jp
8-Feb-2010, 20:29
I have dichro dg color head on my cb7 4x5 enlarger. I took it off the enlarger to change the bulbs (which are cheap with the advent of the Internet). I took it out of the darkroom for this process.
The knobs were very stiff, so I set about investigating that. Getting the thing apart is pretty easy. Just loosen the set screws on the three dials, remove 3 screws from the faceplate, and it's open. Inside is a maze of wires on pulleys, like in an old AM pushbutton car radio. Lots of places for friction and gumming up. I gave the pulleys, bushings, sliding rods a few careful squirts of mass air sensor cleaner (cleaning solvent for electronics). Then I carefully gave those same spots careful squirts of silicon lubricant (being careful to avoid the dichro glass filters). Use the red tube that comes with the spray can when applying both liquids.
Put it back together, put in the new bulbs, make sure it's clean, put it back on the enlarger. The knobs spin a whole lot easier now. The resistance is probably like they should have; enough to keep the settings and enough to feel rugged.
The knobs were very stiff, so I set about investigating that. Getting the thing apart is pretty easy. Just loosen the set screws on the three dials, remove 3 screws from the faceplate, and it's open. Inside is a maze of wires on pulleys, like in an old AM pushbutton car radio. Lots of places for friction and gumming up. I gave the pulleys, bushings, sliding rods a few careful squirts of mass air sensor cleaner (cleaning solvent for electronics). Then I carefully gave those same spots careful squirts of silicon lubricant (being careful to avoid the dichro glass filters). Use the red tube that comes with the spray can when applying both liquids.
Put it back together, put in the new bulbs, make sure it's clean, put it back on the enlarger. The knobs spin a whole lot easier now. The resistance is probably like they should have; enough to keep the settings and enough to feel rugged.