Hobart 90 C 20 Operation And Maintenance Manual page 92

OM-2031
(9) Measure governor actuator input signal. See Par. 3, E, (4), (a).
(10) Measure governor magnetic pickup signal. See Para. 3, E, (4), (b).
(11) Check speed limiting governor
Set engine speed-limiting governor to 2300 + 25 RPM. See John Deere Diesel Handbook in
Chapter 6 for instructions on how to set the governor.
(12) Check adjustable voltage range in automatic operating mode.
(a) Observe voltmeter a nd turn rheostat CLOCKWISE to full clockwise position. Maximum volt-
age should be at least 134 V AC, or higher.
NOTE: If voltage should decrease when the knob is turned clockwise, it indicates that internal wiring of
the voltage regulator is incorrect. Replace the complete regulator tray assembly.
(b) Observe voltmeter and turn rheostat knob to full COUNTERCLOCKWISE position. Minimum
voltage should be 108 V AC, or lower.
(13) Observe voltmeter and adjust rheostat to obtain 115-V AC voltmeter reading.
(14) Check adjustable voltage range in manual operating mode.
(a) Open the generator control tray (14, Fig. 1) and place the automatic-manual switch (33) in
MANUAL position.
(b) Observe voltmeter (2) and turn manual control rheostat (32) CLOCKWISE to full clockwise po-
sition. Maximum voltage should be at least 160 V AC.
(c) Observe voltmeter and turn rheostat (32) to full COUNTERCLOCKWISE position. Minimum
voltage should be 95 V AC or less.
(d) Adjust voltage to 115 V AC, then return the automatic-manual switch to AUTOMATIC position.
(15) Position load bank switches, etc., to apply a light load to the generator.
(16) Place the load contactor "on-off" switch (20, Fig. 1) in the top, spring loaded, CLOSE position.
Hold in this position momentarily. Hold in this position momentarily. The indicating light (22) should
glow GREEN and an amperage value should appear on the AC ammeter (4).
(17) Release the switch (2) and allow it to return to the center ON position. The load contactor should
open immediately, and the generator "on" indicating light should go OFF. This is because the plug in-
terlock relay (Ref. 1-1; 1, Fig. 8) is not receiving power from an outside source of 28 V DC. It indicates
that the plug interlock contacts are OPEN as they should be when the interlock coil is not receiving 28-
V DC power.
(18) Open the protective relay tray and place the test bank switch (34, Fig. 1) in TEST BANK position.
(19) Again place the load contactor switch (20) in the top, CLOSE position. Light (22) should glow
GREEN and remain ON when the switch is released and allowed to return to the center ON position.
This indicates that the test bank switch (34) is functioning to by-pass the plug interlock relay.
(20) Return the test bank switch to AIRCRAFT position. The load contactor should open at once and
the green indicating light (22) should go off.
(21) Connect a source of 24-V DC power (two twelve-volt batteries connected in series) to terminals
"N" and "F" (or "E") at the output terminal panel. Connection polarity should be: MINUS to terminal N
and PLUS to terminal E or F.
(22) With test-bank switch in AIRCRAFT position, hold the contactor operating switch (20) in top,
CLOSE position momentarily. The generator "on" indicating light (22) should glow GREEN and re-
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August 5/89 Revised