lead dress at
terminals, rodent damage, and mast support or thrust
b
i
bi di
1.
Voltages with Unit Plugged In.
To check the control unit, plug the line cord into
AC power. With no connections to the connector,
turn the on-off switch to the "ON' position, the
meter light will illuminate. The meter needle will
remain on the left hand "S".
Connector pins 1 and 2 should show 30 volts AC
(approximately) when the brake lever is
depressed.
Connector pins 1 and 5 should show 30 volts AC
with brake release lever depressed and CW lever
depressed.
Connector pins 1 and 6 should show 30 volts AC
with brake release lever depressed and CCW
lever depressed.
Connector pins 3 and 7 should show
approximately 13 VDC.
2. Resistances with Unit Not Plugged In.
Disconnect the AC power source and remove
the control cable.
The control box can be checked without
removing the cover by using a volt-ohmmeter to
check values across connector pins. Resistances
across Connector pins 1 thru 5 with clockwise
switch lever (right hand) depressed and across
Connector pins 1 thru 6 with counterclockwise
switch lever (left hand) depressed. Resistance
across input line cord with on-off switch in the
"ON'
position and the brake lever depressed
CHECKING THE ROTATOR FROM THE
GROUND
You may possibly avoid bringing the rotator down
by making electrical checks from the control box
position. This is done by disconnecting the cable
connector from the control unit. From the schematic
diagram, it is apparent that the resistance of the lead
wires will be added to the resistance of the motor
windings and potentiometer strip in making the
resistance checks as shown in Table 2.
