Chevrolet 10 1971 Series Chassis Service Manual page 258

ENGINE-ELECTRICAL 6Y-8
Diodes are mounted in heat sinks to provide adequate
heat dissipation. The six diodes replace the separately
mounted rectifier as used in other types of application.
The diodes change the Delcotron A.C. current to D.C.
current.
The function of the regulator in the charging system is
to limit the generator voltage to a pre-set value by con­
trolling the generator field current.
The two unit double contact unit uses the field relay to
turn out the indicator lamp. The relay unit allows the
lamp to light (as a bulb check) with the ignition key on and
engine not running. When the engine is started and the
generator begins to charge, the indicator light goes out
indicating that the system is operating normally.
The double contact regulator assembly (fig. 2c) consists
of a double-contact voltage regulator unit and afield relay
At regular intervals, inspect the terminals for corro­
sion and loose connections, and the wiring for frayed
insulation. Check mounting bolts for tightness. Check
the drive belt for alignment, proper tension and wear.
Because of the higher inertia and load capacity of the
rotor used in A.C. generators, PROPER BELT TENSION
is more critical than on D.C. generators.
Since the Delcotron and its companion regulator are
designed for use on negative polarity systems only, the
following precautions must be observed.
observe these precautions may result in serious damage
to the charging system.
1. When installing a battery, always make absolutely
sure the ground polarity of the battery, generator and
regulator is the same.
2. When connecting a booster battery, make certain to
connect the correct battery terminals together.
3. When connecting a charger to the battery, connect
the correct charger leads to the battery terminals.
4. Never operate the generator on an uncontrolled open
circuit. Make absolutely certain all connections in
the circuit are secure.
FIELD RELAY
"F " TERMINAL
NO. 2 TERMINAL
NO. 3 TERMINAL
NO. 4 TERMINAL
M AINTENANCE A N D ADJUSTMENTS
Failure to
VOLTAGE
REGULATOR
Fig. 2c -D o u b le Contact Regulator
unit. This unit uses two sets of contact points on the volt­
age regulator unit to obtain desired field excitation under
variable conditions. A wiring diagram of the regulator
internal circuit is illustrated in Fig. 2c.
Wiring harnesses are protected by fusible links. A
fusible link is a length of special wire, normally four
gauges smaller than the circuit it is protecting, used in
circuits that are not normally fused such as the ignition
circuit. The same size wire with a hypalon insulation
must be used when replacing a fusible link.
The links are located in the engine compartment wiring
harnesses and each link will be identified with its gauge
size. On most models there is a 16 gauge, red wire
fusible link installed as an integral part of the positive
battery cable or located between the solenoid battery
terminal and the junction block.
5. Do not short across or ground any of the terminals
on the generator or regulator.
6. Do not attempt to polarize the generator.
7. Do not disconnect lead at generator without first
disconnecting battery ground cable.
Trouble in the A.C. charging system will usually be
indicated by one or more of the following conditions:
1. Faulty indicator lamp or ammeter operation.
2. An undercharged battery (usually evidenced by slow
cranking speeds).
3. An overcharged battery (usually evidenced by exces­
sive battery water usage).
4. Excessive generator noise or vibration.
Described below are a series of on-the-vehicle quick
checks which are designed to assist the service technician
in locating troubles within the various components of the
engine electrical system. Additional checks, adjustments
and overhaul procedures of these components are also
described in " The Overhaul Manual" and should be re­
ferred to as necessary.
DOUBLE CONTACT
10-30 CHEVROLET TRUCK SERVICE MANUAL