Author Topic: Ammeter showing no charge - 'Flash' dynamo?  (Read 3702 times)

Offline RoadRunner

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Ammeter showing no charge - 'Flash' dynamo?
« on: 24.07. 2011 22:20 »
Hi,
Finally got the A7 plunger fired up - most is well but the ammeter shows no charge. From previous threads I understand I probably need to 'Flash' the dynamo? Its wired as positive earth so presumably I can do this after disconnecting the 'F' & 'D' wires connected to the regulator and flash the 'F' wire with the battery negative wire rather than flashing at the actual dynamo end?

Two daft questions - engine doesn't need to be running does it when 'flashing' and as the engine (1.2 miles only so far!) has run will the voltage regulator be trashed?

Cheers
RoadRunner



Offline trevinoz

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #1 on: 24.07. 2011 23:28 »
RR,
          You don't say what type of regulator you have.
As to the need to flash or not, the first test should be to see if the generator is actually working.
The test procedure is well documented here but remove "D" & "F" wires from the generator, bridge the terminals with a piece of wire, connect a voltmeter to the bridged terminals with the negative lead and positve to earth. A digital meter is best as you will be able to see what polarity the output, if any, is.
Run the engine and you should get over 12V pretty smartly.
If polarity is reversed, flash the field.
This test can be done at the regulator as you describe, probably easier if you have a generator with the pressed metal end cap.

  Trev.

Offline wilko

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #2 on: 25.07. 2011 00:10 »
Then report back!

Offline RoadRunner

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #3 on: 25.07. 2011 12:07 »
Thanks guys - RR reporting back!

I'm no electrician - hence connected red
  • lead to earth and black [-] to bridged dynamo wires (yellow/green) and got a reading of 9.0v - 17.0v on a digital ammeter depending on revs. Largely it settled around 9.0v -11.0v ish without overreving (new engine rebuild).


So the dynamo is kicking out the correct voltage on the correct polarity?

As for voltage regulators, yes, I'm afraid so, I'm using one of those foreign replacement things instead of a genuinue Lucas one - thought being a new one should work?? (naive - yep certainly am!) - same with the ammeter.

I do have an original Lucas V/regulator but no idea whether it works or not or if it came off a working bike.
My wiring is all new - bought harness and connected/modified up by myself - everything else (lights) has worked first time.

Possibilities - duff V/regulator and/or duff ammeter or duff wiring?
Any suggestions on checking the above or otherwise??

Cheers
RoadRunner

Online bsa-bill

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #4 on: 25.07. 2011 12:54 »
maybe a need here to get some basics Roadrunner

First - with the engine stopped and the lights on what's on the Ammeter - should show discharge

Engine running with a full battery - should show no charge
now with engine running - switch on lights - should show discharge then creep back up to a little less discharge

With an older battery with engine running - should show charge then creep back to middle

let us know what happens with each of those
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 RoadRunner

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #5 on: 25.07. 2011 13:13 »
Cheers Bill,
Back to basics it is - I'll endevour to get on with it while the weathers' good and report back ASAP! Meanwhile here's a pic. 

Offline RoadRunner

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #6 on: 25.07. 2011 14:16 »
Hi Bill,
In response to the checks - with the engine off and lights on the ammeter needle doesn't appear to move; presumably I'd see quite a drop with the needle moving deep into -ve? With lights on and then putting the brake light on and using the horn doesn't change the status in the needle position as shown in the pic below.

With engine running there is no change either in the needle postion even when revved - not a flicker.

Oh, using two solid state 6v batteries wired togther for a 6v output; these are new and been checked to give out around 6.3v.

Cheers
RR



Offline wilko

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #7 on: 25.07. 2011 21:11 »
For a start junk the repro reg, as they are junk, and follow the output "A" from your reg , it should go to the minus side of your ammeter and all other ancillaries and battery to the "plus" side.If your old reg is complete and not butchered, just give the points a clean up with some fine emery paper and then another wipe with some contact cleaner. My old original reg has been working for 7 years with no other adjustments.

Offline t20racerman

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #8 on: 25.07. 2011 22:14 »
Cheers Bill,
Back to basics it is - I'll endevour to get on with it while the weathers' good and report back ASAP! Meanwhile here's a pic. 

Wow, lovely looking bike!  *smile*

Alternatively get a new solid state regulator from here:

http://www.dynamoregulators.com/

Ordered mine today.
All the best
Adrian
1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Online bsa-bill

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #9 on: 25.07. 2011 22:24 »
I have a solid state reg I bought from Paul Goff, defo not junk, works fine, if BSA made bikes today these are what they would be using.

Wilko's comments re the wiring are the next step to check.
Lets not ignore a duff ammeter although they seldom seem to give trouble, is it a known to work ammeter
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 trevinoz

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #10 on: 26.07. 2011 00:46 »
I agree with Wilko, to a point, about the repo regulators.
Usually the regulator points are dirty when bought.
I set them up as per Lucas instructions and mostly they work OK.
There appears to be more than one manufacturer of these regs.
One type has too coarse a thread in the adjusting screws and makes it difficult to accurately set the reg.
A quick test whether the regulator points are dirty is to set the meter on "ohms" and test between "D" & "F" terminals on the reg with the external wiring disconnected.
You should get a very low reading, something like you get when you touch the leads together.
Ensure that the meter is set on the lowest scale, usually 20 ohms.

  Trev.

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #11 on: 29.07. 2011 21:05 »
Up the creek without a paddle now springs to mind *problem*. Talk about stupid questions - here goes....

Went back to basics and checked the dynamo was turning and that the yellow and green wires were connected to 'D' and 'F' respectively at both the dynamo end and v/regulator - all okay.
Checked the purple wire [A] from the v/regulator to the -ve post on the ammeter for continuity - all okay.
Ran the bike and switched lights on etc and no movement on the ammeter.

So - took off the 'new' v/regulator and replaced with a genuine one; switched the lights on, rear brake and horn all together and the ammeter showed no movement. Ran, revved the engine still no joy.
Disconnected the purple from the ammeter, ran the engine and checked the voltage [not sure that was a good idea] since the ammeter now shows -8amps permanently. Upon further checking it's blown the 25amp fuse between the v/regulator and the ammeter (too smaller fuse?).

Re: "A quick test whether the regulator points are dirty is to set the meter on "ohms" and test between "D" & "F" terminals on the reg with the external wiring disconnected."

I set my digital m/m to 200 (the setting below 2k) in the ohms sector and got a reading of 0.7 on the green and yellow wires - touching the digital m/m probes together gave me 0.2?

Then went to bridge the dynamo yellow and green and earthed the positive with engine running and didn't appear to get the same reading as last week [?] Now I'm beginning to doubt the digital multimeter!
So I'm going back to basics again and resorting to the bulb test on Sunday and see if it lights up and gets bright upon revving using a 12v 21 watt bulb.

From the above I take it I've destroyed the ammeter with my amateur/lack of electrical knowledge?? Any ideas? I can't really afford a new digital v/reg, and who sells decent/real ammeters since I'll probably need one?

How do I check the output from the v/reg - m/meter the purple wire [A] with the -ve probe and m/meter the earth the +ve probe? Presumably its voltage it kicks out (please excuse my ignorance)

Some what frustrated - should have continued running on the lakeland fells yesterday!!!

Cheers
RoadRunner

Online bsa-bill

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #12 on: 29.07. 2011 21:32 »
Just a thought Roadrunner
There should be two wires one side of the ammeter, wire from vreg to ammeter and on the same post a wire to the switch position 3
And on the other post one wire to battery negative .
In practise sometimes other feeds taken off the ammeter but the above three need to be right.
Also check that the earth (E) from the vreg is OK and making good electrical contact with the frame

Ammeters are usually pretty rugged, also my vreg coped with a bit of abuse and still works fine (someone who shall remain nameless managed to get the green and yellow crossed)
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 RoadRunner

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #13 on: 29.07. 2011 23:15 »
Thanks Bill,
You're correct, I do have a second [purple] wire going to position 3 on the switch - only 1 brown wire on the +ve post of the ammeter; but will check it goes to battery -ve.

Just going to have to sit and go about it logically rather than rushing - which I'm guilty of! 
Many thanks
RR

Offline trevinoz

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Re: Ammeter showing no charge - 'Flash' dynamo?
« Reply #14 on: 30.07. 2011 00:25 »
RR,
           You need to disconnect the wires from the reg before you test for continuity through the contacts.
Have you tried testing the voltage across the battery with the engine running?
If you have a crook ammeter it should still have a circuit through it thus allowing current to flow but not indicating same.

  Trev.