Honda CB450 1968 Service Manual page 132

5. 4 POWER CIRCUIT
There are several rectifying circuits used in auto-
mobiles. In both the CB 450 and CL 450, the same
type rect ifying curcuit is used, the bridge circuit
shown in Fig. 5. 36. In this sy stem, a greater num-
ber of selenium wafer s are used, however, the fea-
ture of this type is that a full wave rectification
can be achieved rather than a half wave rectifi-
cation as is the case with other systems . ( Fig.
5.
36)
Heat will have great effect on the life of the
selenium rectifier ; it should never be exposed to
heat greater than 30 °C (86. 0°Fl for any great
length of time. Further, excessive current should not
be allo w ed to flow for any extended period, like-
wise, voltage exceeding the capac ity should not be
permitted to flow in the reverse direction as this
will puncture the rectifier. However , insulation
will quickly form over the punctured area, but
with repeated puncturing, the effective rectifyi ng
area will be reduced and will eventually result in
the overheating of the rectifier. Therefo re, in order
to handle the voltage generated by the coil, the
wafers must be increased to provide for sufficient
reverse capacity.
Note:
Handling the selenium rectifier
l. Do not allow water to get on the rectifier,
make a wrong wiring connection or subject it
to abuse. (selenium rectifier usage is semi-
permanent)
2. Using the rectifier without any load connected
such as without the battery, will cause a high
voltage generated in the coil to flow in the
reverse direction and cause puncturing of the
rectifier.
3. If this condition is permitted to continued
for a long period, the rectifier will be com-
pletely destroyed.
4. After a long period of usage, the rectifier
will age.
When this happens, the internal resistance will
increase, output voltage drops and the rectifier
will heat up.
The major cause of aging is exposure to high
temperature.
Wh en the temperature of the rectifier exceeds
70° C l 158 . 0°Fl, the aging is greatly acceler -
ate d, therefore, atte ntion should be given to
prevent the rectifier from overheating, the rec-
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Fig . 5. 36 Full w ove rectifrcotion
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Battery
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