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Re: DEL Dynamo help

If its the same style cut-out as my RP then there is a "summer charge" resistor in the base. Most likely cause for no summer charge is an open circuit or burnt out resistor.

Rick

Location: Deepest Norfolk

Re: DEL Dynamo help

Richard,
With the DEL dynamo the half charge resistor is contained within the dynamo windings, and it looks as though yours is u/s.
Try connecting a 1.5 ohm high wattage resistor across the dynamo terminals.
An example resistor.
HERE

Bryan

Re: DEL Dynamo help

The definitive article is A Charging Refresher on the Cornwall site. Care is necessary to relate the captions to the relevant diagrams. Explains the efffects of mixed components. And while at it the circuit diagram by John Cornforth on the Dorset site very useful.

10 amps net output is considered about the safe maximum, ideally less.

Note that the DEL dynamo is 4 pole with a quite different armature wind pattern. Such
dynamos can have 4 brushes and if it seems to be oddly placed, the 3rd brush is positioned relative to the missing two!

Bob Culver

Location: Auckland, NZ

Re: DEL Dynamo help

I'm now thinking internal wiring of dynamo is still incorrect. One of the 4 windings has two small rubber covered wires coming out of it as well as the main field wires. At the moment one of these is attached to the field brush but i'm thinking these 2 wires would be the internal resistor?

If that is the case what connects where? As in what does the field brush connect to? Where do those 2 resistor wires connect to?

Am i missing something right under my nose in wiring diagrams?

Location: Moonraking in Wiltshire

Re: DEL Dynamo help

It may be worth checking that the two wires have a few ohms between and insulated to earth as apparently many are open circuit. Assuming it is the resistance wire, one end attaches to the dyn output and one to the field end wire remote from 3rd brush. It is esp important the dyanamo is not operated open circuit or the resistance and maybe more may burn out, if the resitance not already in that common state. Just exactly where the connections are made I dunno, but if the resistance is dud it wont matter! I dunno how the reistance is laid out; if a winding there may be a right and wrong way around.

Bob Culver

Location: Auckland, NZ

Re: DEL Dynamo help

Further to above I notice the Cornwall cct shows the resiatance skipping the first field winding. This seems very odd?! is it an error?

Bob Culver

Location: Auckland, NZ

Re: DEL Dynamo help

I unknowingly fitted a DEL dyn to my RP years ago. Although I had it apart on occasions I did not expect, look for, or notice any resistance winding. With the scuttle mounted fuse removed it did not charge so was open or disconnected. When I did learn of this resistance I chanced to mention to a NZ Seven auto electric authority and he had never heard of! it is a very obscure arrangement made clear in few places other than the Cornwall article.

The skipping of the first field winding as the Cornwall diag is not beyond rational explanation.

Surely there is someone out there who knows and can advise Richard and others on the exact arrangement and how the connections are made. Or has this been done by email to preserve the mystery?

Bob Culver

Location: Auckland, NZ

Re: DEL Dynamo help

According to George Newnes "Motor Engineering" circa 1938.

"APPROXIMATELY SEPTEMBER 1928- AUGUST 1932 :

D E L. Type Dynamo

This machine fitted to the early type coil ignition models differs only in the construction. The armature in this case being fitted with a driving end and commutator end ball-race. The resistance coil is fitted internally, being wound round one of the field coils. This functions in the same way as already described.

The switchboard is of the S.M. type combining the ammeter, ignition and lighting switches. A relay switch assembly is also fitted to ensure the full charging rate when the headlights are on irrespective of the position of the charging switch. The cut-out, although of a heavier pattern, functions in the same manner as the later types. Tests, adjustments, etc., follow the same procedure. The headlamps with double filament bulbs fitted are controlled by a 2 .way switch fitted to the steering column. The starter motor, mounted in this case on top of the flywheel housing by the foot pedals, follows the same line of construction as later models,."

Ian Mc.

Location: Shropshire

Re: DEL Dynamo help

Being not well versed in electricity I carefully study all I can about the Austin Seven charging system.
From very early on (and often mentioned on the forum) the late 1928? up to 1931 Lucas/CAV DEL four pole dynamo (generator) had a resistance wound with the field.
The generally good Cornwall Austin Seven Club 'Charging Refresher' explains this on the first page.
Unfortunately the diagrams and explanations which follow on the DFL and DEL dynamos have some errors (I have advised the author who didn't acknowledge my corrections)
The DFL dynamo was fitted together with the Lucas SM3 switchboard which did not have a half charge setting as suggested, with a shunt resistance behind the switchboard- the switch just connects or disconnects the field winding from the circuit. The dynamo has two external terminals - 'D' connected to the charging brush (the other charging brush is earthed) The moveable third brush is connected to the field winding, with the other end of the field winding exiting through the 'F' for field terminal.
The appropriate Austin Seven model Handbook simply suggests turning the dynamo off during summer from time to time (the Lucas SM3 switchboard simply switching the field out of the circuit) to not overcharge the battery (I assume you checked from time to time to see if the battery was 'boiling !!)

When the DEL dynamo was introduced, this then incorporated a resistance winding with the field windings, using the 'D' terminal as before but the second terminal now designated 'SH' for shunt which is connected to the resistance and thence to the field windings. The dashboard is also now fitted with the new improved Lucas SM5 switchboard with two charging positions- summer and winter. The summer position includes the shunt resistance in the field circuit reducing the charge rate, the winter position bypasses the resistance increasing the charging rate.

For simplicity I usually connect the D and SH terminals at the dynamo giving full charge at all times and removing any problems with faulty shunt windings. I drive with the sidelights on during the day to soak up any extra charge (emulating all the moderns with their Christmas tree lights)

Hopefully this hasn't confused the debate!

Tony.

Location: Malvern, Melbourne, Australia.

Re: DEL Dynamo help

Tony Press
For simplicity I usually connect the D and SH terminals at the dynamo.


Me too, has worked a treat for over a quarter of a century now.

Re: DEL Dynamo help

Thanks for replies so far!

Well i've tinkered around now quite a bit to try and get it to work properly and can get an adjustable (on the 3rd brush) charge, but still no summer charge, so it's looking like resistance windings, even though when running as a motor on the bench with the resistance wire off, then attaching it to D you get a speed change. Must be something stupid right under my nose!! I'm no rivet counter but i like to know why it won't work properly even if it never does!

Location: Moonraking in Wiltshire

Re: DEL Dynamo help

Hi Ian and Tony

I know the general set up but the mystery is (assuming the Cornwall dwg is correct) why does the resistance connect to the junction of the 1st and 2nd (of 4) field windings?
Austin must have had some basis for adopting the resistance as a winding etc. I am curious to know how the connection is made without another terminal. Resistance wire usually does not solder.

It is rather like the mystery of the later field fuses, which, contrary to what all the books state, do not prevent charging if blown, nor protect the field, but seem to protect the Summer resistor, which does not strand a motorist even if burned out??

It seems a pity to abandon the Summer facility entirely. A relentless 8 amps is a lot on a trip. And with D and F directly connected an external wiring breakage may cook the dynamo.And the less the skew gears have to do the better.

Bob Culver

Location: Auckland, NZ

Re: DEL Dynamo help

Not sure what you mean here-

"I know the general set up but the mystery is (assuming the Cornwall dwg is correct) why does the resistance connect to the junction of the 1st and 2nd (of 4) field windings?
Austin must have had some basis for adopting the resistance as a winding etc. I am curious to know how the connection is made without another terminal"

Isn't the resistance (which is wound with the field coil) in series with the field coils which are fed from the 'D' terminal until shorted out when the SH and D terminals are connected??

I don't know what the resistance wire is, but I assume that it is not incompatible with the field wire.

"It seems a pity to abandon the Summer facility entirely. A relentless 8 amps is a lot on a trip. And with D and F directly connected an external wiring breakage may cook the dynamo. And the less the skew gears have to do the better."

As I noted I always have the side and tail lamps on during daytime running to use up the charge. The skew gears seem to be robust and lubricated with engine oil which has an antiwear additive.

Tony.

Location: Malvern, Melbourne, Australia.

Re: DEL Dynamo help

Further to earlier discussions I have been reading through a bound collection of A7CA Magazines from the late 70's early 80's recently given to me.
Fascinating stuff and lots of very good technical advice.

The 1979C issue has a very comprehensive article 'A closer Look at Dynamos, Cut-outs and Switch Panels' by Harry Hales.
This explains everything you need to know about Austin Seven electrics from 1924 to 1937 complete with pictures of switchboards, dynamos, cutouts and a full set of wiring diagrams. This article would pay repeating, if possible.

Apparently a later article in 1979D deals with fault finding and testing together with a list of matching components.

Tony.

Location: Malvern, Melbourne, Australia.

Re: DEL Dynamo help

Tony if you do a search you will find that Ruairidh kindly posted this article for me a few months ago.

Location: NZ

Re: DEL Dynamo help

I plead old age and incompetence! (it was over six months ago !)

If you search on 'dynamos' it can be found under the slightly obscure heading of 'A7CA Articles' -

http://pub25.bravenet.com/forum/static/show.php?usernum=2099944454&frmid=5&msgid=984123&cmd=show

I think this (and others) still need to be republished - maybe on the new A7CA website under a section titled 'Historical Technical Articles from the A7CA magazine'

Tony.

Location: Malvern, Melbourne, Australia.

Re: DEL Dynamo help

Just read that article! A really great help!

Location: Horsham

Re: DEL Dynamo help

Thanks fellahs

I had forgotten about that posting.... but it still does not explain why the resistor bypasses one field coil Fig 11, or how the internal connection is made! Perhaps it was reasoned that two sources of heat would have been too much, even with reduced field current? or is the drawing wrong and repeated in the Cornwall article?

Bob Culver

Location: Auckland, NZ

Re: DEL Dynamo help

Richard

sounds very much to me like as failed resistance which as everyone has pointed out, is wound in to the field coils on the del dynamo, rather than external, like the later ones. You should be able to test the resistance with a multimeter on the small summer charge terminal. As far as I know no one rebuilds these dynamos
with the resistance wound in to the field coils as original .

Nick

Re: DEL Dynamo help

There are winders that will do the complete job on a DEL type including the resistance in the field coils. They often need persuading to do them. Most cannot do this sighting that they cannot get the wire, which is misleading.

Armoto will do them and I have had good work from them including DEL dynamo full rewind's as original.
Adam Kennedy is very knowledgeable and is happy to chat your needs through with you. Interestingly they will do the job to whatever standard you want. For example working "oily rag" or concours - nickel plating ect.
Unlike a lot they do the whole process in-house.

Here is their URL :-
http://www.vehicle-electrical-rewinds.co.uk/

Hope this is useful.

Location: The Centre of the Universe