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Discussion Starter · #1 ·
Hi guys i am restoring a bridgestone motorcycle right now and i have been going through the electrical trying to figure whats good and bad and it seems that the selenium rectifier is bad on it and it really hard to find a new one or a used one that works, i was wondering if there is something that could replace it and it is a 6 volt system.
 

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The rectifier itself likely doesn't care about the system voltage. The regulator however, does. Is that what you are concerned with, or perhaps both functions are combined?
 

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Vintage Rider
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My book shows it uses a half wave rectifier. Aftermarket units are readily available at low cost and will be more efficient than a selenium unit. You can use a full wave rectifier and just hook it up with two terminals. Just make sure it's installed in the correct direction. Current flows to the battery. The battery is the regulator on your bike so you need to have a good battery that can accept the output from your magneto without over voltage destroying lights and possibly other electrical components. Have you tested yours with an ohm meter yet? Here's an example of what you will find. 2 (Two) Diodes, Inc. 100V 50A Full-Wave Rectifier Bridge P/N: GBPC1501 | eBay
 

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Discussion Starter · #5 ·
So i do have a good battery on it, but what would i exactly have to buy to replace the old rectifier, like could you guys give me an example of what to buy because I haven’t the slightest clue.
 

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Discussion Starter · #6 ·
Sorry guys I didn’t see the link, what does that link go to a half wave rectifier or a full wave.
 

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Vintage Rider
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This halfwave unit should work, although it has 12v regulation it wouldn't come into effect, nor hinder charging.
You can also use a full wave bridge rectifier by using only 2 of the 4 terminals.
 

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If your machine is configured like the Bridgestone 90 schematic you posted, it appears that it had no regulator at all, and what looks like a single diode to rectify the pulses from the magneto. That diode is called a "silicon rectifier" on the schematic. Why do you say it's a selenium? How many terminals does it have?

If your system is wired like the schematic, I don't see how you would benefit from a three or four terminal device unless you lifted the ground connection on the magneto. But I'm not quite understanding the schematic either, the dashed wire shown as supplying the ignition coil doesn't seem to terminate?

If you want to stay with a 6V system, you can protect the system from overvoltage with a simple zener diode shunt rectifier, which is what this appears to be:

This, on the other hand looks to be a half wave rectifier only, without any regulation:

What are the various positions on the main switch for?
 

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Discussion Starter · #10 ·
I know its a selenium because thats what it says it is in the manual and the regulator on the motorcycle is the battery, and i dont know much about the wiring on this as ive had it hot wired just to get it to start and I’ve never had anything hooked up until now.
 

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Discussion Starter · #11 ·
I just wanted to see if that 6 volt rectifier that i put a link in for would be the same as the original selenium rectifier from 1964, just newer.
 
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