Generac Power Systems IM Series - Manual (Page 23)

2. Connect the positive (+) test iead of the a d-c voitnieter
to Pin 2 of Choke Moduie CM. Connect negative (-) test
iead to a ciean frame ground.
3. Crank the engine. The voitmeter should indicate about
7-10 volts d-c with engine cranking.
Test Results:
A. Engine won’t crank: Go to Problem No. 1.
B. Engine cranks but no d-c voltage is indicated: Replace
Choke Module CM and recheck for proper voltage. If
voltage is good, STOP test.
C. Engine cranks and normal voltage is indicated: Con­
tinue test.
4. Gain access to Brushes and Slip Rings (Fig. 16).
5. Connect the positive lead of a d-c voltmeter to the
terminal of the positive (+) brush (RED lead connection).
Connect voltmeter test lead to a clean frame ground.
6. Crank engine. The voltmeter should indicate about
7-10 volts d-c with engine cranking.
Test Results:
A. Engine won’t crank: Go to Problem No. 1
B. Engine cranks and no d-c voltage indicated, but volt­
age was indicated in Item 3 of test: Repair or replace
Wire 4 between Choke Module CM and the positive (+)
brush.
C. Engine cranks and normal voltage indicated: Go to
Step 7.
Step 7 - Check Stator Excitation Windings
Test Procedure: Disconnect Stator Excitation Winding
output leads 2 and 6 (Fig. 17) from the Electronic Voltage
Regulator. Set a VOM to its "Rxl" scale and zero the
meter. Connect VOM test leads across terminal ends of
Wires 2 and 6. The VOM needle should swing upscale
and Indicate the following resistance:
NP45G Units = 2.2 Ohms
NP55G Units = 1.8 ohms
NP65G Units = 1.6 ohms
*AII resistance values are plus or minus 10%.
Now, set the VOM to its "Rxl 0,000" scale and again zero
the meter. Connect one VOM test lead to Wire 2, and the
remaining test lead to a dean frame ground. You should
not detect any upscale movement (infinity) of the VOM
needle.
Test Results:
A. Excitation windings check GOOD: Go to Step 8. .
B. Excitation windings check BAD: Replace Stator As­
sembly.
NOTE: Also see INSULATION RESISTANCE TESTS
on Page 9. Typically, In the above test, a low resis­
tance indicates a shorted condition; a high resls-
tance Indicates an open condition._________________
Test 8 ■ Check Stator a-c Power Warnings
Test Procedure:, Test the Stator (Fig. 18) a-c power
windings as follows:
1. Disconnect a-c power winding output leads 11 and 22
from the Electronic Voltage Regulator.
2. Disconnect a-c power winding output lead 33 from
Circuit Breaker CB1.
3. At the wire nut junction of a-c output leads 22 and 44,
separate the two wires.
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