Hi folks
Had a strange one tonight switched on headlights and they blew instantly changed them and no more probs thought it was funny how they both went at once just wondered if this had happened to any one else

Trev

I had exactly the same with my series 111 except I was driving when mine blew
It was the regulator on the back of alternator that went on my car (200tdi 65amp retro fitted) causing 18-19 volts to run through the system thankfully the bulbs were the weak link and popped before any wiring damage
New regulator and brushes fitted for 20 quid and new bulbs all round problem solved

Hi
Thanks for that if alternator had failed would it not have blown the ones I put in after
Trev

tyrefitter said:

Hi
Thanks for that if alternator had failed would it not have blown the ones I put in after
Trev

Click to expand...

No not necessarily. Bulbs deteriorate over time. Newer bulbs will take a slightly higher current/voltage but will eventually burn out.

I would put a meter on the lamp plugs and see what voltage you are getting. If it's to high then there is a good chance the will blow as well and sods law says they will blow at worst possible time.

It sounds like you old bulbs acted like a fuse protecting the rest of the electric. New bulbs may not blow as easy and therefore the higher voltage may damage a more expensive peice further down the line.

Investigation needed me thinks

It's worth looking at some lower power bulbs too. If a low wattage bulb is supplied a higher voltage than its designed to take, the glass envelope begins to blacken. This blackening is caused by the overheated filament dispersing onto the glass.
This only happens on low wattage bulbs that are over driven for long periods of time.