I´m attempting to replace the regulator/rectifier on my NC30 with a new Honda reg/rec SH693 (with big heatsink & fan). A previous owner has cut off the loom´s reg/rec connector. It shouldn´t be a problem. But, with the three yellow wires connected, and the earth wire, when I connect red/live sparks fly, the circuit shorts out, and the main fuse blows.

I have wired in a separate earth, direct to the battery, which connects to the reg/rec. The question is, why should the live wire short out when it is connected to the reg/rec?

I also tried wiring in a wire to the battery positive to substitute the live wire. On connection, the result was the same - sparks, short, blown fuse (one I´d mounted next to the battery connection).

What´s non-standard? I have replaced the right-hand side connector block (the one with three yellow wires) with soldered connections as it was previously a point of failure (the connector block got dirty and burned out). The connectors in the reg/rec are lightly insulated with clear plastic rubber shoes (these I´ll replace with a proper connector block as soon as I can get hold of one).

The alternator tests fine, 0.8 Ohm for all three yellow wires. The earth is direct to the battery. Therefore the ¨live¨ connection is the problem. I can´t for the life of me figure it out, despite checking against the Haynes manual wiring diagram.

The only thing I can think of right now is that the negative terminal of the reg/rec should be connected to the frame not the battery. Does that make a difference?

Any ideas or suggestions? I´ve spent all day on this and still no solution. It´s probably something really simple that I´ve over-looked or not realised. I´d really appreciate some help!

lol don't put the negative of the reg/rec to the battery, you'll blow it up.

Scratch that, edit you mean battery negative right. If so then that shouldn't matter.

-ve is earth
+ve is battey.

Your reg rec.

Original 3 yellow wires from genny, can go in any order.

Red is it? This is battery positive.

Green.. this goes to earth.

If it's shorting out theres a chance the new reg/rec is knackered and has an internal short or you have the wires on the wrong pins.

Most commonly people mix the green and red wires up.

The 3 yellow ones go at the bottom, you havn't mixed the gren and red up have you.. if you wire them backwards it'll pop a fuse

Neosophist wrote:lol don't put the negative of the reg/rec to the battery, you'll blow it up.

Scratch that, edit you mean battery negative right. If so then that shouldn't matter.

Yes, battery negative to the earth on the reg/rec.

Neosophist wrote: If it's shorting out there´s a chance the new reg/rec is knackered and has an internal short or you have the wires on the wrong pins.

That´s useful. I used this guide to wire the pins:

http://www.ebay.co.uk/itm/CBR600-CBR-90 ... 35bb156c29

It´s quite possible that the pin-out shown is incorrect, and that green should be on the right and red on the left pin.

The sun´s just gone down, but let me head and try reversing the pins. I got a few spare fuses in town today. Back shortly...

Neo, you were spot on once again. Once the pin-outs were reversed from those shown in the diagram, everything works as it should. 14.8v across the battery at tickover, a bit less with the headlight on, etc..

I have one question regarding the connector. It seems that finding new reg/rec connectors is darn difficult - I´ve tried loads of different places today. Given the propensity of the three yellow wires to arc-weld themselves together on the RHD connector, would I be right to suppose the connectors in the reg/rec will do the same thing? Or do you think that the clear ¨rubber¨ boots and shrink-wrap ought to be sufficient? The reg/rec shouldn´t be exposed to dirt since it´s mounted under the fairing, bolted to the frame. What do you think?

tanto wrote:Neo, you were spot on once again. Once the pin-outs were reversed from those shown in the diagram, everything works as it should. 14.8v across the battery at tickover, a bit less with the headlight on, etc..

I have one question regarding the connector. It seems that finding new reg/rec connectors is darn difficult - I´ve tried loads of different places today. Given the propensity of the three yellow wires to arc-weld themselves together on the RHD connector, would I be right to suppose the connectors in the reg/rec will do the same thing? Or do you think that the clear ¨rubber¨ boots and shrink-wrap ought to be sufficient? The reg/rec shouldn´t be exposed to dirt since it´s mounted under the fairing, bolted to the frame. What do you think?

The reg/rec one doesn't usually fail as the other one fails first, i've never seen one fail.

It corrodes and oxidises up which makes the resistance higher so it generates heat and burns up.

As long as you solder the connections on and make sure they don't touch you shouldn't have much of a problem