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Main fuse blowing, is it a voltage regultor?
https://www.trf.org.uk/forum/viewtopic.php?f=36&t=23838
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Author:  Mitso [ Mon Jul 24, 2017 9:55 am ]
Post subject:  Re: Main fuse blowing, is it a voltage regultor?

Having slept on it and given it some thought, you are correct as I was measuring a live wire, so when the fuse it out and it's not live then there is no negative reading to earth and in fact no reading which also indicates no short so I can discount the red wires as well.

Back to waiting for the rectifier.

Author:  Bill_Mc [ Mon Jul 24, 2017 11:37 am ]
Post subject:  Re: Main fuse blowing, is it a voltage regultor?

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Author:  Mitso [ Fri Jul 28, 2017 7:19 pm ]
Post subject:  Re: Main fuse blowing, is it a voltage regultor?

Have fitted new regulator and the fuse doesn't blow, still not sure if its charging properly(V doesn't seem to rise as much as before) but will take it out over the weekend and report back, but as long as the fuse is not blowing looks like heading in the right direction :)

Author:  Bill_Mc [ Sat Jul 29, 2017 12:54 am ]
Post subject:  Re: Main fuse blowing, is it a voltage regultor?

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Author:  Mitso [ Mon Jul 31, 2017 8:21 pm ]
Post subject:  Re: Main fuse blowing, is it a voltage regultor?

CRF230F, out riding the other day and it kept blowing the main fuse by the battery. I could see from my Trail Tech instrument panel that the voltage was fluctuating widely, from about 8v-20v. I guess that's what was blowing the fuse.
I don't think its the battery as when I replaced the fuse it started ok. I could bump start it when I had run out of fuses and voltage with a blown fuse was between 0v-3v.

Put a 15amp fuse in, the Trail Tech registers 12.5v, turned on the ignition and the fuse pops (no lights on or starter button pushed). Had a quick look at wiring and nothing obvious so now taking the tank off and investigate further on the wiring. I have changed the battery and no difference so that's discounted.
Bought a new regulator and seems to work ok with no blown fuse and everything working normally (lights, starter etc), try it on a ride soon.

UPDATE - Riding today, started off for first 10mins absolutely fine with the new regulator, charging at about 14.5v, very happy. Then the same thing happened, I noticed the V fluctuating wildly and the fuse had blown again. So back to square 1.
WITH THE FUSE DISCONNECTED - V with engine stopped - 0V..... engine running on idle - about 15v,.... engine revving a bit - about 20V.
Could the new regulator have blown/ faulty or is there some short blowing it.
Is there a way to check the regulator?

Author:  smokinrider [ Mon Jul 31, 2017 9:14 pm ]
Post subject:  Re: Main fuse blowing, is it a voltage regultor?

That's the problem with replacing items before you have diagnosed the fault.

Back to basics. Check all wires and connectors are sound clean and not corroded and all wires are kink and break free.

Separate connectors at both ends of a wire and test its resistance. There shouldn't really be any of its all sound.

Then test the rectifier.

Then check the windings but as you have a voltage rise when running it's unlikely to be that.


TBH it sounds like a bad earth somewhere. Or a broken wire, bare wire.


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Author:  mancchair [ Mon Jul 31, 2017 10:20 pm ]
Post subject:  Re: Main fuse blowing, is it a voltage regultor?

After doing the above I think you then need to check your generator coils, I believe the resistance readings should be about 240 ohms across blue/yellow to green. exciter coil is black/red to ground about 190 ohms,
I would also have a look inside the generator cover for any debris floating about which could be causing voltage spikes, I have had this happen on two occasions admittedly not on a Honda but it's worth checking :)

Author:  Mitso [ Mon Jul 31, 2017 11:30 pm ]
Post subject:  Re: Main fuse blowing, is it a voltage regultor?

Am I right in saying that the circuits I need to check are to regulator/ignition sw/ starter button, then alternator coils.

How do I check the regulator/rectifier?

How come everything works (apart from no charging) when I unplug the regulator - starter/stop, lights n horn. Does that narrow it down to alternator or regulator?

Author:  mancchair [ Tue Aug 01, 2017 7:25 am ]
Post subject:  Re: Main fuse blowing, is it a voltage regultor?

It doesn't narrow it down as the ignition coil and power coils are separate in the alternator, if the new regulator is faulty chances are something has caused this and the prime suspect for me is the generator, the regulator may not be faulty but may have an unsteady input from the generator :|

Author:  smokinrider [ Wed Aug 02, 2017 2:55 am ]
Post subject:  Main fuse blowing, is it a voltage regultor?

I'd imagine bulbs would blow before the fuse if it was anything else other than a short.


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