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LI 125 S2 1959 Rectifer/Regulator Problem

Technical help for Series one, two and three Lambrettas. Models include the Li, Li Special, TV, SX, GP, Serveta and API/SIL models

LI 125 S2 1959 Rectifer/Regulator Problem

Postby KatieW » Sun Oct 24, 2021 8:52 pm

I have 14.5 volt output from my rectifier/regulator, its a 1959 early series 2, with some series 1 bits.
Its a non battery version and i have just recommissioned her and ridden it for the first time
It blew both my front headlight bulb and rear festoon light.
Thankfully my brake lights were not affected but on closer inspection they were glowing very bright when operated.
The regulator is a I.M.P.E.A . Genova.
I wish to keep the scooter as original as possible as it has not been painted and is in exceptional condition for the year.
Does anyone repair Rectifier/Regulators or are they throw away at the end of their lives.
Any suggestions or does anyone have one in good condition.
KatieW
 
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Re: LI 125 S2 1959 Rectifer/Regulator Problem

Postby Andyf » Sun Oct 24, 2021 9:09 pm

are you sure it's not an upgraded 12V system?
Andyf
 
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Re: LI 125 S2 1959 Rectifer/Regulator Problem

Postby Warkton Tornado No.1 » Mon Oct 25, 2021 1:24 pm

As standard, your engine will have had six volt lighting, so something has changed. Perhaps you failed to mention that it has been modified to a 12 volt system.....

in any case, if you are now running 12 volts (no bad thing) then to regulate the 14.5 volts may be all you need. The common practice used to be to fit a zenner diode but that meant changing to positive earth. However, negative zenners are available, but there may well be better, less expensive options these days. Just be cautious of some of the Chinese products.

For my understanding, it would be great if you would clarify whether you want as OEM a six volt system, or, as seems sensible, a modified set-up with the reliability of points but with 12 volt lighting.
Warkton Tornado No.1
 
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Re: LI 125 S2 1959 Rectifer/Regulator Problem

Postby KatieW » Mon Oct 25, 2021 7:50 pm

Andyf wrote:are you sure it's not an upgraded 12V system?


I am very sure that all electrics are original 6V.
KatieW
 
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Re: LI 125 S2 1959 Rectifer/Regulator Problem

Postby KatieW » Mon Oct 25, 2021 7:52 pm

Warkton Tornado No.1 wrote:As standard, your engine will have had six volt lighting, so something has changed. Perhaps you failed to mention that it has been modified to a 12 volt system.....

in any case, if you are now running 12 volts (no bad thing) then to regulate the 14.5 volts may be all you need. The common practice used to be to fit a zenner diode but that meant changing to positive earth. However, negative zenners are available, but there may well be better, less expensive options these days. Just be cautious of some of the Chinese products.

For my understanding, it would be great if you would clarify whether you want as OEM a six volt system, or, as seems sensible, a modified set-up with the reliability of points but with 12 volt lighting.


This is an original 6V scoot with all original electrics on it. I would like to keep it OEM six volt.
KatieW
 
Posts: 14
Joined: Mon Mar 30, 2020 7:29 pm

Re: LI 125 S2 1959 Rectifer/Regulator Problem

Postby lofty » Tue Oct 26, 2021 11:02 am

often, the non-load, non-regulated voltage of even a 6v system will far exceed 6v.. so this seems possible to me..

the old regulators are quite crude and tend to be a bit flaky over time, but unfortunately it is not easy to get replacements as most people opt to upgrade to 12v these days..

best bet is to first check wiring and connections as per a diagram or manual for your scoot.. if you need a new regulator then its a case of checking shops/ebay/etc for someone with an old one of the same spec..
alternatively you can fit a modern 6v regulator in an old regulator case to give reliable voltage with classic look..
lofty
 
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Re: LI 125 S2 1959 Rectifer/Regulator Problem

Postby Warkton Tornado No.1 » Tue Oct 26, 2021 12:15 pm

Nobody should feel under pressure to change any element of their Lambretta, but from a safety aspect, we wouldn't run them on the OEM tyres, so that's the first flaw in any plan to keep totally original. Simply because points based 12 volt upgrades have been available from the 1960's, if not before, is a good enough reason for me personally, to use such systems. The additional safety benefits of lights that work with no engine running should not be overlooked.....

Anyway (stepping down from my soapbox) if you put an image of the rectifier required on this Forum, I am sure one of us will be able to help ;)
Warkton Tornado No.1
 
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Re: LI 125 S2 1959 Rectifer/Regulator Problem

Postby Andyf » Fri Nov 19, 2021 8:59 pm

lofty wrote:often, the non-load, non-regulated voltage of even a 6v system will far exceed 6v.. so this seems possible to me..

the old regulators are quite crude and tend to be a bit flaky over time, but unfortunately it is not easy to get replacements as most people opt to upgrade to 12v these days..

best bet is to first check wiring and connections as per a diagram or manual for your scoot.. if you need a new regulator then its a case of checking shops/ebay/etc for someone with an old one of the same spec..
alternatively you can fit a modern 6v regulator in an old regulator case to give reliable voltage with classic look..


Wouldn’t 14V keep blowing 6V bulbs? If not, why change bulbs when changing to a 12V regulated system? Or is that over-simplifying?
Andyf
 
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