cooling fan on Durst 138?

[Liquid Artist]

I finally got my Durst 138 up and running, and what surprises me is the amount of heat coming from the bulb.

So I am wondering if a cooling fan would keep it cooler, and hopefully extend the life of the bulb.

What are your thoughts on it?

[Jason Greenberg Motamedi]

How many watts is the bulb? I run a 150 watt bulb in my 138S and it never seems to get very hot. The Durst manual I have calls for a fan at 300 watts.

[LabRat]

Depends...

Some enlargers like the Leitz V35 have NO cooling fan (and the lamp is enclosed in a thickish aluminum housing ,but with a heat sink/cooling fin arrangement) that keeps the lamp warm, and cooling slowly (to avoid thermal shock)... (These go through lamp sockets like crazy!!!) Or heads with a lot of plastics (nylon gears, plastic dials, wiring, etc) that need not letting heat build-up in them and NEED a fan... (And mechanicals that can bind up from heat expansion...)

I felt some color heads that you can cook an egg on... (Halogen bulbs get HOT!!!) But bulb life will be generally greater if the bulb is allowed to cool off gradually, so too much fan action can actually hurt the bulb from thermal shock... (But there's the bulb chamber, and the rest of the head...)

Steve K

[Liquid Artist]

Thank you for your replies,

I believe that it's still the factory bulb, so Durst must have thought that it's alright.
I wouldn't care as much if I could still get factory replacement bulbs.

[LabRat]

But on some later Durst's, I have seen where they put nylon parts very near the lamp assy., and the parts were brittle and breaking... (What were they not thinking!?!!!) Don't assume with Durst...

But survey inside the head to see how much plastic is around... (I think the earlier heads were mostly metal) If metal, then you can safely use most bulbs...
And if there is some bottom to top of head air/convection flow path, to allow convection cooling...

One upgrade to allow for better cooling is that any place that joins to the bulb chamber, (or any plates that get hotter than others), clean the seams where the plates join to bare metal, and get a good quality heat sink compound (from the electronics or computer store) and apply inside of the seams... This will keep the heat moving, instead of concentrating it in one area...


Steve K

[Liquid Artist]

Thank you once again Steve,
I will take a look tomorrow.
It's nice getting my darkroom finally up and running again,

[ic-racer]

Yes, you will want to us the LAFAN blower with lamps greater than 300 watts. Do you miss this in the manual?

[Liquid Artist]

What is a Manual ic-racer?
I thought that booklet was just there to throw in the recycling bin.
Since I got my enlarger third hand, someone beat me to it.

I actually remembered reading something in the downloaded version. However I basically look at such suggestions as guidelines. I have also come to realize that someone with experience using these enlargers may have different / better ideas through trial and error.

Besides the fact that Durst had no way of knowing the bulb production would halt before all their enlargers hit the scrap yard.

[ic-racer]

I thought that booklet was just there to throw in the recycling bin.

I suspect you are joking, however, I hope you realize specialized equipment like the Durst 138 can kill you in more than one way if you don't know what you are doing. The prudent operator will have the instruction manual memorized. If anything I'd be more careful with the equipment than the indicated recommendations, seeing as how the equipment is irreplaceable.

I can just imagine the news report..."Liquid Artist succumbed today to injuries sustained in a fire that started in his home darkroom yesterday. Apparently he had been operating vintage lab equipment outside of manufacturer's safe operating specifications based on advice he received on an internet forum..."

[Jac@stafford.net]

I wouldn't care as much if I could still get factory replacement bulbs.

Are you sure there are not equivalent bulbs? Pardon my ignorance.

For Edison type bulbs, I use ceramic sockets. Of course then the first thing to go is the wiring at the base.

Aside - a Leitz enlarger was mentioned - The early Valoy could be had with an extra cooling bonnet to allow 250W bulbs. I wish it worked on the IIA.

Right here on the bench I have a large lens cone (pyramid shape) that is a frame with two thin plates on each side, one inside, one outside. It permits ventilation without leaking light. I think its design was to allow atmospheric balance at altitude, but it serves another purpose, too.

Plastic gears are made to be broken, fried brittle. It might be worth perusing McMaster-Carr for metal replacements.

OP, is this the proper instruction book?

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