T M 5 - 6 1 1 5 - 5 4 5 - 12
T O - 3 5 C 2 - 3 - 4 4 4 - 1
N A V F A C P - 8 - 6 2 6 - 1 2
T M - 0 0 0 3 8 G - 1 2
3 - 1 4 6 . 1 E l e c t r i c G o v e r n o r C o n t r o l B o x F r e q u e n cy
A d j u s t R h e o s t a t ( M E P 1 1 5 A ) .
g. The frequency adjust rheostat ( 1 , F i g 3 - 2 4 . 2 )
will adjust the oscillator frequency of the control box (2).
The control box compares the oscillator frequency with the
signal frequency sent from the magnetic pick up speed
sensor (3). This sends the proper voltage to the electric
governor actuator (4) which controls the speed of the engine.
Normally this rheostat is only adjusted when the
control box is changed or when there is a
requirement to change the frequency of the
~. If the frequency of the generator fluctuates or is
incorrect and cannot be adjusted by the Frequency Adjust
( 2 9 , F i g 2 - 1 0 ) control located on the generator set control
panel, do not adjust the rheostat on the Electric Governor
Control Box until the following checks are made:
(1) Frequency Adjust ( 2 9 , F i g 2 - 1 0 ) on generator
set control panel is in mid-position.
(2) The magnetic pickup speed sensor is checked
by removing its connector plug and sensor ( 3 , F i g 3 - 2 4 . 2 ) .
Ensure there is no dirt or magnetic particles on the sensors
end. To install the sensor, turn slightly by hand until the tip
contacts the top of the Ring Gear Tooth (5). Then back out
three- quarters of a turn and secure with jam nut (6).
Reconnect wiring on the magnetic pickup speed sensor (3).
Ensure DC power source is disconnected before
the following step is accomplished. Serious
injury could result if this procedure is not
(3) Remove connector plug (P22) from J-22 (7)
and using a multimeter the following checks should be made:
on P22; pin G to ground should be O ohms; pin B to D
8 ohms; pins T to S should read between 50 to 500 ohms;
pins F to R 500 ohms; pins R to K 2,000 ohms and
pins J to H should read 85,000 ohms. Reconnect the
battery, DC Control Circuit Breaker ( 2 0 , F i g 2 - 1 0 ) pushed
in and the Start, Run, Stop Switch ( 3 2 , F i g 2 - 1 0 ) placed in
the Run position. Connect the Multimeter between pin C
and ground. A reading of 24 VDC should be obtained.
Disconnect DC power source and connect plug (P22) to
J22 (7, Fig 3-24.2);
governor actuator linkage.
The Frequency Adjust Rheostat (1, Fig 3-24.2) is
a multi turn rheostat and will not handle
damage to the rheostat will result. Adjust with
(5) If the generator frequency is either high of low
with the Frequency Adjust ( 2 9 , F i g 2 - 1 0 ) control located on
the generator set control panel in mid position, adjust the
Frequency Adjust rheostat ( 1 , F i g 3 - 2 4 . 2 ) in small
increments. Check the Frequency Meter (3, Fig 2-10) on the
generator control panel after each increment. Adjust until
the proper frequency is attained.
(6) If you cannot get the correct frequency after
completing all of the above checks, notify higher level of
maintenance for troubleshooting and repair.
C h a n g e 1 5
3 - 7 2 . 1