Headlights keep blowing
 

This one puzzles me. I have an idea what the issue is but am looking for clarification.

I keep blowing my headlights. When the headlight blows I am forced to use the main beam. It's not long when this blows as well. The sidelight bulb however never blows. When I say it blows, the elements are broken.

I originally thought it was the wiring block as I know there were dodgy connectors in there. But I have now withdrew the wires from the block and soldered the wires direct to each other, in effect I have by-passed the block.

I then wondered about vibration but this is not the cause. It started on my twin fighter lights (blowing both bulbs) and has carried on with the new headlight I have now. I know it is not the wiring as when changing from the old lights to the new, all the connections in the headlight have been done again. New solder, good connections and proper heat shrink wraps used.

As I said, I have an idea what the issue is but will wait to see if people back up my thoughts before stating what I think it is. I can do without those that second guess and jump on the bandwagon and agree with what someone else says just because that other person seems to know what he/she is talking about.

So after that, is there anyone out there going to step up and give a considered and knowledgeable suggestion ?

Re: Headlights keep blowing
 

My haynes manual for my SV suggests that constantly blowing bulbs are a sign of the regulator/rectifer beign faulty.

Have you had any blown fuses aswell?

Matt

Re: Headlights keep blowing
 

No other faults. No blown fuses, nothing. Just the headlights blowing.

Re: Headlights keep blowing
 

What's the DC output Mr Ape?

Re: Headlights keep blowing
 

Hmm...blown fuses would add strength to the argument that its a faulty regulator; don't go on my sugestion just yet then.

Matt

Re: Headlights keep blowing
 

Don't know. Something I intend to investigate at the weekend.

Re: Headlights keep blowing
 

Too much current through the bulbs will burn them out. Change the regulator. See the Haynes manual page 9.31 :)

Re: Headlights keep blowing
 

At the risk of "jumping on the bandwagon", I too would suspect the regulator if, as you say, the wiring is OK. I suspect over voltage (therefore driving too much current, which is a nightmare for filament bulbs) which is what the engine alternator will produce when run at speed, easily up to 15V+ unregulated.

Do you get the same problem if you leave the lights on without the motor running? If not, this would add weight to the over-voltage theory. If you've got time to recharge (as, unfortunately it will run the battery flat quite quickly), perhaps try it one evening or overnight to see how long they last.

Re: Headlights keep blowing
 

If it was a really serious voltage problem, then you'd expect other bulbs and/or fuses to blow, but it's possibly just a weird combination of the higher power headlight being just sensitive enough to react to the increased current caused by a small over-voltage.

Fuses are surprisingly tolerant to small overloads. The high beam may be robust enough to cope (being even higher wattage filaments) and the lower power tail light etc may have sufficiently higher resistance to survive for longer.

Sounds tenuous I know. As suggested previously by others, you really need a meter on the terminals to check the voltage.

Re: Headlights keep blowing
 

At the risk of sounding patronising/stupid, when installing the bulbs are you being careful not to actually touch the glass bulb? I only say as a friend of mine had the same problem, bulbs constantly blowing, and turns out he was always handling the blub and touching the glass... which of course gets grease on it causing hotspots.

Just my tuppence worth.