DRESSTA TD-25M EXTRA, Service Manual

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ELECTRICAL
SECTION 8
Page 27
DRESSTA TD-25M EXTRA
ALTERNATOR
8. TROUBLESHOOTING PROCEDURES
a. Energizing Speed
The energizing speed is the rpm at which the regulator turns on to energize the field coil. This
speed is higher than some speeds at which output can be obtained. Therefore, when checking
output at low speeds, increase the speed until the regulator turns on, then reduce the speed
to check the output. No output can be obtained until the regulator turns on. Once the regulator
turns on, it will remain turned on until the engine is stopped.
b. Rated Voltage
The Integral Charging System output preferably should be checked at the RATED VOLTAGE given
below. However, it is permissible to check the output in amperes at any voltage within the
OPERATING RANGE listed below, since the current output will be quite close to the value that
would be obtained at RATED VOLTAGE. The voltage should never be allowed to rise above the
OPERATING RANGE for any length of time.
SYSTEM
VOLTAGE
RATED
VOLTAGE
OPERATING
RANGE
24 28.0 26.0 - 30.0
It should be noted that the voltage may be below the OPERATING RANGE if the battery is in
a low state of charge. However, as the battery receives a charge, the voltage will rise to some
value within the OPERATING RANGE.
c. Magnetizing the Rotor
The rotor normally retains magnetism to provide voltage buildup when the engine is started. After
disassembly or servicing, however, it may be necessary to reestablish the magnetism. To
magnetize the rotor, connect the Integral Charging System to the battery in a normal manner, then
momentarily connect a jumper lead from the
battery positive post to the Integral Charging
System relay terminal,
identified in Fig. 8.3. This procedure will restore the normal residual
magnetism in the rotor.
A basic wiring diagram is shown in Fig. 8.6. On 24-Volt systems, two 12-Volt batteries will
be connected in series.
1. Insure that an undercharged condition has not been caused by accessories having been left
on for extended periods.
2. Check the drive belt for proper tension.
3. If a battery defect is suspected, check per the applicable Battery Test.
4. Inspect the wiring for defects. Check all connections for tightness and cleanliness, including the
cable clamps and battery posts.
5. Connect a voltmeter from POS. terminal on Integral Charging System to ground. A zero reading
indicates an open between voltmeter connection and battery.
6. With all accessories turned off, increase engine speed as required to obtain maximum voltage
reading.
7. If voltage exceeds 30 Volts on a 24-Volt system remove Integral Charging System for repair
as covered below under heading of INTEGRAL CHARGING SYSTEM REPAIR.