solid state rectifier regulator SH 548

All the smoke escaped from my wiring, and melted the fuse holder. I have a MK3 850 with a solid state regulator rectifier, and after rescuing the bike today after a little electrickery yesterday, I bodged it up enough to get home. Looking at the sorry state of the wiring generally, I thought I would tidy it up.
apart from the ac inputs from alternator, there are 3 leads, Red, black and brown. Instructions assume - earth, but works the other way.
Red goes to + battery
Black goes to - battery
Brown to ignition lights etc
My question is, where should the fuse go?
I now have it between Black and - terminal on battery. which I think will isolate battery if there is a short.
The brown is going to the ignition switch, and red to + battery.
Now bike no go! dead as the proverbial doornail. It is showing 12.5V between _ and frame, and switch and frame. when turn ignition on drops to .3 volts or there abouts.
should the brown also be connected to battery?: Thats how I had it before with the fuse in that lead, not the black.
I have no warning light assimilator... Sorry for the rambling but its witchcraft as far as I can make out, and any help, wiring diagram etc most gratefully received!
Cheers

More characters.

Looks to me like you are poking around without the benefit of a wiring diagram. That would be a good place to source your information.

Johnny said:

All the smoke escaped from my wiring, and melted the fuse holder. I have a MK3 850 with a solid state regulator rectifier, and after rescuing the bike today after a little electrickery yesterday, I bodged it up enough to get home.

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How (or when) did this happen? Were you just riding along or what exactly?

What type of fuse?

If it was a 'glass' fuse, what type? Was it a continuous or blow rated fuse as not all fuses are same even though they may be marked with the same amp rating as you need to find out why the fuse did not blow before the fuse holder melted and the wiring started to burn.

Johnny said:

apart from the ac inputs from alternator, there are 3 leads, Red, black and brown. Instructions assume - earth, but works the other way.
Red goes to + battery
Black goes to - battery

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Correct (assuming black is the negative wire).

Johnny said:

Brown to ignition lights etc

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From what I can find out about the SH548, the fifth wire is likely to be a voltage sensor wire which is connected to the 'switched' section of the main electrical power feed, once again, this is assuming that black is negative and also that the sensor wire will operate when connected to the negative side as that type of regulator is normally intended for use with negative earth systems so it would normally connect to a 'positive' power feed.

Johnny said:

My question is, where should the fuse go?
I now have it between Black and - terminal on battery. which I think will isolate battery if there is a short.
The brown is going to the ignition switch, and red to + battery.

Click to expand...

That would be the normal position for the main fuse (see Mk3 wiring diagram, link, below) however, you can connect the regulator negative directly to the battery(-) but preferably using a separate fuse.

http://britmoto.com/manuals/Manuals/850_man.pdf
Wiring diagram Section J, pdf p.163.

Johnny said:

Now bike no go! dead as the proverbial doornail. It is showing 12.5V between _ and frame, and switch and frame. when turn ignition on drops to .3 volts or there abouts.

Click to expand...

What about with the regulator disconnected?

Johnny said:

should the brown also be connected to battery?: Thats how I had it before with the fuse in that lead, not the black.

Click to expand...

One out of the two will be the negative and the other I think, is a system voltage sensor, so it's possible that brown could be the negative.

Thanks everyone, I have the proper workshop manual with wiring diagram, but this is a non standard part that does away with zeners, rectifier etc.
I put in a fused lead from - to the brown green power circuit to ignition switch and voila! all seems good. Cant start it to ride it now as the neighbours may take umbrage, but will test on the morrow.
Thanks again