AJS & Matchless Owners Club

My 1958 Matchless G3ls alternator coil ignition model, has a voltage drop.
I,ve left the multimeter connected to positive and earth on the battery terminals overnight with everything connected except the coil lead to points and the 3 leads to the rectifier and it's 5.8v didn't drop.
This morning I connected the coil lead to the points but not the rectifier cables and the volts slowly started to drop, it immediately dropped to 5.3v but then continued to slowly drop to so I disconnected and battery voltage stopped dropping.
I have a new solid state rectifier on route as originally I thought that was causing the voltage drop.
Any ideas what to do next, new condensor, or points maybe.
I must be getting close to the cause.

It's a long time since I had the 1966 14 CSR but it will have had a similar system. I had no problems in this direction but looks to me like you are following a careful route of elimination and only changing one thing at a time. That's sure to bring dividends.

Only thing I have found is that it can be useful to make a note of what you've done (your post probably fits that) as it's easy to get a bit flustered when things get complicated. Then you forget what you've done and what you haven't done.

Johnny B

Hi

Your ignition switch does not seem to be isolating the points, (I assume you are seeing the current leak with the switch selected 'OFF'), I'd start looking there.

Regards Mick

Thanks Mick,
I have the ignition switch on, I will connect coil to points lead again when I get home and with the switch OFF will hopefully still get the drop, at least I will know the switch is causing the problem.
Getting close me thinks,
Thanks again.

Hi

If the ignition switch is 'ON' the coil is supplied and circuit completed by the closed points, (statistically the points will be closed most times), this is the correct mode of operation. If the points are open the battery will not drain.

Switching the ignition to 'OFF' should remove the supply to the coil and stop the battery draining.

Regards Mick

Thanks Mick,
Pretty sure it sounds as though the switch is causing the problem, i remember separating the points after the battery started to drop, and the voltage continued to drain.
I will double check and get one ordered,
Any chance you could advise part number from Jampot no pics so confusing for me.
Thanks for your help.

Hi

For a 57 single it should be 351551 according to the list but before you commit I'd verify the switch is the culprit - I think you'll find the white wire supplies the coil, if you remove it from the coil and then put the meter between the wire and coil it will indicate if there's a flow with the switch on and off.

Regards Mick

Ther was no voltage drop when you disconnected the lead between breaker point and ignition coil. There was when you reconnected that wire. Hence the fault will not be in the switch.

Albert

aobp11 wrote:Ther was no voltage drop when you disconnected the lead between breaker point and ignition coil. There was when you reconnected that wire. Hence the fault will not be in the switch.

Sorry - but if the switch is faulty and supplying the coil in both on and off states disconnecting the CB from the coil will give exactly the symptoms seen, (assuming the points are closed).

Regards Mick

Just to update ignition switch turned OFF no voltage drop I have put everything back together and now with fully charged battery I have no spark at plug, will have another go in morning.
Coil lead to ignition sparks whilst removing coil lead, but when fitted and points closed/opened no spark at plug.
Thanks for help though.