AJS & Matchless Owners Club

Help needed with electrickery.
Whilst the G12 stood for a few weeks the ameter started sghowing a + whilst stationary. So I decided to investigate. The light switch was showing signs of having been apart once or twice before ( might have been me) so decided to change it for a more modern one I've never used. The dynamo is charging ok, but I don't seem to be able to show any charge or discharge at the ameter. My problem is I'm not sure where the wires from the solid state regulator connect on the ameter and the light switch. The workshop diagram shows wire from A terminal connected to the light switch, but as the new switch is different from the old one where exactly should it connect to. ei. does it connect to the same terminal as that for lights. And, whats the simple way of testing the ameter just to show some movement, at the moment the needle does not show a + or -.
The old switch had dodgy soldered on wiring to numberless terminals the new switch has screw terminals that are numbered.
Your patience with this ramble is much appreciated.

Hi

Without knowing which switch you have this is a little difficult to explain:

The light switch will have a terminal for power 'IN' that is connected to the wiper - this is the terminal that needs to be connected to the rectifier and also the ammeter. The other side of the ammeter should be connected to the battery negative.

The various light combinations will come off of the other used terminals.

To test the ammeter, connect one side to the battery negative, run a wire from the other side through a headlamp bulb and on to the battery positive - you should see a negative indication on the ammeter, if you see a positive one reverse the connections to the ammeter. Mark the ammeter terminals to indicate which is +ve and -ve

If none of the above makes sense post a photo of your new switch.

Regards Mick

Hi, I'm sure you've probably done this, but have you tried the ammeter in isolation to make sure it's working? I had one pack up on a Model 18 once, and wasted some fair time checking everything else.

Malc

Thanks Mick, thats very clear. I wasn't aware of the wiper terminal ( a little knowledge, as they say) and I've discovered that the ammeter is us, so another on. order.
And Malcolm, why didn't you mention the ammeter before
thanks all

1608 wrote: I wasn't aware of the wiper terminal

Hi John

The 'wiper' is an over simplification of what you probably have but the theory is good - if you post a photo of your switch, (from above and below), I may be able to identify the internal connections and terminals.

Regards Mick

Hi Mick, I assume you are familiar with these sort of switches, but I'll just clarify that the first and last terminals are not numbered.I believe terminal 4 is the in terminal. It does not show in the pic but there is a strip of copper btn 4 and the switch centre and the sprung ball bearing is the 'wiper'. Can you explain brifly how this switch should be connected and whats the function of the sprung toggle that connects to the first and last terminal. As it is all the lights work!

Apologies for a hijack, but it is relevant while you're on with the job

While you are on with this, any suggestions how to make them less of a pain? I've always struggled with making a good connection and avoiding the loss of copper due to chafing where the wire goes into the "posts" through the slot, like at post 4 in your pic.

Johnny B

John, my efforts may not look too neat but those wires have been in and out of the posts a number of times experimenting and getting in a mucking fuddle. I believe I'm winning now though.
However, the job is much easier with the switch removed.

Hi

That's a Lucas 31371, (RS39) type switch, the same as I have on one of my bikes - here's a snag of the internal connections and how I wired it:
U - Blue - Dip Switch
NW - Brown / White - Ammeter, (Power IN)
R - Red - Park Light
GB - Green/Black - Tail Light
NG - Brown/Green - Speedo Light

(Low and High on the switch diagram would have been better identified as park and driving )

The large brass bridge is redundant in your application, (as it was in mine so has been removed).

I agree, the terminals don't lend themselves to multiple rewires and are prone to damage the individual cores - I try to get them correct the first time and don't over tighten. Another approach is to tin the ends before you make the connection which makes them more resilient to damage but increases the potential for damage by vibration - 'you takes your choice'

Regards Mick

Hi Mick and thanks for simplifying what is curiously a confusing job when one hasn't a clue. Just one quick clarification if you will. On your diagram terminal 5 is shown with a dot, distinguishing it from the others, any significance?
regards