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Re: more charging issues. plus a dicky starter

Oh dear
Decades ago there was much concern that an A bomb exploded in the atmosphere would generate an electromagnetic pulse sufficent to wipe out all elctronics. I gather the Russians persisted with valves to counter. Beginning to wonder if some such has demagnetised Seven dynamos!
It may be of interest to measure the volts at dynamo output.
Do any of the club sites have details for mechanical setting of the cutout?

Location: Auckland, NZ

Re: more charging issues. plus a dicky starter

Does the ignition warning light work? I had the same issue with a car where the warning light didn't work which was resolved when the warning light was fixed. Is the starter shaft bent Hedd?

Re: more charging issues. plus a dicky starter

Dave. Yes the warning lamp works.

Starter shaft. Dont know. Ill look when I swap it for the spare

Location: not north wales any more

Re: more charging issues. plus a dicky starter

OK, so start the engine run at fast tickover, do not touch the cut out and check the dynamo output voltage at the dynamo terminal D and it's case. Mind your digits on the fan or better still remove fan belt. If you get no volts, it suggests that there is a poor connection in the dynamo field circuit (basically any of the connections in the little house on top of the dynamo) which is stopping the dynamo self exciting). By closing the cut out you are putting the full battery voltage on the field which overcomes any dodgy connection. The field fuse clips can be troublesome.

Re: more charging issues. plus a dicky starter

Regarding the starter motor , I would suspect either worn brushes or weak brush springs , do not be tempted to undercut the commutator ; or a dirty Bendix drive . With the Bendix drive , just wash off all the crud at that end of the shaft with paraffin but do not oil it afterwards .

Merv

Re: more charging issues. plus a dicky starter

Dave Mann
OK, so start the engine run at fast tickover, do not touch the cut out and check the dynamo output voltage at the dynamo terminal D and it's case. Mind your digits on the fan or better still remove fan belt. If you get no volts, it suggests that there is a poor connection in the dynamo field circuit (basically any of the connections in the little house on top of the dynamo) which is stopping the dynamo self exciting). By closing the cut out you are putting the full battery voltage on the field which overcomes any dodgy connection. The field fuse clips can be troublesome.


Thanks Dave. My dynamo I believe is a later item. No little house, just two connections. I shall investigate. Might have to buy a multimeter first.

Location: not north wales any more

Re: more charging issues. plus a dicky starter

I can't help with the charging and I believe that Dave Mann is the best person for that but the one about the starter is interesting because mine does the same.
I'm assuming that that is on an earlier A7? Mine is a 1931 RN with the rearward facing starter and it feels/sounds like the engine is too hard to turn over but only sometimes. I have newish brushes and I wondered if the problem is a dodgy earth so I'm going to try a direct earth from the starter motor casing to to the battery.
Brian

Location: Near M1 Jtn 28

Re: more charging issues. plus a dicky starter

Brian.

Sorry. Theres a typo in the original post. Its a 1930 saloon. Short wheelbase steel body. Without getting too technical a stumpy version of yours.

I must admit. The starter was in the boxes of bits that came with dads 1930 chummy and was fitted without even an inspection. And has worked trouble free since (20years).

My engine is direcly earthed with a strap to one of the gearbox lid studs. So I rather hope Ive a good earth. Perhaps I should take the ali casting off over the flywheel and give all surfaces a clean?.

Inside the coppery strips (commutator?) Does seem worn, and they seem to nearly touch. Yet the brushes have lots of life in them as did the springs. There was a little wear to be felt in the back bush.

Location: not north wales any more

Re: more charging issues. plus a dicky starter

Re. Charging problems.
The symptoms you describe would indicate that the cut-out control winding is not doing it's job. This could be due to the winding being open circuit or there is a broken or faulty connection. First, check that the E (earth) terminal is properly earthed.
Using a digital meter (Yes these are ideal for measuring low resistance, but little else!) Measure the resistance from the E terminal to earth/ body /chassis /engine. Ideally this should read 0 ohms, but in practice this is seldom achieved and a couple of ohms is acceptable. More than 5 ohms needs to be investigated. If this is OK, remove all wires from the cut-out and measure the resistance between the D and E terminals. For a 6 volt cut out this is usually between 35 and 40 ohms.(double for a 12 volt version)
If this reading is infinity or high (say 100 ohms or more) the cut out can be assumed to be faulty. Further investigation of the cut-out might enable it to be repaired.
If the above doesn't identify the problem, there are a few other checks that can be made.
Good luck,
Vince

Location: MOONRAKER COUNTRY

Re: more charging issues. plus a dicky starter

You really need an analogue meter for measuring charging rates, such as an avo 7 or 8. A radio ham pal of mine has just bought one for me £12, which includes 2 brand new leads.

Roly

Location: Upton upon Severn

Re: more charging issues. plus a dicky starter

Sorry to be contrary but the car ammeter is sufficient to check currents. The scale can be vaguely checked from the head and tail lamp consumption; total watts divided by 6.
Other amp meters, including the ammeter function of multimeters, tend to be expensive, very easily wrecked by accidental excess current, and may introduce a confusing resistance.
The question here is not so much current but whether or not the dynamo is regularly initiating voltage generation, and whether or not the cutout is receiving/responding.

Location: Auckland, NZ

Re: more charging issues. plus a dicky starter

A 6 volt bulb connected to the D terminal and the dynamo case will tell you if the dynamo is doing it's stuff, if it is don't rev it too much or you'll pop the bulb.

Re: more charging issues. plus a dicky starter

Aha Dave. Thats my sort of electrics. Is 'D' marked?

Some background is that approx 12 months ago the cut out stuck shut. Left all day the battery was as dead as a dodo. And the dynamo rather warm. Forcing the cut out open and with a top up I got home.

I changed the cut out to one supplied by father. Seemingly 'overhauled'. All worked fine. However it has clearly had the coil rewound and the soldering looks distinctly amateur.

I do have the proper dynamo for the car, I believe one of Vinces. Trouble is when the engine lunched its timing gears it didnt do the dynamo gear the right lot of good. I shall have to hunt out an early dynamo gear perhaps.

Location: not north wales any more

Re: more charging issues. plus a dicky starter

Unfortunately I'm not too familiar with the DEL dynamo, however if you try in the winter charge position you can try on either terminal.

Re: more charging issues. plus a dicky starter

Er, at the risk of protracting this forever, any test bulb should be reasonably low wattage.
The shunt generator has the curious feature that with the output isoalted from the battery and short circuited to earth, no significant current flows. Normally, before the cutout closes, the dynamo is supplying only the field and the 30 ohm of the cutout. A large watt bulb cold approaches a short circuit, and the dynamo will find it more difficult to get going.

Location: Auckland, NZ