And it let the smoke out

Trying to determine which came first the chicken or the egg.
Went for a ride the other day and about 2k from home the bike stated to act up. It would idle ok but when the revs were increased it ran like a hairy goat (I run normal points).
Struggled to get home and noticed my handle mounted GPS was not working nor my electronic assimilator, didn't think much of it at the time. When the bike cooled down stripped and cleaned the carby and reset the ignition timing, none of which were the issue. Found the battery very low so charged it over night and started the bike in the morning only to find when I put a meter across the battery, at idle was 12.5v at 3000rpm it was over 15V. So I now suspect the no name electronic regulator.
Fitted a brand new battery and the regulator behave as normal settling down to 14.2v at high revs.
So perhaps my battery went very high resistance or open circuit when I was out and about and the volts went through the roof?

So the question is what happen to the regulator output voltage if the battery goes high resistance or open circuit WHEN the motor is running.
I can understand that the bike will not start with an O/C battery and I also suspect that the regulator will not output and voltage until it see some sort of battery connected.

However I can assure you that the smoke was let out of my GPS which was evident by the black crater on the circuit board, same story for the electronic assym.

So recommendations please on a suitable regulator replacement that will behave itself under these fault conditions.

I only run the standard Norton dynamo not a high output one.

Cheers

" Trying to determine which came first the chicken or the egg. "

The EGGPLANT !

I can vouch for the Boyer Powerbox with built-in assimilator - I haven't done vast mileages on mine, but it's neat, and not overly expensive here in the UK
My years of experience with Boyer stuff is that it's rugged and dependable.

http://www.boyerbransden.com/power_boxes.html

Perhaps other users can share their experiences with these?
As to what caused your issues? Just a guess, but it sounds like an intermittent diode short which lacks the decency to go hard over and be detectable!

Either that or you have a Ducati regulator, which do this sort of thing for fun :roll:

Ducati that's it !!.
It will be the ducati valve stem oil seal I put in the in the tacho drive that has tainted my electrics.

Starting to think that perhaps there might have been an earth issue.
This explanation is a bit long winded but I think it fits the problem.

The regulator has 2 AC wires (yellow) and only one +V out (red) it relies on the metal housing of the regulator for the -negative (earth) return, yes I run -ve earth.
If the regulator earthing connection was doggy then the internal control reference inside the regulator might float high (actually low see later), resulting in an increased output voltage.
However with a good battery, it (the battery) would happily accept more current (as it has a low internal resistance) and thus it would keep the voltage lower (probably start to boil).
This due to the dynamo having limited output current capacity, the voltage would drop as the current goes up and vice versa, this is how the standard Zenner setup works, the zenner does not do any work until the current required to charge (or load) drops and the voltage starts to increased, then the zenner conducts and clamps the voltage and sinks the extra current.

With the electronic regulators under normal operation when the battery is charged the output voltage would be clamped by the internal reference (it is actually a small zenner) to the desired level 13.8-14.2v.
Now if the battery failed and went high resistance or open circuit it would not be able to accept any or little charge, then the voltage should be clamped by the internal reference.
That is unless the earth of the regulator was not at earth potential then the reference voltage would be the reference minus the earth potential, lower then it should be.
This would tell the regulator to increase the charge voltage as it incorrectly thinks the battery is low and needs charging. With a faulty battery it would not accept any current so the voltage would rise. This rise would depend on how much the regulator earth had risen, and in my case enough to destroy on board electronics.

This may explain why the battery eventually failed and why things look normal with a new battery fitted (a time bomb until it also fails eventually)

I have now upgraded and fitted an earth wire direct from the metal case mounting stud of the regulator direct to the battery.

Time will tell but I think I will replace the regulator any way.

Cheers

Is your regulator mounted on a proper heat sink? Norton zenners are mounted on the alu Z plates and older Brit bikes used actual finned heat sinks to dissipate the energy as heat. If it occurs again try turning on the headlight to take the overload to see if it helps.

2 yellow wires...

Definitely Italian :cry: , and possibly *actually* Ducati :shock:

I mounted my powerbox in a 2mm thick alloy plate onto the gusset at the back of the main frame spine by the mudguard. Ideally it should be out in the air flow, but a thing of beauty they aren't.
Early Fastbacks have a large circular alloy plate mounted in front of the LH sidepanel for the Zener - not too pretty either.

I had issues with one of my Ducatis blowing bulbs, but never 'on the road'. I finally discovered the PO had wired it to isolate the earth on switch-off, thus removing the return path and allowing unregulated voltage to find its way through the system. That got sorted, and last year, on my way to the 'Chumley' Pageant of Power (tickets kindly donated by Mick Hemmings) it went kaput again. I run a DMC ignition, and it would tick over just fine, but would cut out as soon as the revs rose. The DMC has OV protection built-in, so it was looking after itself. If I'd just removed those f&%$ing yellow wires I could have got there on the battery alone... as I found out after I'd unloaded it from the recovery truck back at home :evil:

As it was I missed the show due to Ducati's mid- '70s nasty in-house electronic boxes - should have gone on the Commando!
A mate had battery health issues on his Guzzi 1100 Sport at Cadwell last year - when we got the tester on it, the regulated voltage wasn't going above about 12.5V - yet another of the same style regulator, but 30 years younger, and still utter carp!

Whatever the reason (and I agree that diodes are unusual for intermittent failures) the answer must be the same :lol: