1933/34 dynamo cut-out

[Tony Fearn]

I'm having a problem with the cut outs on my 1933 Flying Fox, and my 1934 Short saloon.
They seem to 'warm up' on the road, having been useless for 8 or 10 minutes in to a drive, with no charge showing, either on the Summer or Winter setting.
The ignition light stays on up to this point, and then everything's OK, with a charge showing on the ammeter.
Will they be OK in the future, or will there come a time when they won't work again, and the battery will slowly drain voltage as I tootle along?
I remember Barry having his sorted by Paul, and perhaps this is the way to go.
If necessary this is what I'll do, but is it easy to re-attach the wires coming out of the dynamo into the 'electronic' cut-out, and will the three wires going from the cut-out into the loom not need altering?
Tony.

[AlanBartlett]

Tony,

This is exaclty what happend with mine at the end of last year. When I put the topic up about I know I havent resolved the problem either. It seemed to cure itself on certain runs out. Not wanting to resort to major tinkering of taking everything apart. I have left it for now. (It worked well enough for the 400mile revival work) Perhaps others can shed some light. Knowing it will eventually kick in. Just an un easy feeling staring at the still lit warning light.

[BarryCambs]

The solid state cut outs are very cheap and easy to fit. I think this is the one fitted to mine.

http://dynamoregulators.com/cutout.php

My cutout was shot and it didn't seem worth trying to find a second hand one that might not be an better. I didn't realise, but inside the thick coil around the solenoid is a second winding which uses the very fine wire (same as that around ignition warning lamp), which is impossible to solder or do anything with. I think it was going to be well over £100 to have it rewound. It fits neatly in the original case, so I don't feel too guilty about it.

Barry

[Tony Fearn]

Hello Barry.
Please will you post a photo or three of the solid state cut-out placed inside your original cut-out unit.
Have all the original innards been removed?
Thanks.
Tony.

[AlanBartlett]

Having just done a run in mine over the weekend. The dynamo has stopped charging over 60 mile run. Where as before it would eventually "kick in". Has there been anymore thought on this?

[Forumadmin]

I do not know the details of the cutout you have but since it is probably a mechanical relay the symptoms suggest a few possible reasons.
A meter would be useful!
If the contacts are accessible and visible then measure the resistance across them, preferably with battery disconnected.
At rest the contacts should be open and should close when the dynamo generates enough voltage.
If you press the contacts together you should see the resistance go to zero. if it does not then the contacts will need cleaning or replacing.
Of course, if the battery is still connected then it will try to drive the dynamo, so you would see an arc across the contacts and if the drive belt is not connected the dynamo will turn.
if you set the meter to volts then depending on if 12 or 6v you should see that voltage on one side of the open contacts with the engine at rest and the battery connected. On the other side of the contacts you should see the dynamo voltage which should rise above the 6 or 12 v when the engine is not idling. Normally the relay can be adjusted to specify at what voltage the cut out will cut in.
If you have a lamp (often called the ignition light) across the contacts then this should go out once cut in voltage is reached.
Some later cut outs have voltage compensation added using a bimetal strip that tensions the contacts via the cut in voltage screw adjuster.

The intermittency suggests to me the contacts are worn, oxidised or possibly have a dry joint in the circuit.
Pass some fine emery between the contacts if you cannot remove them for a good inspection and cleaning.
It is also possible that the screws holding the contacts are loose.
If you do not have battery voltage on one contact then the series coil on the armature ( the thick copper wire) may be broken.
If the armature does not kick in then the shunt coil ( the fine wire coil) may be open circuit.

[BarryCambs]

Just reading this, I realise I missed Tony's request for a picture of the electronic cut out fitted in the case. Tony - as you can see, the entire original relay has been removed, but the external appearance remains the same.

IMG_3865.JPG

As an aside, if anyone has a broken cutout, I'd be very happy to give it a home, as I'm trying to put a spare dynamo together and I can put an electonic module in it.

[Keith Clements]

I have just read that cut out contacts are made of silver and should be cleaned with fine GLASS paper and voltage regulator contacts are tungsten and should be cleaned with fine EMERY/carborundum.

Hope you sort he burnt out wires Alan!

[Dhbangham]

I can confirm that Paul at Powersmart repaired my original regulator very well indeed. He kept suggesting that I did the sensible thing and use an electronic device, but since he offered to repair it, I took up his offer. I have just tried contacting Paul, to check he is still in business, but as yet I have not had a reply. I hope he is.

[BarryCambs]

I spoke to Paul on Thursday and he's very much still around and very busy!

[Dhbangham]

excellent new, thank Barry.

[Dhbangham]

Interesting information from Keith about contact surfaces and how to clean them. Recently 3M have introduced a new generation of emery/abrasive sheet with smooth plastic sub straight called micron paper, which I now use at work for many applications. You can read more about it here: https://www.cousinsuk.com/category/micron-paper-3m (I am not promoting the retailer, they were the first page I found with info) The advantage is that the backing is very smooth and the abrasive is very tightly bound to the backing, so there is virtually no risk of leaving grit behind. Scotch bright is also very useful, though not for point contacts.

[Forumadmin]

Hello again Barry,
A very long-time Jowetteer friend has had a dynamo restored for me for a Christmas present.

001.JPG

This includes an electronic module similar/same as yours which you can see in the above photo.
He is also going to have one restored for himself, but finds the electronic modules are now an out-of stock item, with perhaps no future ones being available.
I just wondered if anyone out there has any idea if they might be obtained from other sources.
Tony.

[Forumadmin]

Hello Tony,

What is the number printed on the regulator, there are often alternatives? I may be able to source. The PCB does not look very complex.
by Alastair Gregg » 19 Jan 2019 03:02 pm

[Forumadmin]

Post by BarryCambs » 19 Jan 2019 07:28 pm
Hi Tony

I checked on the website and it does say unavailable for some reason. Seems a bit strange. Everyone else just seems to do combined cut out/regulator

As Alistair says, it's basically one chip which is some sort of diode, so I'll have a look on mine and see if I can see the number.

It might be worth ringing Paul at Smart Power to see if he has any in stock too. 07747 830444 There are a positive and negative earth version. They do work really well. My only slight issue is while the dynamo puts out the specified 8 amps when underway, my halogen bulbs draw 10amps! I know Daniel has LED in his, but I'm waiting on fitting the correct headlights before I worry too much. I've been offered a couple for free, but they are in Cornwall and I have to help respray an old Zephyr before I'm allowed to have them.