Change out old regulator and rectifier for new combined one - how hard?


New member

Feb 2, 2020
Hi All

i have an old but reconditioned B1500. looking at the charging system it has a bundle of ancient components which I fear at some point will fail. See pic which I think shows a separate regulator, rectifier, diode and something called a control unit.

I wondered about what it would take to upgrade these to a more future proof modern system and believe I have located the parts here

closest wiring diagram I can find that looks like what I have

however these new parts look nothing like the parts to be replaced so trying to match up the cables is hard and it is not that clear which old parts are now redundant E.g control unit still needed?

anyone done this or something similar who can point me in the right direction?




Well-known member

Apr 2, 2019
I had a look at the wiring diagram and replacing the 'rectifier/regulator' unit is easy. Any of the 'B&S 15 Amp' units would work,with minor rewiring of the tractor. On the B&S unit , the 2 outside(yel) wires go to the dynamo (AC) and the center (red) goes to the switch-->battery. Unit MUST be grounded. The case is 'ground' for the electronics inside. This module has been out since 1973. Providing you fuse for 15 amps it should outlive you,me and the rest of the World. It's about $20 CDN. I used to make them3-4 decades ago...

Now that 'control unit' appears to turn the 'charge light' on/off . It could be a simple relay inside though I don't know for sure.Should be possible to rewire to be like the 'idiot' light cars had in the 60-70s. It's NOT required to charge the battery according to the wiring diagram.

Unless you use OEM parts,you'll have to cut/connect a few wires.
I have to think someone here has already done this,maybe post the parts and proceedure
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