Ever seen a headlamp bulb go short circuit?

[BusterGonads]

A bit weird this....

I was pootling about on my improving year 2000 CG125 yesterday and I noticed my indicators were playing silly buggers. They were flashing at high speed and the silly little kick start only battery was flat. I stopped at the road side and fiddled about with the flasher unit which has been dodgy before until I resoldered a cracked joint in it where the pins join onto the electronicky board inside it. Anyway while I was fiddling with the motor running, I discovered that the problem was with the headlight. If I left it on main beam everything came good, but if I switched to dipped, the headlight went down to a tiny dim glow and the rest of the electrics were starved of volts. I rode it home and dismantled the headlight.

The problem turned out not to be some frayed wire, but the bulb itself. I think it is an S2 halogen type.

Normally I would test the resistance on my multimeter, but that went Kaput the other day. just ordered a new one from fleabay.

I suspect that if the headlamp had been supplied by a battery system and not a puny 35 watt generator, the bulb short would have blown open circuit, but the generator couldn't do that and has just been pumping it's all into a dead short and drained the already poor battery flat through the indicators and stop and tail.

I connected the bulb across a battery charger and while the main beam worked as it should the other one went off with a little flash and then went dead.

I didn't think bulbs failed in this mode usually, but maybe I've only seen it because of the funky cg125 direct lighting system.

[blurredman]

Happened to me on my MZ 250.

Standard Tungsten 40/45 bulb.

Started it up in the night for a ride, lights on, then i thought I would test both beams and realised the beams didn't change.

Opened it up to find the low beam prong had fused with the high beam prong, by somehow bending towards it.

Thought it was cool.
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CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S.
Current: 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (bored to 295cc) - 38k, 1990 MZ ETZ251 - 49k, 1979 Suzuki TS185ER - 9k, 1972 MZ ES250/2 - 17k.

[Islander]

Bulbs can fail short circuit.

[wristjob]

if your bulb is in working condition it will also test short.
thats how they work.

[Kris]

Yep had similar with a stop/tail bulb which was permanently on due to filaments touching.... which of course I found after dismantling the back end of the bike...
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www.prisonplanet.com

[BusterGonads]

Thanks for teh confirmation that this does happen. Ive just never seen it before.

Put an order into WEMOTO this morning and the new bulbs are on teh way. I've ordered two headlamp bulbs, a stop and tail and a spare indicator bulb.

I have a hankering to make the headlight LED. I know the headlights on the CG are AC and LEDs need a DC supply, but it is easy to make a rectifier out of a few diodes of suitable power rating. They cost pennies really and a nice 100uf capacitor would be needed too. I could knock up a 50 Watt rectifier for a very small number of doubloons...

I would only need 4 of these but they come in a pack of ten for £4.10


https://uk.rs-online.com/web/p/rectifier-schottky-diodes/7514843/

I have suitable capacitors lying about and the whole thing would easily fit into the space at the back of the headlight.

Circuit:

https://www.elprocus.com/wp-content/uploads/2015/01/21.jpg

[Nobby the Bastard]

https://www.bikechatforums.com/viewtopic.php?p=4555313&highlight=#4555313
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[BusterGonads]

It's not rare at all. I just never came across that before.

Cheers...

[Nobby the Bastard]

[Islander]

[WmY]

(quotes munged):

I'd never come across before. It does explain why 240v bulbs have a fuse in them though....[/quote]

And why incandescent bulbs occasionally trip a breaker when they fail.

I've never seen a 240V incandescent with a fuse, or short-circuited. They tend to draw large currents when the plasma generated as the filament breaks, and an arc is thus sustained which throws "modern" MCBs. Occasionally splashes of hot metal will melt themselves into the bulb's glass, like angle-grinder sparks.

[WD Forte]

[BusterGonads]

[WD Forte]

I've doing similar rectumfrying and bodgineering on a wee mobylette recently

here for gory details
https://www.bikechatforums.com/viewtopic.php?t=324407

and the voltage can easily go above 18V even on that puny little thing
so I'd suggest some testing before using your new leds on it

I half wave rectified and built a 6VDC reg/rec to run leds on it which work pretty well but as they use a fraction of the current bulbs do
you may need to dissipate some of unwanted powah
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bikers smell of wee

[stinkwheel]

It is possible that an LED headlamp designed for POSITIVE EARTH systems would work with AC lighting.

I intend to do some experiments on this myself in due course. Could work out as an expensive experiment if it goes pop though because the bulbs are around £50 each. I will be using a 12v AC regulator on my AC side.

There is no need to make your own rectifier. You can buy one. Almost all bikes have a reg/rec fitted, most have have three input phases but will work fine with just one or two of them.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Islander]

[Nobby the Bastard]

[WmY]

[BusterGonads]

[bikenut]

Normal bulbs are still used. the cops use the info of/in them all the time in crash investigations, maybe they will "interrogate" ecu's these days........?

The lads bike tended to blow the main fuse quite regularly........I noticed he tended to "attack" speed bumps, and always rode with the headlights on.

My bike, the same model, didn't blow main fuses at all, but I tended not to attack speed bumps........

Anyways, after consulting the wiring diagram and a cuppa, 2 and 2 made 5 !

The headlamp bulb in both bikes was a 410.

The filament support/connection wires in the bulbs, when the bulb is on, get hot. Add a speed bump and then they "bend".

They bend to such an extent that the internal "live " support connection wire touches the earth ( or vica versa I cant remember which now ) and hay presto, the fuse blows.

Since the bulbs where upgraded to the 65w 410 fitting type, this problem no longer happens, the wiring ( which is what the fuse protects remember ) is well able to take the increased load placed on it.

So can bulbs short circuit ?
yes.

They can even fail during an mot test after having been checked and checked and finally check half an hour before the test !

shit happens.
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nuts about bikes

[WmY]

[Tamsin]

RE the LED headlight on the CG125, it can be an absolute SOD to get working correctly, I don't know if you are on FB but "CG125 UK owners" on there (disclaimer: my group) has a guy called Ben Wilson who has done the conversion and is happy to talk about it

[BusterGonads]

[WmY]