Chevrolet 70 1969 Series, Shop Manual

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ENGINE ELECTRICAL 6Y-30
FULL TRANSISTOR TYPE REGULATOR
(MODEL 1116374 OR 1116378)
GENERAL
The full transistor regulator (fig. 17) is used
on models equipped with the 62-amp generator as
shown in "Model Application Chart” previously.
The regulator is composed of transistors,
diodes, capacitors and resistors which form a
completely static electrical unit containing no
moving parts.
The function of the regulator is to limit volt­
age to a given value. The voltage at which the gen­
erator is limited is determined by the regulator
adjustment which, when adjusted, remains prac­
tically unchanged. Refer to "Regulator Adjustment”
later in this section.
C A U T IO N
The field wire term inal must not be
grounded or flashed when regulator is
connected into circu it as instant damage
to tra n sisto rs will result.
OPERATING PRINCIPLES
In the circuit illustrated in Figure 2 in "G en ­
erating System General Description" section, when
ignition switch is closed and engine is not running,
the ammeter will show a discharged condition or
the indicator lamp will "light," to indicate the gen­
erator is not charging. The current flow can be
Figure 17— Full Transistor Type Regulator
(Model 1116374 or 1116378) (Typical)
traced from the battery to the " B A T " terminal on
the ignition switch, through the indicator lamp and
resistor, then to No. 2 or 4 terminal on the regu­
lator. From here it continues to flow through tran­
sistor TR-1 to " F " terminal on the regulator and
on through the generator field winding to ground,
completing the circuit back to the battery.
When the engine is started and generator be­
gins to operate, A .C . voltages are induced in the
generator stator windings. These voltages are
changed or rectified to D .C . voltage which appears
at the output, or " B A T " terminal on the generator.
The generator then supplies current to charge the
battery and operate vehicle accessories.
On 62-amp systems voltage from the " R "
terminal on the generator is impressed through
the regulator #2 terminal and through the field re­
lay winding, causing the relay contacts to close.
This connects the regulator #4 terminal directly to
battery through the field relay contacts, causing
the indicator lamp to go " O U T ." Generator field
current then flows from the generator or battery to
the regulator #3 terminal, then through the field
relay contacts and transistor TR-1 to the gener­
ator field winding.
As generator speed increases, the voltage
reaches the pre-set value and components in the
regulator cause transistor TR-1 to alternately
"turn-off" and "turn-on" the generator field volt­
age. The regulator thus operates to limit the gen­
erator output voltage to the pre-set value.
N O T E : A n ammeter type charge indicator is
used as standard equipment on conventional cab
models and is available as optional equipment
on tilt cab models. A voltmeter type charge in­
dicator is available as optional equipment on all
models.
ANALYZING CHARGING
SYSTEM TROUBLES
N O T E : Procedures for analyzing or checking
charging system trouble are explained previously.
Adapter (J-9782-3) may be used at the regu­
lator to facilitate checking circuits.
If trouble is located in the generator during
the test procedures, refer to the applicable gener­
ator section for corrective procedures.
When analyzing the system, make sure all
connections between the battery, junction block,
and generator are clean and tight, then remove the
wiring harness connector from the regulator and
connect the adapter between the wiring harness
connector and the regulator.
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK S H O P M A N U A L