sat nav JEEP DJ 1953 Service Manual

'Jeep*
UNIVERSAL SERIES SERVICE
MANUAL

H
long as the circuit values allow the voltage to build
up to the operating voltage.
The
electromagnet of the voltage regulator unit has

a
winding of many turns of fine wire and is con­
nected across the charging circuit so that the sys­ tem voltage controls the amount of magnetism.
The
contacts of the voltage regulator unit are con­
nected in the generator field circuit so that the field

circuit
is completed through the contacts when they

are
closed and through a resistor when the contacts
are
opened.

When
the voltage rises to a predetermined value
there is sufficient magnetism created by the regu­

lator
winding to
pull
the
armature
down.
This
opens

the contacts and inserts resistance in the field
cir­

cuit
of the generator thus reducing the
field
current.
The
generated voltage immediately drops, which
reduces the
pull
on the
armature
to the point where
the spring closes the contacts. The output again

rises
and the cycle is repeated.

These
cycles occur at high enough frequencies to
hold the generated voltage at a constant value and

will
continue as long as the voltage of the circuit
is high enough to keep the voltage regulator unit

in
operation.
With
the addition of a current load great enough to lower the battery voltage below
the operating voltage of the unit, the contacts
will

remain
closed and the generator
will
maintain a
charging
rate as limited by its speed or the current

limiting
regulator.

Due
to the
effect
of heat on the operating
charac­

teristics of regulator windings it is necessary to
compensate for the changes in coil resistance when
the regulator is operating under varying tempera­

ture
conditions.
This
is accomplished through the
use of a nickel iron magnetic by-pass on the volt­
age regulator unit.
This
shunt by-passes
some
of
the magnetic flux when the unit is cold and allows most of the flux to act on the armature when the

unit
is hot.
Thus
when the coil is hot and not as
efficient, the magnetic shunt reduces the amount of flux needed to vibrate the armature.

The
compensation is usually more than enough to

offset
the changes in regulator coil resistance due
to heat. The excess compensation allows the regu­

lator
to operate at higher voltage under cold
operating conditions than under hot conditions.
This
is necessary as it requires a higher voltage to charge a battery with its internal resistance in­

creased
by low temperatures.

H-45.
Current-Limiting
Regulator

The
function of the current-limiting regulator is to limit the output of the generator to its maxi­

mum
safe output.

The
electromagnet of the current regulator unit
consists of
a
winding of heavy
wire
that is connected
in
series with the generator output. When the gen­

erator
output reaches a predetermined value, the
current
in the winding produces enough magnetism
to overcome the spring tension and
pull
the
arma­
ture
down.
This
opens
the contacts and inserts re­
sistance in the field circuit of the generator.
With
the field current reduced by the resistance, the
generator output falls and there is no longer enough
magnetism to hold the contacts open. As soon as
the spring closes the contacts, the output rises and the cycle is repeated. These cycles occur at high
enough frequencies to limit the output to a mini­
mum
fluctuation.

H-46.
Preliminary Inspection

a.
Wiring—Check
the wiring to see that it is prop­
erly
connected to the generator.

b.
Generator
Performance—Make
sure the genera­
tor operates correctly without the regulator in the
circuit.
Remove the armature and battery leads

from
the regulator and connect an ammeter be­
tween them. Remove the field lead from the regu­

lator
and while operating at idle speed touch the
field
lead
to the regulator base. Increase the speed slowly noting the charging rate.

CAUTION:
Do not increase the output above
the rated output of the generator.

If
the generator output
will
not build up inspect
the wiring harness for shorts and
opens
and remove the generator for an overhaul. To check the genera­
tor circuit when a suitable ammeter is unavailable,

Fig.
H-19, disconnect the armature cable at the

regulator.
Connect one lead of
a
12v
test
lamp to the regulator terminal marked "armature" and with
the engine running, ground the other lead. Should
the
test
light
fail
to
burn
there is a fault either in the generator or regulator. To localize the fault, discon­
nect both the
"Field"
and
"Armature"
cables at the generator. Connect a wire from the
"Field"
ter­
minal
to ground and use a 60 watt, 110 volt
test

lamp
to ground the
"Armature"
terminal. If the
generator is charging satisfactorily the
test
lamp

will
glow
at approximately 1500 rpm. engine speed
and
the fault
will
be definitely localized in the
regulator.

c.
Incorrect Regulator—Make sui he regulator
is the correct type for use with the generator.

d.
Battery—Check
the specific gravity and termi­

nal
voltage of the battery. If the \ ttery is not up
to specifications substitute temporarily
for
test
pur­
poses
a fully charged battery of the same type and
capacity.

e. High Resistance Connections—Inspect the
wir­
ing between the generator, regulator and battery for broken wires and high resistance connections.

Pay
special attention to the ground connections at
all
three units. Connect a reliable ammeter with 1-ampere graduations in series with the regulator

B-terminal
and the lead removed from this
terminal.
Run
the generator at a medium speed and
turn
on the lights or accessories until the ammeter shows a 10-ampere charging rate. At this charging rate
measure the voltage drop between the following
points using an accurate voltmeter graduated in
,1-volt divisions. The voltmeter should not show

a
reading above the maximum noted.
Generator
"A" terminal to regulator
"A"
terminal
—.1-volt maximum.

Generator
"F"
terminal to regulator
"F"
terminal
—.05-volt maximum.

Battery
terminal to regulator "B" terminal— .1-volt maximum.

Regulator
ground screw to generator frame— .03-volt maximum. 191