Rectifier or alternator ?

maylar

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I had a problem with my alternator wires recently. I was using 1/4" quick connects on the wires that extended the alternator and one of them was not engaging when the M/F were pushed home. An ohmmeter would have shown zero ohms from one end to the other but the connection wasn't being made when the connectors were plugged in. Don't assume anything.
 

guest76

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You confirmed that your red warning light doesn’t come on, but you never came back about the ‘silver can‘ 3AW assimilator, and whether it is in the bike and wired.

B27E8BA5-EF7A-4FF8-A0AA-15281D139C73.jpeg

If this is still connected, but is faulty, it can stop your reg/rec receiving a decent AC supply.


As stated already, there are a couple of brown/blue wires that may not be connected anymore as tge zener, and possible your ‘blue can’ MC2 capacitor have both been removed.
Note that these are all the battery side of the ignition switch, so are permanently ‘hot’
Make sure they are safely taped up or removed.

FE0D1EE1-E266-4261-9488-AE733AEA3678.jpeg
 

Kjell

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I had a problem with my alternator wires recently. I was using 1/4" quick connects on the wires that extended the alternator and one of them was not engaging when the M/F were pushed home. An ohmmeter would have shown zero ohms from one end to the other but the connection wasn't being made when the connectors were plugged in. Don't assume anything.
Duly noted
 

Kjell

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You confirmed that your red warning light doesn’t come on, but you never came back about the ‘silver can‘ 3AW assimilator, and whether it is in the bike and wired.

View attachment 17996

If this is still connected, but is faulty, it can stop your reg/rec receiving a decent AC supply.


As stated already, there are a couple of brown/blue wires that may not be connected anymore as tge zener, and possible your ‘blue can’ MC2 capacitor have both been removed.
Note that these are all the battery side of the ignition switch, so are permanently ‘hot’
Make sure they are safely taped up or removed.

View attachment 17997
Zener and capacitor has been removed. That I know for sure
 
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I would also suggest disconnecting both of the alternator wires from the rectifier / regulator and checking that they are not short circuited to the chassis / frame of the bike. Expect a very high / infinite resistance from either of those wires to the bikes frame.
 
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I submit that a diode in the rectifier may be suspect. When you use a full wave bridge to rectify AC and when it looses a diode, the ac it sees is noly half the normal ac voltage, no enough to charge a battery. I assume you get 30-50 miles on the fully charged battery before it quits as a fully charged battery should do that. I know you have a replacement r/r but the principles are the same. The variation in voltage you are seeing is suggestive of the rectifier partially failing. I would swap out the recitifer if you have not done so.
 
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The reg has two output wires. I’d test across those wires, first, rather than assume one wire has perfect continuity to the frame.

If you get over 14V at the battery with lights off, but less than about 13.5V with lights on, then the alternator may be low on output.
 
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If the r/r had a bad ground it would also only half wave rectify giving a similar set of symptoms.
 

Kjell

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I would also suggest disconnecting both of the alternator wires from the rectifier / regulator and checking that they are not short circuited to the chassis / frame of the bike. Expect a very high / infinite resistance from either of those wires to the bikes frame.
Thanks for all the knowledgeable input. Time for a cold beer. To be continued tomorrow !!!
 
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I will check in later but need to go now as we have a terrible thunderstorm and I will turn off the computer.
 

Kjell

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You confirmed that your red warning light doesn’t come on, but you never came back about the ‘silver can‘ 3AW assimilator, and whether it is in the bike and wired.

View attachment 17996

If this is still connected, but is faulty, it can stop your reg/rec receiving a decent AC supply.


As stated already, there are a couple of brown/blue wires that may not be connected anymore as tge zener, and possible your ‘blue can’ MC2 capacitor have both been removed.
Note that these are all the battery side of the ignition switch, so are permanently ‘hot’
Make sure they are safely taped up or removed.

View attachment 17997
I will make sure I check in the headlamp if the assimilator is connected. I presume that is where it is located. I can circumvent the whole system by running wires directly from the alternator to the input of the R/R and then directly to the battery. If that doesnt do the trick then it HAS to be low output from the alternator. Does this sound like a plang
 

Kjell

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I will make sure I check in the headlamp if the assimilator is connected. I presume that is where it is located. I can circumvent the whole system by running wires directly from the alternator to the input of the R/R and then directly to the battery. If that doesnt do the trick then it HAS to be low output from the alternator. Does this sound like a plang
plan
 

guest76

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@Kjell you need to make sure that the assimilator is disconnected if you plan to proceed with your new reg/rec

It states in the installation instructions of your new Boyer Bransden Power Box that it is not compatible with the assimilator.


1C4E69F7-FAB3-41ED-A86E-9AAAC1DE6651.jpeg

Disconnecting it should not be a problem though, they are notoriously unreliable and you already stated that you have a charge warning light from ‘improving classic motorcycles’ to go on the bike instead.

If your original assimilator is still attached, you can find it up near the ignition coils.
2F744D64-FFA1-4A23-826A-03CA6882796A.jpeg
 

Kjell

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Updater:
I am giving the alternator and the R/R a clean bill of health.

Connecting my test lamp to the black output wire from the A REG ONE and directly to ground on the battery I am showing a very bright light varying clearly with the RPM of the bike.

I am confident the problem is somewhere in wiring from the point where the connection has been made from the regulator to the brown/blue cabling onwards to the battery. There is no other solution.

Where was the old capacitor located on the original system ? I am seeing some loose cables under the seat with no destination
 

maylar

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Capacitor was mounted to the rear bulkhead in the battery compartment. And as I recall there were 2 brown blue wires to it that needed to be jumpered together if the capacitor was removed.

edit: The old rectifier would have had 2 AC wires that are normally left hanging when removed (taped up of course).
 
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