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Page last updated July 17, 2008

 

 

Mercury Rectifier Troubleshooting

Rectifier testing and troubleshooting

If you are having problems with the charging system, you may need to test the rectifier for functionality. The test involves the use of a multimeter. The rectifier can remain in place, but all wires will need to be removed from the rectifier.

I have assembled a diagram to assist you and have taken several pictures. Please keep in mind that the rectifier I am using is faulty so most tests will fail. The correct reading is mentioned but the picture may show a faulty reading.

You can see the terminal to the left with each post identified using letters. Ground has been labled as (G) for simplicity and actually is the entire bottom plate. The tests involve touching the ground and the touching the posts.

Please refer to the lettering in order to follow procedures.

The rectifier takes Alternating Current (AC) from the stator (feeds the A and C terminal) and converts it to Direct Current (DC) and outputs the voltage to the B terminal marked with a "+" on both sides. The rectifier has diodes inside the plastic moulding to prevent juice from flowing backwards.

If you ever accidentally reverse cables on your battery, you may fry the rectifier.

How can you avoid the "accidental" reversal? Make sure you have a RED cable for positive and the POSITIVE terminal has a RED marking with a big "+" sign next to it. Some red spray paint may save a $50.00 repair job.

 

 

 

CAUTION: Make sure the battery is disconnected prior to servicing.

 

Here are the steps:

 

Ensure all wires have been removed from rectifier and battery has been disconnected.

 

  1. Place/set your multimeter to the 1000 ohmmeter reading (RX1K, R X 1000, etc). See picture below.
  2. Place the RED lead to the ground (G) and place the BLACK lead to A and C alternating. You should show continuity.
  3. Place the BLACK lead to the ground (G) and place the RED lead to A and C alternating. You should NOT show continuity.
  4. Place the BLACK lead to the terminal (B)) and place the RED lead to A and C alternating. You should show continuity.
  5. Place the RED lead to the terminal (B)) and place the BLACK lead to A and C alternating. You should NOT show continuity.
  6. If your results differ, then the rectifier should be replaced.

 

 

See page 2 for pictures

 

 

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