Charging issue

Discuss all things 1970 & later Airheads right here.
geepeetee
Posts: 14
Joined: Tue Aug 06, 2024 4:03 pm

Re: Charging issue

Post by geepeetee »

Hi.

Also an image of the dash internals, it wouldn't let me add another to the previous post. It looks in good order, i can't see any faults.

Cheers

Gary
Attachments
Dash internals
Dash internals
20240809_081637.jpg (326.62 KiB) Viewed 337 times
geepeetee
Posts: 14
Joined: Tue Aug 06, 2024 4:03 pm

Re: Charging issue

Post by geepeetee »

As we look at the image above i identified the top left pin as 12v supply for.the warning lights and on the right,
3rd from top is gen lamp
5th is oil.

I used the corresponding holes in the connector for the tests in previous images
Rob Frankham
Posts: 1213
Joined: Thu Aug 26, 2010 2:11 pm
Location: Scotland UK, 20 miles from civilisation up a dead end road!
Contact:

Re: Charging issue

Post by Rob Frankham »

Measuring between the bulb terminals isn't really a good test, you get much more information by testing between the various points and ground. It is also important to carry out many tests with the load attached. If you work though the tests I suggested in the previous post you can be pretty sure to isolate the area of the fault.

Rob
ImageImageImage
geepeetee
Posts: 14
Joined: Tue Aug 06, 2024 4:03 pm

Re: Charging issue

Post by geepeetee »

Hi Rob

I couldnt see a way to.test the with the bulb in place initially but.have put he dash back.on without.the.bottom cover and.could just get the probes in, getting 11.9v both sides (one.shows -11.9v) when i put other probe to bare metal, bulb still not working, i have tried.the bulb and holder in another socket and works.ok.

Shorting the negative.side.of.the bulb doesnt light it.

The 3 VR tests dont light the bulb

The brushes appear have good pressure to the slip rings when lifted slightly with a small screwdriver.

How do i check the continuity of the rotor?

Thanks

Gary
User avatar
gspd
Posts: 1041
Joined: Tue Aug 03, 2010 8:04 pm

Re: Charging issue

Post by gspd »

geepeetee wrote: Fri Aug 09, 2024 6:28 am How do i check the continuity of the rotor?
Isolate both brushes from the rotor with a piece of paper.
With your DVM, open circuit or short circuit between the slip rings is definitely a failed rotor.
Should be roughly between 3 and 7 ohms resistance between slip rings. The exact reading is not critical.
Rotors usually fail from becoming open circuit (full short circuits are very, very rare).

As far as your tests go, I would ditch the DVM and test your dash wiring plug circuits with a old style incandescent test light.
Connect the test light to battery negative to check any power circuits,
connect it to battery positive to check any ground circuits.
Once you're familiar with your test light, it's actual intensity will reveal if a circuit is compromised.
If everything works at the plug, the printed circuit is the problem.
This printed circuit is all old school analog so it shouldn't be too difficult to pinpoint the failure, if there is one, between the pin and the bulb contact foil.

That 4.5v reading you were seeing is really weird, maybe RobF can provide an explanation?
Testing between the wrong pins? Partial short in plug or main harness?
Mechanic from Hell
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
geepeetee
Posts: 14
Joined: Tue Aug 06, 2024 4:03 pm

Re: Charging issue

Post by geepeetee »

Hi

Resistance between slip rings is 3.5 ohms.

Thinking about the no gen light on any of the tests, i decided to loop a wire around the 0v side of the gen lamp terminal and refit the dash. Lamp works nice and bright when i ground the other end. I havent run the.bike because tanks off so I dont know the charging situation.

Guess i need to find the fault causing the light not to work before i move on.

Thanks again.

Gary

Thsnks

Gary
geepeetee
Posts: 14
Joined: Tue Aug 06, 2024 4:03 pm

Re: Charging issue

Post by geepeetee »

Sorry, back again

Looking at my haynes wiring diagram it shows the blue 0v from the lamp joins a wire from D+ on the diode board to D+ on the VR.

The blue on my VR has another joined into the terminal (blue with a stripe i think), would i be correct in thinking the solid blue one is from the gen lamp?

Just trying to pinpoint where to look next.

Cheers

Gary
User avatar
gspd
Posts: 1041
Joined: Tue Aug 03, 2010 8:04 pm

Re: Charging issue

Post by gspd »

geepeetee wrote: Fri Aug 09, 2024 8:46 am Thinking about the no gen light on any of the tests, i decided to loop a wire around the 0v side of the gen lamp terminal and refit the dash. Lamp works nice and bright when i ground the other end. I havent run the.bike because tanks off so I dont know the charging situation.
Sounds like the blue wire is not getting ground at the regulator.
Rob's suggested tests should determine that.
Go to the voltage regulator. Remove the connector and use a pirece of wire to short the blue wire to ground. If the bulb lights, it proves that the wiring from the bulb to the voltage regulator is sound.
Short between the blue wire and the brown wire on the regulator connector. If the bulb lights it proves that the earth connection to the voltage regulator is good.

Possibly a faulty regulator?
FYI - The only 1000% reliable regulator test is to substitute it with a known 'good' one.
Mechanic from Hell
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
geepeetee
Posts: 14
Joined: Tue Aug 06, 2024 4:03 pm

Re: Charging issue

Post by geepeetee »

I completed the tests at the regulator, done them a few times because i keep doubting myself : ) No gen light for any of them. Only thing that worked is the jump wire from the dash to ground.

Could i have a bresk in the blue wire from the gen light to the VR?
User avatar
gspd
Posts: 1041
Joined: Tue Aug 03, 2010 8:04 pm

Re: Charging issue

Post by gspd »

geepeetee wrote: Fri Aug 09, 2024 9:11 am I completed the tests at the regulator, done them a few times because i keep doubting myself : ) No gen light for any of them. Only thing that worked is the jump wire from the dash to ground.

Could i have a bresk in the blue wire from the gen light to the VR?
With the VR and dash unplugged, check for continuity between the blue wire at the regulator at its pin at the dash plug.
Mechanic from Hell
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
Post Reply