Blown fuses

kingcole · Nov 9, 2014

I am a new subscriber to A/N and have had my 1972 Norton since 1976. I used my Norton to commute into London 40 miles each way every working day for eight years. In 1984 I decided to park the bike in the garage and go by train due to being constantly cold and wet because of the unpredictable English weather and so my Norton was abandoned and due to work load and moving home it has not been ridden or even looked at for over 30 years. I moved from England to France in 1993 and of course the Norton came with me and has rested in the corner of an old French barn up until 2013 acting as a shelf. Free time and some motivation from an Indian Chief owner has prompted me into action to do something about my long lost friend and so a renovation is now in progress. All is going well with the mechanical side as I am an engineer by trade but I am having problems on the electrical side with constantly blowing fuses when trying to connect the battery when there is nothing switched on or connected, I have changed the rear half of the wiring harness as the front half and lighting circuits are all in good condition, all the colour codes of the wires match so there is nothing evident out of place. I am awaiting delivery of some new electrical parts to try to eliminate the problem ie. Zener diode, rectifier, capacitor etc. So if I can't find a solution I will be picking the brains of our educated forum..
Regards King cole

texasSlick · Nov 9, 2014

Do you have a VOM and know how to use it?

Remove the battery, connect the VOM (ohms function) with the same polarity as the bike, I.e. if the bike is positive earth, connect VOM positive lead to earth.

Now divide and conquer.... open bullet connectors to isolate (divide) the harness into segments. Remove or disconnect any device you may suspect, such as Zener or rectifier. With nothing switched on, and the other lead of the ohm meter connected where the fuse meets the main circuit, your ohm meter should read open circuit. If not, continue to isolate and look for a cause. Re-connect things one at a time, checking the ohm reading as you go.

Ask for more help if you discover something suspicious.

Slick

concours · Nov 9, 2014

Hi kingcole, welcome to the forum. A romantic motorbike story... Please, forgive if some of the Q's are too basic, just getting a feel for the bike, your skills, etc. tell us more about your skills please. 30 yrs., long time, you remembered the bike is positive earth, yes? Any damage to the cycle parts? Rear stoplight switch get mashed while moving/storing? As mentioned, a good start is to disconnect as much as you can, then begin plugging things back in. When the fuse blows, you've found it.
Any chance you can post some good close up images of the battery/electrics area?

kingcole · Nov 10, 2014

Thanks for your reply Texas slik I will be giving you an update when all my new parts arrive... King cole

kingcole · Nov 10, 2014

Hi concourse,
Many thanks for your helpful information, I will give an update of my progress when my new parts arrive and maybe a bit more of my history..
Regards King Cole

concours · Nov 10, 2014

kingcole said:
I am a new subscriber to A/N and have had my 1972 Norton since 1976. I used my Norton to commute into London 40 miles each way every working day for eight years. In 1984 I decided to park the bike in the garage and go by train due to being constantly cold and wet because of the unpredictable English weather and so my Norton was abandoned and due to work load and moving home it has not been ridden or even looked at for over 30 years. I moved from England to France in 1993 and of course the Norton came with me and has rested in the corner of an old French barn up until 2013 acting as a shelf. Free time and some motivation from an Indian Chief owner has prompted me into action to do something about my long lost friend and so a renovation is now in progress. All is going well with the mechanical side as I am an engineer by trade but I am having problems on the electrical side with constantly blowing fuses when trying to connect the battery when there is nothing switched on or connected, I have changed the rear half of the wiring harness as the front half and lighting circuits are all in good condition, all the colour codes of the wires match so there is nothing evident out of place. I am awaiting delivery of some new electrical parts to try to eliminate the problem ie. Zener diode, rectifier, capacitor etc. So if I can't find a solution I will be picking the brains of our educated forum..
Regards King cole

A free download of the workshop manual, complete with electrical schematics: http://classicbike.biz/Norton/Repair/70 ... mmando.pdf

Chili · Nov 10, 2014

Hi
Sorry for being too basic( if not the problem) but do you have the battery connected correctly ie positive earth, this could keep blowing fuses.
Peter

Blown fuses

kingcole

texasSlick

concours

kingcole

kingcole

concours

Chili

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