When Lights Just Don't Wanna Come On

[speedfreak]

Hopefully this will help someone down the road who isn't trained in electronics - cause I am and it still took me a couple of hours...

After doing all the paint and "prettying" of the beast, it was time for the first run-up. Kicked it over 3 or four times, then remembered to put the ignition on (my crowd was amused by this, of course). Next kick up she fired. Life... Fuel - good. Oil - meh (see my other post). Electrical - turn sigs okay, then...

I have modified the control switch on my project to allow the lights to be turned off (stock in Canada is running lights mandatory - so shhhh). When I hit the switch to turn on the headlight it went on - like a super nova! One flash and nothing. Hmmm... Off goes the headlight switch, but now the turn sigs are iffy. They look like they just don't wanna come on. One terribly weak flash, followed by regular but very weak flashing.

Before I go further I should note that I've got a large capacitor instead of a battery, so what goes here doesn't necessarily apply with a battery...

Headlight is now garbage - no low beam. So I check voltage - 14.4V. Great. Try turn sigs - same half-ass falshing. Check voltage with lights on 6V. Strange... Lights off and back to 14.4V. So I start chasing. Where is the partial short. What in my turn sig lines is killing the voltage. And... nada. Everything looks fine.

Then I have my a-ha moment. Back to first year electronics. If I don't have current capacity - it's cause I ain't making it. And where does the charge come from - the rectifier! After checking the legs it turns out it was only rectifying half-wave. One leg was shorted. Half-wave rectification will still get to 14.4V when there is no draw, but with lights on it's only charging half as fast.

Ripped the rectifier and regulator out and got a tympanium combined unit. Works like charm. Everything is nice and bright - excpet that I haven't got my new headlight yet... So we'll see how that goes.

If you had a battery, like most do, this would have presented itself dfferently. You may not have known for some time. It would have charged the battery (slowly) when everything was off, but would have drained it when lights were on. Eventually you'd have a dead battery and no idea why.

Perhaps it would be obvious to some, but I was happy with myself for not just swapping parts till it went away, but for diagnosing it down to one leg on the rectifier. Now if I can just stop stripping bolts on the oil pump (like I said, see my other post).

[Willie]

This has probably been covered before but I think its more efficient to respond to your post vs searching elsewhere for the answer. At least that's how I'll rationalize my asking vs admitting my laziness.
Do you know if the tympanium combined unit can be used to replace the separate reg/rec in a Buffalo? If so, how much does the units go for?
FWIW, I'm keeping the battery.
Thanks,
Willie

[Suzukidave]

Oregon makes a nice combined unit Reg / Rec for the GT750 http://www.oregonmotorcycleparts.com/index.html" onclick="window.open(this.href);return false;

[ConnerVT]

Do you know if the tympanium combined unit can be used to replace the separate reg/rec in a Buffalo?

The Tympanium can only be used on bikes with permanent magnet alternators. The GT750/GT550/GT380 use electromagnet alternators, which need a different type of regulator.

http://www.oregonmotorcycleparts.com/Reg_rec_units.html" onclick="window.open(this.href);return false;

[Alan H]

Sounds like the capacitor charged up and turned your dip beam into a strobe (once).
Maybe a poor contact somewhere didn't allow the voltage to be regulated properly and blew the bulb with a high voltage spike, then took half the rectifier out for good measure.