Dynamo not working

General electrical problems
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charles.bulloch
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Dynamo not working

Postby charles.bulloch » Wed May 05, 2021 10:22 am

Hi, all

My dynamo has been flashed to the negative terminal and motors beautifully in the correct direction with a positive earth. Sadly it does not generate a current on the bike between D F and earth. I get 2.6 ohms across F.

I assume the dynamo needs rebuilt. Is there anyone who will provide this service in reasonable time?

Charlie

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BobWard
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Re: Dynamo not working

Postby BobWard » Wed May 05, 2021 11:02 am

I had a problem with my charging system I cleaned up / serviced the Dynamo and fitted a new DVR2P digital regulator and had no success then I was recommended to talk to Paul Dunn of Dynamo Dynamo internet site 01782 856839 in the thoughts that I had done everything I could do and would ship the necessary parts to check and renovate my charging system. Paul Dunn talked me through the charging problems I had and what I should do before the last resort of posting my Dynamo to him. My one track thought of the field windings shorting the system was proved wrong and Mr Dunn’s free advice worked. So I would highly recommend Paul Dunn. Bob. Selly Oak branch, if it ever meets up again :lol:
1958 Huntmaster
1957 VH 500
1960 FB Cruiser 84

Gui.dorey
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Re: Dynamo not working

Postby Gui.dorey » Wed May 05, 2021 12:21 pm

You can try deglazing the brushes before you send it in. I had recently a dynamo that passed all the tests, but wouldn‘t generate current. I then carefully ran a jewler‘s file over the carbon brushes and it worked. Full output.
1951 Ariel Square Four MKI
1954 Ariel NH Red Hunter
1929 BSA Sloper
1946 BSA B31 (project)
1954 BSA C11G
1960 Harley Sportster XLH
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Re: Dynamo not working

Postby JohnnyBeckett » Wed May 05, 2021 8:23 pm

hi also check the dynamo body has got a good earth to the mag or engine, paint on the body can stop it getting a good earth, on my NH i have earth the mag to the engine as well now i get a better spark to the plug and very good charging :D :D

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Re: Dynamo not working

Postby Julian Murphy » Thu May 06, 2021 2:57 pm

Oh, thats an interesting point.

I have just overhauled my dynamo (brushes, bearings) and also painted the body black.

Never actualy thought about earth bonding to the magneto or frame.

Will have a look at that to see if I can make up an earth lead. (One of my clients uses braiding to earth doors to the main earth of the control panels that they manufacture. Will see if I can 'borrow' a bit!)

Johnny.

Have you also earthed the mag to the frame as well?

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Re: Dynamo not working

Postby JohnnyBeckett » Thu May 06, 2021 6:36 pm

hi if you look at a original dynamo the body is cadmium plated to stop it rusting and not painted so the body can earth out i made the mistake of painting my dynamo wen i rebuilt it and it stop it getting a good earthing on the mag :roll:

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alan.moore
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Re: Dynamo not working

Postby alan.moore » Thu May 06, 2021 7:30 pm

Here's what I do with mine:
1. Dynamo body plated, not painted, so it has a good electrical connection with the magneto body.

2. Earth terminal on the magneto bonded to the engine and via a wire to the main earthing point on the frame under the seat

SDC14358.JPG


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Alan
1939 VH Redhunter;1942 RN WNG;1951 Triumph 6T Thunderbird;1970 BSA B175 Bantam;1986 Yamaha SRX600 single
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alan.moore
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Re: Dynamo not working

Postby alan.moore » Thu May 06, 2021 7:33 pm

BobWard wrote:I had a problem with my charging system I cleaned up / serviced the Dynamo and fitted a new DVR2P digital regulator and had no success then I was recommended to talk to Paul Dunn of Dynamo Dynamo internet site 01782 856839 in the thoughts that I had done everything I could do and would ship the necessary parts to check and renovate my charging system. Paul Dunn talked me through the charging problems I had and what I should do before the last resort of posting my Dynamo to him. My one track thought of the field windings shorting the system was proved wrong and Mr Dunn’s free advice worked. So I would highly recommend Paul Dunn. Bob. Selly Oak branch, if it ever meets up again :lol:


Bob,
What was the advice from Paul Dunn that got your system working?
1939 VH Redhunter;1942 RN WNG;1951 Triumph 6T Thunderbird;1970 BSA B175 Bantam;1986 Yamaha SRX600 single
http://cloggymoore.wix.com/triumph-pre-unit-6t

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Re: Dynamo not working

Postby Julian Murphy » Thu May 06, 2021 8:59 pm

Well, I never knew that was an earth point on the magneto.

I did run a seperate earth to the headlight to avoid trying to earth through the greasy steering head bearings.

Looks like I will be stripping part, or all of the fresh satin paint just sprayed onto the dynamo body. Looks so good as well. :shock:

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Re: Dynamo not working

Postby BobWard » Fri May 07, 2021 1:26 am

Alan.Moore having informed Paul the ammeter read —4 amps with high beam switched on battery only he said “That is a problem being either a short to earth or wrong rated headlight bulb or battery amp hour too small and if your friend has ridden the bike like that for long periods of time it will of cooked the armature.” The headlight bulb on dip or beam was very very bright ( I was quite chuffed ) so I swooped it with a Paul Goff Led and have only done a 10 mile round the block trial so not had a long enough run to see if the armature breaks down, hopefully as suggested the DVR2P thermal cutout was the reason for the quick loss of charge while running in the garage.
1958 Huntmaster
1957 VH 500
1960 FB Cruiser 84


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