Dynamo wiring help

[Chris Spencer]

I'm trying help a Kestrel owner (car was his late fathers and has recently been left to him) - its an all original car in a good oily rag condition & has been with the family for the last 55 years - he needs help with the dynamo wiring has in what order it should be wired - images below - can anyone please advise

20190922_143410.jpg

20190922_143434.jpg

Or possibly Mr Clements you could help - its down the road from you in Chalfont St Peter - I can put you touch with the owner and possibly we can gain a new member with the brownie points ?

Many thanks - Chris

[BarryCambs]

I was faced with something very similar with mine, but I felt a whole lot better once I'd ripped the wiring loom out and binned it! I think the first thing to do would be to satisfy yourself the cut out is working before going any further. It could be its failure is what's prompted someone to try and modify the wiring? I fitted a solid state cut out to mine, as it was going to be very expensive to have the original rewound. I think it was only about 20 quid from Paul at Smart Power and works well. In truth, if I was rebuilding another dynamo, I'd probably convert it to 2 brush set up and go with a proper solid state regulator like a DVR3, as it does tend to undercharge on short journeys and over charge on longer.

cut out.JPG

I'd check the field coils for continuity, as they can burn out if a feed straight from the battery has been put across them for any length of time. If all is well, from memory, 3 wires should be coming out through the rubber grommet under the cut out. A thicker wire from the live brush goes to one side of the cut out. A smaller wire (also connected to the main brush) connects to the field coils shunt resistor contained in the cutout and the wire to the field coils connects to the other side of this. I can't remember how this worked on the original cutout, though I have a spare at home I can look at.

The summer/winter switch on the dash basically bypasses the field shunt resistor in the winter setting . Looking at the control box terminals, from the left is the connection to the charge warning light. Middle terminal is the wire from the 'winter' switch setting which effectively shorts across the terminals to bypass the shunt resistor. The right hand terminal is the positive feed to the amp meter (via a fuse). Once screwed back on to the dynamo, there shouldn't be any need fora separate earth on the cut out, as is fitted in the picture.

There is a very clear scan of the later wiring diagram in the technical library:

viewtopic.php?f=95&t=4594

Barry

[Tony Fearn]

Hi Chris and Barry.
Here's a scan of the 1935 wiring diagram.
Tony.

1935 Wiring diagram.jpg