Lights, capacitors, action.

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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The Vandal
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Re: Lights, capacitors, action.

Post by The Vandal »

clive wrote: Thu Oct 27, 2022 1:44 pm If the ammeter does not go to discharge when the headlight goes on its probably faulty.
My ammeter needle has never moved in response to moving the headlamp switch as far as I can remember.

It seems to move mostly randomly, I don't think its ever done something one day and then done the same thing in response to the same input the next day!

New one is on it's way.
Groily
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Re: Lights, capacitors, action.

Post by Groily »

When the new one comes and you have the old one in your hand, it might be an idea to do a simple check with a battery and a bulb to see if it does actually work.
If you connect a bulb to the battery, with the old ammeter in-line with one wire to the bulb, you should see the needle move one way or the other when the bulb is lit. If it does, it shows the ammeter is capable of registering activity.

I suggest this because if you then fit the new one and find that there is still no movement when you switch things on, it says there is an error in the basic wiring (and you may have got yourself a spare good ammeter).

One terminal of the ammeter should carry the lead to/from the battery live terminal - that'll be the negative one in your case.
On the other terminal should be the wire 'A' from the voltage regulator, and the wire that goes to the light switch - to position 3 if it's the standard Lucas 'OFF L H' type.

If, for example, the wire to the switch has been taken from the same side as the lead to the battery, then the needle won't budge when things are switched on because the current isn't going across the ammeter. (This is quite a common mistake.)

If the wiring is 'correct' but the needle moves the 'wrong' way, swap the wires over on the ammeter to reverse that.

I remain of the optimistic view, from what you have said about battery voltage at revs and so on, that you have a dynamo that works and a regulator that regulates within the prescribed 7v-7.5v range. Your battery may be too small, and/or typical machine usage and engine speeds may be inadequate to keep it charged, coupled with this inability to see what's happening on the ammeter, but I'll be surprised if, when you have a reliable ammeter correctly wired, you don't see readings that make some kind of sense!
The Vandal
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Re: Lights, capacitors, action.

Post by The Vandal »

It’s taken me a while to get round to working on the bike again.

I swapped the wiring round so that the regulator goes straight to the meter then over to the headlight switch.

That seemed to improve things a little, lights seemed to be staying (dimly) lit at low revs and then subbing in the new anmeter made things even better, the needle now snaps from the middle down to -4 with the sidelights on and -8 with the full lights on…

…BUT…

…no charging.

I’ve noticed there’s what looks like a place to plug in an Earth wire on the lighting switch (there’s a similar looking bit on the headlight bulb holder and it goes to earth) but on t the switch there’s nothing in it so I’m off to fabricobble something to go in there just now.
The Vandal
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Re: Lights, capacitors, action.

Post by The Vandal »

Image

What I thought was the earth connection cicrcled in red. Connecting it to earth didn't seem to do much.

I checked the charging again and there was some but inconsistent. No lights on I'm getting 3-4v at tickover and 7v with higher revs. Once I put the lights on the charge drops obviously but with the light switch at 'L' I still get a couple volts at tickover and a bit more with revs, switching to 'H' at tickover just straight kills the charge and revving doesn't bring it back, I have to turn the switch back to 'off' to get it charging again.

The wiring within the headlamp nacelle seems pretty different to any of the wiring diagrams and a lot of the connections are pretty shonky so I've started trying to rectify that but I'm getting a bit stumped with the light switch.

The copy of the wiring diagram I have...

Image

...shows a lighting switch with way more connections than mine has and is too low resolution to read very clearly.

Anyone able to tell me how the connections should go on a Lucas U39 switch or link me to a diagram?

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Groily
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Re: Lights, capacitors, action.

Post by Groily »

In a nutshell, with these ones with the rocker arrangement -

Power in from ammeter to 3 (as always), dipswitch from 2, pilot light 4 and tail light and speedo light 5. Ignore the rockers.

No need to have the headlight main / dip coming off the switch as in your diagram - just power the dipswitch from 2 and then run leads from dipper direct to bulb - same thing, and simpler. Think you probably have that already - see attached diagram.
For the switch numbering, see pix here. Basically, the sequence goes in a clockwise circle from the rear.
https://www.matchlessclueless.com/store ... ng-switch/

Can't quite see how you have things - but a basic working arrangement with this type of switch is the same as for the one without the rocker thing or 'swipe' to the cam. (Bakelite cam switches have the 'swipe' link internally set up.) There are 7 terminals, same number but not all the same to look at, as in the diagram you posted. Don't need them all. You need 2 3 4 & 5.
With regulator A wire & link to switch 3 on same side of ammeter; other side of ammeter to battery (and maybe brake light or whatever).
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The Vandal
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Re: Lights, capacitors, action.

Post by The Vandal »

That diagram is very similar to one that was posted on the facebook group when I asked last night,

Image

I've wired up as per these diagrams and it all works - well, mostly. I haven't connected the speedo light yet and I've done something wrong with the horn so it doesn't work but the important stuff does!

I had 3v in the battery this morning, went out for a run with no lights for first 1/2 then put them on (and inadvertently was on full beam) for the way home home. Headlight stays on when stopped at lights/junctions, ammeter behaves as you'd expect (only quirk I noticed was that upon applying the rear brake and the brake light coming on, ammeter needle shows an increase in charge over brake light off?) and there was 6v in the battery after the ride!

A great success!
Groily
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Re: Lights, capacitors, action.

Post by Groily »

The diagrams are darn near the same, so not surprised! There are basically 'dynamo diagrams' and there are 'alternator diagrams' (in loads of versions of increasing complexity owing to gradual progress with regulation and the extra leccy bits that came along) but the dynamo basics never really changed once the format of '2 brush dynamo and voltage regulator' was adopted before most of us were born.
You can happily use any of the drawings really - I only put that one up yesterday because you said you couldn't easily read the one you'd posted. Variables are only really 'which earth', 'what voltage' and some options on details of the wiring (like the dipswitch thing, whether the brake light & horn come off the ammeter or not, etc.)
One thing none of them shows is a FUSE however . . . the diagrams in the other thread I referred to yesterday shows where they might go. I wouldn't be without at least one, and it needs to cover everything.

Sounds as if you've got there, which is great.

Ref the 'charge showing with brake light on' bit -
With your brake light wired directly off the battery and not through the ammeter, then when it's lit the drain on the battery will be compensated for by the regulator, which asks the dyn to produce a bit more to offset the load. The battery feels the drain and the charging side reacts to it, but the ammeter doesn't show it - but it DOES register the compensating boost as a positive. That's as it should be - and it's how I know my brake lights actually work without straining my neck further than it goes these days to look!

Fingers crossed it all hangs together for a bit.
The Vandal
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Re: Lights, capacitors, action.

Post by The Vandal »

Aye, I've got a fuse on the -ve battery lead, that lead coming from the ammeter goes into it along with a few other leads that I think are from the tail light.

Cheers for explaining the brake light/ammeter thing!

Need to get a retaining clip for the lighting switch, it was glued/siliconed in place (more of that evidence of someone with 10 thumbs being there before) and I'll do the speedo lamp and call it done. For now.

Looking at the tea bag, sorry, chaincase next.
The Vandal
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Re: Lights, capacitors, action.

Post by The Vandal »

Should the bullet lights and ‘pilot’ bulb within the headlight extinguish when switching to ‘H’ or have I got something in the wrong place? Or maybe it’s a voltage thing?

Getting to the bottom of the horn issue, it was wired completely incorrectly, of course!
Groily
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Re: Lights, capacitors, action.

Post by Groily »

Think they should if their feed is from 4 on switch. If off 5, same as tail and speedo light, then no. 🤞
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