TM 5-6115-465-34
T035C2-3-446-2
NAVFAC P-8-625-34
TM 06858B/06859D-34
(1) If the FL - NL or NL - FL transient ex-
NOTE
ceeds 1-1/2 percent of rated speed and/or does not
If the drift in paragraph (4) is excessive,
re-establish stable engine operating conditions with-
realign the control unit following the
in one second, realign the control unit in accord-
procedure outlined in paragraph 4- 7j.
ance with paragraph 4-7j. Also follow this proced-
ure if the engine speed hunts. If the set cannot be
(5) At constant ambient temperature, constant
stabilized, check sockets A and B of plug P-21 (fig-
load, constant voltage and constant barometric pres-
ure 4-38) for 24 Vdc (A is positive).
sure, the set frequency should remain within a band-
(2) If the engine speed increase to above
width of 1 percent of rated frequency far a period of
4 hours. If this bandwidth has been exceeded, re-
nominal operating speed, check sockets A and B of
align the control unit in accordance with paragraph
P-17 (figure 4-38) for 120 Vat. If it is missing,
troubleshoot the generator set wiring. Refer to
schematic and troubleshooting diagram plates located
on inside of left and right engine compartment doors
(6) If the preceeding solutions to the specific
problem do not resolve the problems, replace and
repair the control unit, actuator (paragraph 3-42).
of the frequency adjusting circuit consisting of R4
(250 ohms) rheostat R1 frequency adjust (500 ohms)
or load measuring unit (paragraph 4-6) as required.
and R6 (250 ohms) fixed resistor. Measure the
total circuit resistance across N and T of harness
Removal.
c.
plug P17 (figure 4-38). The circuit resistance should
(1) Tag and disconnect electrical connectors
be 1000 ohms (5 percent tolerance). After testing for
to governor control unit.
correct total resistance, test the operation of the
frequent y adjust rheostat by connecting an ohmmeter
(2) Remove nuts (1, figure 4-15), lockwashers
across pins M and T and revolving the frequency ad-
(2), nuts (3), lockwashers (4) and bracket (5), threaded
just rheostat trough its entire travel. The resistance
should vary from 750 ohms to 250 ohms. Repeat this
rod (6) and lift governor control unit from mounting
bracket.
procedure using the ohmmeter across pins M and N
of the harness plug. If the problem persists, check
sockets A and B of plug P-21 (figure 4-38) for 24 Vdc
d.
Disassembly.
(A is positive).
(1) Disassemble governor control unit (7
(3) If the engine speed remains below the
through 58) only as is necessary for inspection, test-
ing, and replacement of parts.
nominal operating speed, adjust R 1. If there is no
improvement, check the resistance of the frequency
adjust circuit. Disconnect P-17 and check the resis-
NOTE
tance of the frequency adjust circuit consisting of
Disassembly and repair of the electric gov-
R4 (250 OhmS ) fixed resistor, R1 frequency adjust
rheostat (500 ohms ) and R5 (250 ohms, 5 percent)
ernor control unit at the field level is re-
fixed resistor. Measure the total circuit resistance
stricted to removal of the cover, connectors,
across N and T of harness plug P-17. The circuit
potentiometers and test jacks. Further dis-
resistance should be 1000 ohms (5 percent tolerance).
assembly requires unpotting which can be
After testing for correct total resistance, test the
performed by depot maintenance personnel
operation of the frequency adjust potentiometer by
only.
connecting an ohmmeter across pins M and T and re-
volving the travel. The resistance should vary from
(2) Remove screws (7) and lockwashers (8) and
750 ohms to 250 ohms. Repeat this procedure using
carefully lift cover and situate at angle to prevent
the ohmmeter across pins M and N of the harness
potting compound from contacting variable resistors
plug. Disconnect actuator electrical connector before
and connectors.
making this measurement. Push actuator piston all
the way down and adjust engine speed with manual
CAUTION
throttle. If this value resistance is measured, check
sockets A and B at plug P-21 for 24 Vdc (A is posi-
Flash point of potting compound is 515F
tive).
(268. 3 C). Do not allow oven to reach
this temperature. The melting tempera~
(4) If the set is operating at a constant load
ture of potting compound is 165F (73.8 C).
and voltage and during an eight-hour period the change
in ambient temperature does not exceed 60 F, the
set frequency should not drift beyond 1/2 of one per-
cent of rated frequency. The above requirement as-
(3) Place governor control unit in oven and
sumes that the set temperatures were stabilized
bake at +180F to 185F (+82.2 C to +85 C) for 11 to
at the initial and final ambient temperatures.
12 hours.
4-22
