Futurelight MH 640 lamp always dies

[Theatermeister]

Hello, I have a futurelight MH 640 in which always the lamp breaks after about half a year. the bulb always looks a little blackened, what could it be? Ignitor or ballast?

greeting

[Brian]

Taps on ballast set wrong?

Fan(s) not working properly?

[timmeh2]

Hi

 

Can you take a close up picture of the centre envelope. You can tell a lot by the condition of the electrodes; although as Brian says it will be one of two things; overheating or overcurrent.

 

All the best

Timmeh

[Theatermeister]

The fans are working properly. Here is a pair of photos of the second bulb gone broke.

 

[gyro_gearloose]

The pins look fine, so its not a lamp holder problem. The outer envelope looks reflective, which could indicate mercury vapour has condensed on the inside of the outer envelope. This is a bad thing as there shouldn't be anything in the outer envelope. I'm not sure what has caused your lamp to do this, but there might have been a leak from the inner envelope into the outer one.

[KevinE]

could be a loom problem. If the mains feed to the head is allowed to make and break intermittently it can soon polish a lamp off

[timmeh2]

Hi

 

Silvering is usually down to excessive strike or drive voltage.

 

If you've got access to a mulimeter and are confident to stick your probes in the thing whilst it's running, read the voltage across the lamp once its struck. It should stabilise at around 60v DC, dropping rapidly as the lamp heats up. Anything else and you have a ballast fault.

 

That said, magnetic ballasts are usually highly reliable.

 

I'd also be tempted to change the ignitor as a precaution.

 

All the best

Timmeh

[Brian]

The OP hasn't yet confirmed if the taps are set correctly on the ballast.