1997 CB400 Four charging issue 🤯

[Gaz_hay]

Sorry about the delay, finally had time to dig the old girl out and do more checks - thanks to your lot I’m finally getting somewhere can’t thank you enough

I’ve tested the black wire with ignition on and I have 12v …. When. It’s connected to the regulator/ rectifier there is no 12v coming out of the white wire to the field coil (my understanding this should have the 12v the black supplies )

Forgot to mention mine had the new style regulator / rectifier all in one not the one you can adjust …
 Have attached picture (to show what it looks like offline ) 😇

[exvalvesetdabbler]

It may be toast.  If it's getting power and not giving any out to the field coil.

If it were me I would try to find a used original.  As Bryanj says they're pretty robust mechanical devices.  Usual problems are oxidised contacts if they haven't been used for a long time. There is a rubber seal around the cover so moisture shouldn't have an easy way in. Downside for you if you go that route will be needing a separate rectifier as well.

I have a mistrust of no-name electronic devices from the far east but everyone is different.

Regards
Dave

[K2-K6]

Perhaps one from a later Honda

https://www.ebay.co.uk/itm/277950477570 combined unit from OEM supply, would need individual "adopted" loom end into existing SOHC plug.

[Oddjob]

Electrex do a combined reg/rec for the cb400. Seem to recall it uses Mosfets as well, which is usually a sign of a decent one. Connectors seem to be plug and play as well.

[Bryanj]

Thats not a "later" one its an aftermarket one, they can be very unreliable and it only take a fraction of a second of reversed polarity to wreck them

[K2-K6]

Thats not a "later" one its an aftermarket one, they can be very unreliable and it only take a fraction of a second of reversed polarity to wreck them

It's not from SOHC F2 but later twin cam 750 (not the 70s replacement for SOHC motor either) that was original fit "OEM" and Japanese supplied component.