Why did a short burn out all my light bulbs?

[Guest]

I had an unfortunate situation where the wire to my coils rubbed through. It looks like the fuse (ATO style) did not function properly and after it failed, the bit of metal that was left bent to complete the circuit again. Or possibly a 20A fuse was too much? The PO installed it.

All the light bulbs burnt out (everything is on a single fuse), and I'm trying to figure out why. I know it's because of the short, but I'd like to know why a short would cause the bulbs to burn out when the shorted wiring path does not go through them. I have a decent knowledge of basic DC wiring, but I'm obviously missing some bit of information here.

[tom203]

Did this happen when you were riding? Anyways, sounds like you need to check charging system .If main fuse blows, this disconnects battery from harness, and R/R can get bewildered and can raise system voltage to > 15 volts, so bulbs start burning out. But since PO installed a 20 amp fuse, I'd suspect he had problems too.
You see this...

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A20

[Killer2600]

What tom said, system voltage spiked high and blew your bulbs.

[Eric]

Yes, it was while riding. I checked the voltage after getting everything put back together, and it got up to 16+ volts at 3000rpm, so there is definately a problem there.

I'm not sure what model of r/r it is, so maybe someone can help identify it. There's no markings on it that I can find.



The connector on the left with the brown and green wires wasn't connected to anything when I purchased the bike a year ago, and everything has been working fine so I didn't give it much thought. Anybody know what they are for? The normal 5 wires are all on a separate connector.

[tom203]

Looks like something off early 80's Yamaha (white stator wires plus brown and green seperate wires). It's likely designed for a field controlled alternator (auto type with brushes)- brown and green go to field circuit which your bike doesn't have. I'm sorta surprised it worked, but not surprised it has a high output voltage - must have a designed in max voltage in case field circuit fails (or in your case not connected!)
You need a correct R/R real quick.

[Eric]

I'd been considering purchasing a compufire unit for awhile now, I guess it's time to pull the trigger! Thanks for all your help!

[Bookmon]

have you checked the bike spec pdf's at places like Bike Bandit or GSsuzuki.com? with your year and bike size spec numbers, you should be able to find A- aftermarket rectifyer or B- used rectifyer. for my 450 GSA, had to settle for used, but it's worked fine for years.

[OldVet66]

With the evidence weighing in for the series R/R's, there is little logical point on playing Russian roulette with the old shunt R/R's.