Help: Omega C760 Diffusion Enlarger

[DrZ]

My Omega C760 diffusion lamphouse burned 2 bulbs recently. The last one purchesed from Freestyle only blinked once and burned.
The enlarger is 110V and the internal circuit consists of one diode (R6055) and a 1 ohm resistor (VC5E). The diode-resistor reduces the voltage from 110 V to 82 V. The bulb is ESJ (82V, 85 W). The diode is in short circuit and the resistor is open.
I appreciate any help on replacement of the diode and resistor, or any other system to reduce the voltage to 82 V.
Beseler 23C uses the same bulb. Maybe the system used in Beseler to reduce the voltage from 110V to 82V will also work here.
Any help is appreciated.
Thanks,
DRZ

 

[Donald Miller]

I've got a C760 that I haven't used in years. Does yours use the external regulated power supply? Mine has a regulated power supply that is separate from the enlarger.

It sounds as if your power supply was not cutting power prior to it's failure. That would account for the short bulb life.

The use of a diode makes me think that what they had in mind originally was a half wave DC output of 82 volts. You should be able to pick up replacement componants if you want to repair this yourself.

In lieu of that perhaps the power supply could be picked up on Ebay. I think that overhead projectors would use a power supply that you require...albeit sometimes more robust then 85 watt.

 

[DrZ]

Donald, thanks for your reply. I don't have regulated power supply. You are right, probably the diode got in short and burned the bulbs. I could repair it if I knew which type of diode to use. Most probably the diode-resistor will reduce voltage to 82 V.
Regards, DRZ

 

[DrZ]

Just called Omega and got the information from Bob. The resistor is 1 ohm, 5% 5W wire wound. The diode is 600VAR 6AMP, Motorola catalog MR 756.
This could be of help for somebody else in the future.
Thanks,
DRZ