Author Topic: Unmount Dynamo  (Read 1003 times)

Offline Marc25

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Unmount Dynamo
« on: 24.01. 2015 15:47 »
Hello Everyone  *smiley4*

There's no BSA for Dummies (like me) section in this forum ?  ;)

My A10 plunger is not charging so I first tried the dynamo and it looks bad.
There is no current going out there.

Resitance looks OK.
Brushes looks good.
I used to generator to have an external excitation not better...

So I wanted to unmount the dynamo.
How is it working ?
Do I have to unmount the big "plate" which hides the chains ?

Thanks in advance for your..... lights of course  *smile*

Online bsa-bill

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Re: Unmount Dynamo
« Reply #1 on: 24.01. 2015 16:43 »
Quote
There's no BSA for Dummies (like me) section in this forum ?[/quote
no need - most of us come in to that category some of the time  *smiley4*

You seem to have covered the most obvious things , I presume
Quote
I used to generator to have an external excitation not better...
means you flashed the dynamo, usually done from a battery, important you get the right polarity - search for "flashing" using the search feature (between HELP and PROFILE)

It may be possibly to remove the dynamo without taking off the timing case but you will need it off to refit it so might as well remove it first, you might find a broken chain
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline bikerbob

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Re: Unmount Dynamo
« Reply #2 on: 24.01. 2015 16:54 »
 Are you sure you have tested the dyanmo correctly. Because not charging could also be down a faulty regulator. To test the dynamo first disconnect the 2 wires going into the dynamo then insert a link wire between the 2 dynamo terminals then using a voltmeter or multimeter insert one lead into one of the dynamo terminals it does not matter which one as they are now linked then put the other terminal to earth. With the bike running on tickover you should get reading of 1 or 2 volts increase the engine speed to about 1000 revs then you should get a reading of 7 or 8 volts but do not rev the engine higher to get  a result.
 If you wish to remove the dynamo first disconnect the 2 wires the on the opposite side remove the gearchange  lever place a tray underneath the timing side case  to catch the small amount of oil that will come out remove the bolts holding the timing side case. You will then see that the dynamo is driven by an endless chain, slacken off the dynamo clamp bolt and you will be able to turn the dynamo to slacken the chain you may be able to get the chain off the sprockets if not you will have to remove the dynamo sprocket this is on a taper and could be a tight fit. After this you should be able to pull the dynamo out from the drive side you will have to twist it to remove it.

Offline Marc25

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Re: Unmount Dynamo
« Reply #3 on: 24.01. 2015 17:01 »
Thanks !

Yes your solution for testing works, it is an auto-excitation. (well at least in french ;) )
I went for an external excitation but the idea is the same.

I'll go for unmounting the timing side case  *smiley4*

Online RichardL

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Re: Unmount Dynamo
« Reply #4 on: 24.01. 2015 21:05 »
Another alternative is to remove the large sprocket that drives the dynamo. Neither of them is going to come off easily. If you are lucky, your dynamo chain might have a removable link. Be sure to check. My A10 had a removable link but my A7 had the continuous chain.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline Marc25

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Re: Unmount Dynamo
« Reply #5 on: 25.01. 2015 16:32 »
Fiat lux... et lux fuit...

Thanks to all of you.
Indeed removing the cap is mandatory.

It is now lighting a bulb with auto-excitation, so it works fine.
I don't really know the root cause.
Two possible problems : Oil on the brushes, false ground because of the paint.

Now as I am still stupid, what does D and F stands for ?
Which one goes to to the brushes ? Which one to the external coil ?

Offline chaterlea25

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Re: Unmount Dynamo
« Reply #6 on: 25.01. 2015 19:16 »
HI Marc,
"D" is the live brush, it is connected to the yellow wire in the loom
"F" is the field connection, green wire, (remember green field !!!!)

John
1961 Super Rocket
1963 RGS (ongoing)

Offline Marc25

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Re: Unmount Dynamo
« Reply #7 on: 28.01. 2015 13:40 »
Thanks !!