LCGB Forums

Hi Please can anybody help, Rebuilding a 1967 SX150, Mugello 200, Varitronic 12volt upgrade, Scooter is up running, but keeps blowing bulbs, Italian import, no battery
All the upgrades are new parts, any suggestions?

You've either connected your regulator incorrectly or it's knackered.

Or you keep putting 6v bulbs in

Thanks, Used 12volt Bulbs and checked the wiring, must be the regulator,

Regards David

Mine has blown lamps since I've had it when you give some - (tuned Imola).

Digger wrote:Mine has blown lamps since I've had it when you give some - (tuned Imola).

Well in that case either you've got a similar problem or the regulators are poor. I'll have mine running in few weeks when I get back from work; if mine blows bulbs regularly I'll be looking for a solution, probably a different type of regulator or at least a voltage limiting device in the headset.

My initial guess would be that if you have led rear lights, then the others would blow more regularly.

you are fitting 12volt bulbs in it ! have you checked your connections are right, my own scooter revs to 9000 rpm and does not blow bulbs !

Hi,

Wiring is correct, I've just had tested the output from the regulator, when revved the meter is reading almost 19volts.

This is a new Veritronic upgrade purchased from Cambridge Lambretta. I will ring them on Monday for a replacement. All the bulbs are 12volt with standard configuration, ie no digital.

Hi Joespeed,

Just noticed your address, I live in Monk Fryston, not far from you, Are you in a Scooter club. This is my first Scooter rebuild, SX 150, 1967, used to have a GP, back in the day! Would be interested in joining a Scooter club, any suggestions.

Regards David

Selby Moving Targets......

i m not far from selby and do ride with the club,, what did cam lam say?

Hi,

Regulator replaced, still blowing bulbs, checked and rechecked wiring, all seem OK, earth wires are all in place and reading fine. Scooter is starting and running no problem.

Lights are all working on tickover but blow if I increase the revs. Rechecked headset wiring all seems ok. It's colour coded so not sure what the problem is. One thing I have noticed is that the replacement loom, CASA has 1 wire less than the original, the Purple wire is not present in the new loom, could this be the problem? Horn works OK.
My get an election friend of mine to take a look.

Anybody have any ideas?

Just seen this thread, must have missed it.
So regulator no1 was reading 19V output, that's way too high.
What's the new regulator voltage?
The regulator does have a good earth and a good earth to the engine from the frame?

The earth is good all linked together, and reading OK, not checked the regulator, will do that, just seams strange to have 2 faulty regulators, too much of a coincidence.

To be perfectly honest I'm not an electrician, so I'm a little bit out of my depth, so i'm thinking it's something that I have not wired up correctly, although i'ts simple really

the headsets colour coded, which I have followed. The only difference I can see is the loom is missing a wire. I am not using the junction box and the replacement loom was recommended for an electronic ignition, for a series 3 Lambretta, could that be the issue?

I will check the regulator, and may try running an extra wire.

Thanks David

Lightybob wrote: just seams strange to have 2 faulty regulators, too much of a coincidence.

My Thoughts exactly.
I would check the regulator is connected correct as they have different configurations on the Varitronic regulator.
Bulbs blowing screams over voltage to me, and this is usually down to what the regulator pumps out 99.9% of the time.

Yes, it's definitely over Voltage because on tick over or low revs the lights are ok, as I rev they get brighter and then blow. The wiring is as the instructions, apart from the missing wire, although I am not sure what difference that makes as the lights are working, even the brake light! {untill I increase the revs}. I may try a different make, the BGM one looks compatible, when comparing the wiring diagrams. BUT I do not think 2 regulators are faulty.

Will keep you posted.

Thanks

Is it wired as per these instructions, attached? (Pic1)
If so, I can see the earth (pin 2) is the blue wire from the stator. The blue wire earths onto the stator plate (Pic 2)
Try earthing pin 2 to the bike frame/wiring loom. It would definitely appear the regulator is unable to dump the excess voltage down to earth, for some reason.

Just to clarify how the basic AC system is regulated, here's a simple diagram.
To the left, your stator. In the middle the regulator. The circle with the cross is the bulb(s)
Note how the regulator needs to be well earthed to dump the overvoltage.

as nelly has shown a nice easy to work out diagram,assuming you have good earths everyware as cam lam sugguest in the wiring diagrams,do not wire the lights on the scooter use the 'nelly diagram' to wire some stop tail bulbs up externally (cheap bulbs -scrap yard rear light bulb holder) and try again,
i still think the regulator is at fault! the main stator coils may be incorrect also! what did cam lam say?
if your still in doubt tel 07711062937 i'll take a look for you!
regards

joe


do you have a voltage gauge/meter

Thanks for all your help and advice, I will follow your suggestions and let you know how I get on.

Once again thanks.

Regards David

Sorted! It was the regulator, fitted a new BGM regulator and all working fine. Thank you all, especially "Nelly"

Regards David