Hi there

How did you measure the 230 volts from the pins?

There's a few things you need to know about metal-halide lighting

1) They must have suitable control gear to operate, this comprises of a transformer, an ignitor, and a capacitor. They are not "ordinary" transformers.

2) The control gear "Ballast" must be situated at least half a meter away from the light so it does not overheat

3) The metal halide lamps get striked (pulsed) at 4-5kV (5000V), and then operate/run at around 100V

4) For standard metal-halide lamps (quartz), they must have the pointy bit on the inside of the lamp upwards

If the lights have never worked correctly then it sounds to me like you/they don't have the nessecary control-gear. If they have worked correctly before you either have a faulty or blown lamp, or if you've replaced that, turned off the supply, and it still doesnt work then you have a faulty transformer or ignitor, and the fitting or ballast needs to be repaired or replaced.

Your are correct in that it is important to replace lamps as they near the end of their life, if you don’t you risk damaging the fitting. Fittings will otherwise last many-years if looked after properly.

Word of advise, be very careful when servicing or repairing these type of lights if your not sure what your doing, with the high voltages present inside it's rather dangerous, and I don't want anyone killed on my watch!

You wont measure the strike voltage, all you ar seing is the open circuit voltage.

It is likely the ignitor that is gone, as the 'choke' usually fails by shorting out and blowing fuses, or atleast looking and smelling f'ed.

It is more often than not cheaper to get an entire new fitting.  Robus are  middle of the range, although there products in recent years have been becoming very good quality.  Their earlier stuff was tat.

Ok all Qu's answered now,thanks again.
Its reassuring to you know you can get A1 advice on here

I once watched someone set fire to a chep multimeter trying to measure the strike voltage on a 1200w HMI lamp