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The rectifier is a silicon semi-conductor device which allows currellt to flow in one direction only. lt is connected to provide full-wave rectification of alternator output Current.
The rectifier requires no maintenance beyond checking that the connections are clean and tight. The nuts clamping the rectifier plates together must not under any circumstances be slackened.
A separate nut is used to secure the rectifier and it is important to check periodically that the rectifier is firmly attached andI therefore well earthed.
When tightening the rectifier securing nut, hold the rectifier with a second spanner, for if the plates are twisted, the internal connections will be broken.
Testing the rectifier on the machine
(1) Disconnnect the Zener Diode by removing the straight Lucar connector with the Brown/ Blue cable from the 2 MC capacitor.
(2) Locate the snap connector junction for the Brown/Blue cable to the box and disconnect.
(3) Connect a D.C. voltmeter (with the 1 ohm load in parallel) with the red lead to earth and the Black lead to the Brown/Blue cable from the box.
(4) Locate the White/Yellow cable in the other snap connector junction from the box. and using a jumper lead connect the cable from the box to the negative (-) terminal of the battery.
(5) Start the machine and run at approximately 3.000 rev./min., and take a reading from the voltmeter. This should not read less than 7. 75 volts, which indicates the rectifier is operating satisfactorily. A lower reading indicates a fault in the rectifier which can be confirmed by a bench test.
(6) Stop engine before disconnecting the voltmeter.