20 Amp Regulated Alternator; Alternator Output Test; Testing Dc Output Charging Wire; Testing Ac Output - Generac Power Systems GTH760 Service Manual

20 AMP reGulATed AlTerNATor

The 20 amp regulated alternator system provides AC current
through two output leads to the regulator-rectifier. The regula-
tor-rectifier converts the AC current to DC, and regulates the
current to the battery. The charging rate will vary with engine
RPM and temperature.
The stator, regulator-rectifier and flywheel are NOT inter-
changeable with any other alternator system.
WHEN CHECKING THE ALTERNATOR COMPONENTS,
MAKE THE TESTS IN THE FOLLOWING SEQUENCE:

ALTERNATOR OUTPUT TEST:

Temporarily, disconnect stator wire har ness from
regulator-rectifier.
1. Insert RED test lead into
2. Insert BLACK test lead into
3. Rotate selector to (AC volts) position.
*
CAuTIoN: ATTACH MeTer TeST leAdS To AC
ouTPuT TerMINAlS (wHITe wIreS) beFore STArT-
ING eNGINe. IF STATor IS GrouNded (deFeCTIve),
ANd MeTer TeST leAdS CoNTACT CeNTer dC
ouTPuT PIN, ArCING MAY oCCur wHICH MAY
dAMAGe wIrING.
Figure 7-1. Testing AC Output
4. Attach RED and BLACK test lead probes to AC output
terminals (white wires), as shown in Figure. 7-1.
(Meter test clip leads may be attached to either AC
output terminal.)
5. With the engine running at 3600 RPM, output should be
6. If no or low output is found, check for bare wires or any

TESTING DC OUTPUT CHARGING WIRE:

charging wire circuit. If a problem exists in the wiring it can
be corrected before testing regulator-rectifier.
reg u la to r- re c ti fi er.
receptacle in meter.
1. Insert RED test lead into
receptacle in meter.
2. Insert BLACK test lead into
3. Rotate selector to
4. Attach RED test lead probe to DC output wire terminal
5. Attach BLACK test lead probe to negative battery
6. Turn equipment keyswitch to ON position. Meter should
7. If meter does not display battery voltage, check for blown
TESTING REGULATOR-RECTIFIER:
1. Using a digital multimeter, test the battery voltage while
7-1
no less than:
26 volts - 20 Amp System
other obvious defects. If "shorted" leads are not visible,
replace the stator.
A simple test may be performed to test the DC output
L e a v e s t a t o r w i r e h a r n e s s d i s c o n n e c t e d f r o m
Equipment keyswitch must be in OFF position.
(DC volts) position.
(Red Wire), Figure 7-2.
terminal.
display battery voltage.
fuse or broken or shorted wires.
Figure 7-2. Testing DC Output Wire
the engine is NOT running.

SeCTIoN 7: AlTerNATorS

receptacle in meter.
receptacle in meter.
7