Replacing The Resistance On The Voltage Regulator Shunt Winding And The Resistance Of The Current Regulator And Cut-Out Relay Shunt Windings - Fiat 411 R Service Manual

If still in doubt, repiace these resistances which are fixed to the base by rivets. Drtil the rivet head
first, then drive the rivets out with a punch paying attention not to damage the Wires soidered to the
pistes (12 and 13, Fig. 149). To prevent the current regulator core from rotating whiie removing and
refittina the resistances use tool A 127650 as shown in Fig. 157. The new resistances shaii be fastened
down zvith the screws, spring washers, and nuts specified tor the replacement.
The vaiue of the control resistance (8) is 136 to '14-4 ohm, that of the damping resistance (10) is 60 ohm.
Check that the air gap between the armature and the expansion edge of the current regalator core (at
position B-0 of Fig. 149) is 0,99 to 1,11 mm (-3.039" to 0.044"). To correct the air gap use tooi A 127051
on the fixed contact support (4, fig. T52} and check with a magnifying iens it the contacts are atigned
cerrectiy. The gap between contacts of the cut-out reiay shouid be 0,64 to 0,76 mm (0.026 to 6.030") and
the air gap measured on the expansion edge of the core facing the contacts (Axis A-A, Fig. 158} and
with contacts ciosed shouid be 0,25 mm £0,010").
Then toiiow test bench checks, reported on page 100, to ensure that the troubie has been compieteiy
eliminated and reassernbiy has not altered in any way the operation of the various parts.
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Fig. 'i5'!.- Control box GP'!/241'? withiool A12?B5U instailed Fig. 158. - Rear view of the control box.
to replace resistances 6 and 10, Fi9- T59- 1. Cutout reiay armature hinge - 3. Setting spring - 4. Fixed
5_ getting spring, suppmt tam} contact support tang -3?. getting Spring, support tang -
. roun .
Ftepiacing the resistance on the voltage reguiator shunt winding and the resistance of the current
reguiator and cut-out relay shunt windings ('7, 1'1, Fig. 159).
It the voitage setting of the reguiator has changed, that is:
-— reguéating voltage is low;
~— reguiating voitage rises to high values because out of controi;
the cause can be attributed to the resistance of the voltage regulator shunt winding (7, Fig. 159} which
can be aitered (short) or interrupted.
A coil short increases the absorption on the part at the voitage reguiator shunt winding (because the
resistance ts connected in series to said winding} and increases the puii on the armature resuiting in a
iower regulating voltage. Shouid the reststance he interrupted, the voitage regulator shunt winding does
no longer get across to the generator but remains Ensuiated.
Théfeififth as the flow of current is interrupted the core cannot putt the armature, contacts do not open
and the voitege, out of control, rises.
104