Repair Instructions; Cover Replacement; Replacing The Regulation And Damping Resistances - Fiat 411 R Service Manual

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Finally, if the trouble is not due to one of the causes described at paragraphs a), b) and c), look for it in
the battery, control box, or generator. To find out whether the trouble is due to the battery replace the
existing one with a new one discharged so that it the output still goes to the maximum evidently the fault
is in the battery. it not, look for it either in the control box or generator by shorting momentarily the
terminal 67 with the 51 and increasing the generator speed. Should the output, previously absent or very
low, either reach a set value or increase, the trouble is due to one oi the following:
- low current or voltage regulator setting;
Fl - 4 current or voltage regulator contacts oxidized;
~~ undue resistance, interruption oi the generator field winding or inside the unit.
Otherwise, look tor trouble in the generator.
REPAIR ¥NSTRUC'£'iONS
As a rule it is preferable to repiace the control box rather than repairing or acliusting it, therefore only
exceptional cases may justify handling it. The repairs which can be done. provided that it has been
found for sure that it is the cause oi trouble, are: repiacing the cover, the additional resistances ('i', 11,
Fig. 159}, the damping resistance (10), and the regulation resistance (6).
The spares are furnished in special containers to avoid contacts with foreign material.
Most of the faults oi the trouble, particularly the more serious ones such as excessive consumption or
welded cut-out relay contacts, oxidized or pitted voltage or current regular contacts, coil shorts and wind-
ing overheating, are due to faults outside the unit and particularly to the same faults of generator com~
ponents (field winding resistance altered, wrong brushes, faulty cables, etc.).
Therefore, the repair man should not content himself by replacing the control box, which has anyhow
a high factor oi safety in operation, but rather check the generator and the whole charging system.
Cover replacement.
Shouldlthe replacement be due' to bruises or warping we suggest to check the control box prior to
replacement, according to the testing procedure of page 100 and following.
When replacing the cover check the seal gasket and place spring washers under the screw heads of the
base, then tighten the screws until the two ends of the washers come in contact. Finally, apply a paint
seal on the head oi one screw.
-»=,
Replacing the regulation and damping resistances (6, 1&3, Fig. 159).
Here follow the causes and their respective consequences in case of wire interruption or shorts of the
resistances (5, 10, Fig. 159):
a) control voltage low or very low; a) oxidized voltage and current regulator contacts;
b) control voltage rising because out of control; h) voltage regulator contacts stuck because of
self-Welding;
c) control current rising because out of control; c) current regulator contacts stuck because of
self-welding;
d) control voltage very unstable particularly at ti) temporary sticking of the voltage regulator
high generator speeds. contacts.
Paragraphs e), lo), c) concern the control resistance, paragraph cl) the damper resistance.
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