66 Atlas battery discharge/shorting

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Mar 29, 2013
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Hello all - I'm looking for some suggestions to remedy my shorting /discharge issue. I have all original equipment on the bike (magneto, zener diode and rectifier) and I get an arc crossing when I attach the battery terminals. The amp gauge whips over to max. No lights are on, I've tried disconnecting the Zener diode and rectifier from the circuit- no change. I disconnected the 2 wires from the alternator - no change. Any wiring that I can get to seems to be in good shape (new harness a few years ago)

Any suggestions on what to try next? I don't want to start buying a bunch of parts that aren't necessary. Thanks for any help.
 
Finding a short circuit is best done by the 'divide and conquer' approach. This entails dividing the electrical circuit into parts by removing a connection at a strategic point. Then, touch your battery into the circuit, if no arc, the problem is in the bypassed part. Make sense?

Your wiring diagram is most likely the last in the list shown here:


I would first remove the brown/white (NW) wire at the ammeter. Then connect your battery. If you get an arc or abnormal discharge, the problem is in the horn or stop light circuit. If no arc, that part of the system is good. Disconnect the battery, reconnect the NW wire at the ammeter.

Next, go deeper into the system. Following the wiring diagram, disconnect the NW wire at terminal 2 on the Lighting Switch. This isolates the Zener and rectifier. Continue the test when you connect the battery. Keep going deeper until you isolate the bad part of the system.

Report back.

Slick
 
Thanks for the quick replies. I went through the process suggested and found no spark when ammeter disconnected and followed that through to the diode. When disconnected - no spark. So I guess it is safe to assume the diode has gone?
 
It would seem to be true ...... HOWEVER, DO YOU HAVE REVERSED POLARITY ON THE BATTERY? You do know, Nortons are positive ground. Should your battery be connected with neg. ground, the results you found would be predictable.

Report back ..... is your battery connected with positive ground?

Slick
 
Hello Slick - yes I have been observing all things positive. Ground that is. Actually the battery has been taken out and I've been conducting the testing by connecting the battery each time, to positive ground. Thanks for the additional info.
 
How is it that your original post said you disconnected Zener and rectifier with no change?

Remove conection at the Zener ONLY ..... then do the test. If test passes, then Zener is highly suspicious. If test fails, then rectifier is suspicious (note from wiring diagram, Zener and rectifier share a connection).

Report back

Slick
 
I've done the test with the Zener disconnected and the rectifier connected and the the test passes. Not sure why it didn't show last time. So it does seem to be the diode.

again, thanks for the input.

Steve
 
It would seem to be true ...... HOWEVER, DO YOU HAVE REVERSED POLARITY ON THE BATTERY? You do know, Nortons are positive ground. Should your battery be connected with neg. ground, the results you found would be predictable.

Report back ..... is your battery connected with positive ground? Slick

+1.
Can I ask, have you connected the battery to negative earth at all?
 
If yours has been modified to another configuration like positronics for example, this might be the case but mine is strictly stock using mag, rectifier, alternator and zener.
 
Do you have a 2MC capacitor (usually left side aft of battery box ,Blue cylinder in a spring mount)?. These do take a belt of current to charge up.
 
hello Norton Bob - nothing like that on this bike or on the wiring diagram. What would it be used for?
 
With a 2MC you can start an alternator and battery ignition bike with a dead battery. Only needed to disconnect the battery. Some bikes have an emergency ignition switch position for that.
From experience I know it works with both points and Boyer.
 
Well - I found a working used Zener Diode at Motoparts in Edmonton and received it today. Carefully grounded the unit and plugged it in and - voila! I have charging, no shorting out and the Atlas runs like is was supposed to.
Thanks to all who replied to my query, especially texasSlick! It's good to hear my bike bark again!
 
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