1981 XL500 blowing head light – OLD Bull Trailriders

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July 24, 2012 at 11:50 pm #101687

Gary Newnham
Member

Hey lads
I have the XL running with new battery& regulator rectifier, nice stable 7.5VDC @ battery.
However Headlight is supplied from its own coil with no regulator/rectifier via yellow/wite wire.
The output from this circuit is 16 to 40VAC depending on RPM.
It simply blows every bulb I put near it any ideas???????????????.
Cheers :unsure:

July 25, 2012 at 2:52 am #226613

Dean
Member

Hey gazza have you got a wiring diagram? I reckon Nick might be able to help ya mate if you got a diagram.

Also you can get those new Cree LED’s Bulbs they are awsome and will shame a standard XL headlight. Also they are not fussy on the voltage applied to them.

hope this helps

Ollie

July 25, 2012 at 3:10 am #226614

Adam Rodgers
Member

Gazza,

I had a 1980 XL250S and it had a 12 volt lighting coil and 6 volts for everything else.

The AC voltage will be high if there is no load too.

Adam.

July 25, 2012 at 4:11 pm #226632

Dean
Member

Just Dug this up on the internerd, maybe some of the Boffins can chime in.

Ollie

July 25, 2012 at 4:32 pm #226615

Greg
Member

gazza55 wrote:

Hey lads
I have the XL running with new battery& regulator rectifier, nice stable 7.5VDC @ battery.
However Headlight is supplied from its own coil with no regulator/rectifier via yellow/wite wire.
The output from this circuit is 16 to 40VAC depending on RPM.
It simply blows every bulb I put near it any ideas???????????????.
Cheers :unsure:

It has to have a rectifier and regulator to convert it from AC to DC and then regulate it to the desired voltage. Above you say it has a DC battery and a its putting out an AC voltage so that needs to be fixed first

edit

Ollie posted the diagram and you can see the rectifier / regulator in the picture, check your wiring and bike out now

TB

July 25, 2012 at 6:06 pm #226653

Dean
Member

Here is the address for the above diagram so you can Zoom in and see it better

http://zorch.maow.myip.org/bikes/wiring/XL250S_XL500S_1979-1981.jpg

Ollie

From my limited electrical knowledge it appears that the regulator/rectifier is faulty (as mentioned by TB)

Thats all it really could be :dry:

July 26, 2012 at 1:10 am #226616

Gary Newnham
Member

Thanks for all the input guys, I have a good Clymer manual with the diagram, these bikes run AC to the headlight and a 12 Volt bulb as it turns out.

The regulator/rectifier in the circuit does not affect the direct suppy to the headlamp, it charges the battery and runs everything else.

But there seems to be no explanation for the increase in voltage over time. Even when rectified, which I did with a bridge rectifier, the voltage is still above 35 VDC.

The one success I have had to date, is to connect this rectified current back to the pos on the battery, in parallel with the headlamp, the voltage stabilises at 12 volts @ the headlamp and 7.5 volts @ the battery :huh:
I think that the battery is acting as a damper as well as providing backpressure against the higher voltage.
This actually works, I have run a 55w driving lamp as well as the bulb AWESOME Light, hope it doesn’t turn into a Roman Candle!!!???

I think only an electrical engineer could explain that?

I am going to test & finalise tommorrow and I’ll let you know the outcome.

July 28, 2012 at 9:15 pm #226617

Gary Newnham
Member

Problem solved :cheer:
At last;
I now have both the XL and the PE ready for rego, just got to save the pennies and we’re on our way.
I now run a 12 volt head lamp and a 6volt 55W driving lamp on the Xl It’s all working great.
I’ve fitted a TrailTech dash, LED numberplate lamp & indicators (6 volt) to the PE.
I fitted 6volt LED indicators (made’m all m’self) & stop tail to the XL as well.
Will upload new pic’s in the next few days of the finished bikes.
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