Bulb from enlarger reflecting off paper

I print with a Durst CLS 501 enlarger and lately the circular shape of the bulb(Colamp 250s)(24v250w) is printing onto the paper. The bulb is like a projector bulb and it's the cone shape that is printing onto my paper. This happens if I am making a 6x6 or a 12x12.

I'm wondering if it's the last life surge of the bulb or something more serious. I haven't had it long enough to go through a lot of bulb replacements, but long enough to know that this is a new problem.

Any clues would be helpful. I do have a new bulb in my B&H shopping cart but wanted to hear from some pros before I buy something I can wait on.

thanks,

jb

You have the condensers in the wrong position, or the wrong condensers, for the focal length of the lens.

If there's condensers then it's the wrong light source, this is a diffusion head, with a light mixing box.

Sometimes the silver reflector material on the cone deteriorates, I've had it happen with similar bulbs used for display purposes.

Ian

I'll check the cone for deterioration and go ahead and order a new bulb, can't hurt. Thanks for the information!

jb

Hmmm...very odd. Did one of your diffuse plates fall out when changing mixing boxes or something?

That's a good idea. I'll check tonight.