Blown fuses

[Lobo]

Oggers, within the Regulator the Black is connected to Green- via a winding (in red on the attached diagram). My point is, depending on how you are using your multimeter, you might be wrongly assuming a false earth on the Black. Don’t use the beeper between Black and Green (my two blue marks), but rather the Ohm scale. Compare what you see with directly putting the two probes together... which would signify a true earth fault.
Sorry... but can’t tell you an expected Ohm reading between the Black and Green terminals, but it won’t be 0 (pure short) and it won’t be infinity (open circuit).
It’ll be great indeed if the Black on the regulator is definitely shorting to ground....
Simon

PS Have you tried a 15A fuse back in the circuit with the Regulator disconnected to confirm if it’s the culprit... this might be the easiest way.

[Bryanj]

Ooops, forgot that. Is there not a sub loom on the 400 Julie, its been a lot of years since i did electrics on one of those. All basically same just slight variations

[Lobo]

Oggers... just put an Ohm meter across the Black & Green of my 400F Rectifier (and disconnected from the loom).... saw 108 ohms.

[Bryanj]

Quick look at parts list tells me no sub loom so if the black goes to ground only when connected to regulator has to be regulator fault, if goes to ground when not connected loom has a problem or wire trapped/connected wrongly somewhere

[Oggers]

Chaps

To confirm various things

Two multimeter probes crossed gives a reading of 0 Ohms

Test 1

Red probe to the single common BLACK wire at the headstock multi-connector. Everything else on this common disconnected except to the regulator
Black probe to earth/ground

Result - Resistance of 0 Ohms - Short?

Test 2
As above, but with regulator black wire disconnected

Result - Infinite Ohms - No short?

Test 3

Red probe on green regulator terminal
Black probe on black regulator terminal
All wires disconnected

Result - 0 ohms - short inside regulator?

Overall result - duff regualtor?
 

[Lobo]

...I’d reckon job done; and indeed it seems the Regulator has gone bad describing the 3 checks you did.

The last bit of your puzzle will be confirmation with a 15A fuse in place... but Regulator disconnected of course.

Seems an odd sort of failure... has the Regulator Black contact somehow bent / contacted the body?

Regardless, hopefully well done.

Simon

[Bryanj]

The proper 400 reg has contacts that poinr sideways whilst the other fours point downwards perhaps the wrong one fitted

[Oggers]

Simon/Bryan

Firstly many thanks to you both. Would not have found it without you.

Yes - for sure I will reconnect everything except the regulator, insert fuse, turn the key and see what happens. It had better not blow!

I'll pull the regulator off to see if I can find anything obvious, but yes, a little odd for sure. I never touched it! Some elderly capacitors in there, so I guess they have a shelf life.....

Pins point outwards by the by

May invest in the reg/rec combo as a fix....

[Bryanj]

No capacitors, all coils n points.

[Bryanj]

Have you stopped the blowing fuses?

[Oggers]

Bryan - not quite 100% rewired just yet - further problems!, but so far, 15A fuse back in, disconnected from regulator and no blown fuse. 

[mike the bike]

Glad you've traced the fault.  With so many things connected to the positive,  it can take a while to eliminate the fault.  Time is something we have oodles of at the mo.
Is you reg the original metal can one or is it a more up to date reg/rec ?

[Oggers]

Mike

Its the old seperate type. Lord knows why it seems to have just stopped functioning. Took it apart, cannot see anything obviously amiss. Ordered up replacement.

[oapcb400]

a year or so ago on a german website i came across a person/company? who were advertising a modern rec/reg unit that was housed in the original "can" type unit.  has any other member come across this item?

[mike the bike]

Most people go for the combined reg/rec.  You'll need to alter the wiring slightly, and you could leave the faulty one in place.