Forum

[pilot]

Hi,
I fitted an aftermarket headlamp to my ac powered headlamp and spent ages finding an electrical fault that caused all sorts of problems. Turned out that the ac earth to the headlamp (not an earth as such) was connecting to the battery through the bike frame. Worth checking that the ac system is isolated from the dc system. I had to isolate the headlamp bulb to prevent it contacting the headlamp shell as it was shorting through the chrome mirror glass to the dc earth. This if not corrected will send 12v ac into the dc earth wire so fecking up electrics.

Pilot.

[Adrian]

Now that is a weird one. What make of headlamp unit was it, and what sort of bulb did it have?

A.

[pilot]

Hi Adrian,
I fitted the 1950ties style headlamp with lucas switch as supplied by hitchcocks. I think the 2 wires from the ac regulator should be connected to the two terminals of the bulb through the switch direct to the bulb and have no contact with the dc system. AC power is a push pull power system and may interfere with the dc system as in voltage getting into the bike earth. Cant remember what bulb was 8 years ago.

[Adrian]

LU/51829 (Pattern)? ISTRC if it's a pre-focus bulb the earth comes off the bulb fixing cap which fits onto the metal sleeve of the bulb holder, so I can see how that might have caused your problem. H4 bulbs have the three blade terminals at the back, one each for main, dip and earth (or AC return in you're running it on a post 1999 Bullet). The bulb is fastened by a spring clip and the three wires are usually in a plastic block with the female blade terminals to push onto the bulb. That sounds like a much better bet for running AC headlights than having to insulate a pre-focus bulb holder. You'd probably get a better beam from a good H4 unit than a pattern pre-focus one.



How did you wire the 50's pattern switch to keep AC and DC apart?



https://www.ebay.co.uk/itm/12V-20A-Meta ... 3d31e3220c



A.

[Adrian]

Sorry 'bout the unexplained link. Bad editing while rushing to post with dinner imminent!



That's for a double pole switch which might be an option for controlling the AC and DC lighting off the same switch, AD down one side and DC down the other.



A.

[pilot]

Yea there's enough terminals on the switch to isolate the circuits.

[pilot]

You right about pre focus bulb. I don't think there's a suitable bulb that fits that headlamp.

[Adrian]

A new 7" H4 headlamp unit isn't that dear if you want to swap over, just wire in the H4 connectors and re-use the chrome rim and clips (be careful taking them out and re-fitting, mind your eyes!).



I just bought one of those repro 50's headlamps, but the pre-focus light unit won't be staying in it. Our hosts sell a couple of different makes of H4 reflector units, though if you're looking elsewhere I'd advise against the Wipac Quadoptic, as the bulb mounting doesn't seem up to Bullet vibrations.



A.

[Super45]

Applogies for the delayed response

Standard Minda headlamp on my bike

yes Vince Typo sorry!

More investigation was caried out on saturday seeing as it was a barmy 16 degrees!

went to diconnected the Amp metre to find the wires are the wrong way round so it was reading in reverse ??? dont remember ever disconecting it so it may of been that way for a while. disconnecting it and plugging in the multimetre showed either a rapidly fluctuating current as numbers didnt much move from 2-3 amps which would explain the wild fluctuations of the amp metre or low ampage of 2-3 amps.

Bike cuts out when the ampmetre is disconnected so suspect this is normal??

then looked further into the wiring in the back of the casquette.. and swiftly wish I hadnt....

1 black connector is there with no matching socket to use, cant see anything on the back of the ampmetre or the speedo or from the handlebar switches it would correspond to, several empty spade connectors with again no sign of a partner, only one that did was a bullet connector which when connected made the ampmetre dive to the farthest corner of the red zone when you switched the pilot lights on so that was swiflty disconnected again!!!

[Super45]

should say amp metre is a standard one with a while female connector but the wires that plug inot it from the battery are connected to it via 2 space connectors on sperate wires which seesm a bit of a bodge