Testing a rectifier on a Johnson 110

[camalot]

Hi guy's

After doing a search and finding some very useful info how to test a rectifier, I feel that I have found my problem. I tested the ohms on the yellow, yellow /gray wires and get a reading both ways so I think I can safely I need a new one.

But my question is about the diode setting, I set my meter to diode test and got no reading at all. Would that be right, if the diodes have fail it would not read either way.

Here is the very useful info I found and how I tested the rectifier.

Using the K.I.S.S. method with a $8.95 volt/ohm meter, the following would tell the tale.Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction. Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other. Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires. Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier.

Cheers Paul

 

[Joe Reeves]

Re: Testing a rectifier on a Johnson 110

(Small Rectifier Test)
(J. Reeves)

Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction.

Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other.

Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.

Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.

 

[camalot]

Re: Testing a rectifier on a Johnson 110

Thank you Joe!!

It was your posting that sorted me out, and reading the above post and using the diode setting just confirms what the ohm readings.

Thanks Paul