De Vere 5x7 Dichro head on a 504 chassis?

[JW Dewdney]

Hi - I just acquired (okay, well - bought) a DeVere 5x7 head on ebay for transplant onto my 504 chassis. From what I hear, it's pretty much a direct fit. However - one issue of concern is the power supply. It's a 500W head - and my poor little TranStab is set up for 250W. Clearly - one obvious (albeit expensive) approach to this would be to buy a 500W TranStab. However - I'm thinking that there might be a far easier and cheaper approach - which would be to use bulbs rated for half the wattage and all the same wiring? Are there any DeVere gurus out there who might be able to comment on this approach - or give me others to play with?

Thanks much
Jonathan

[Arthur Nichols]

Hi,
I have a Devere 5x7 enlarger and I love it, it is great enlarger. I recently burnt out my 500 watt Trans Stab. These things are very expensive to either repair or replace. I gutted the power supply and rewired the enlarger to use 2 250 Watt 120 Volt bulbs instead of the 2 250 Watt 24 Volt bulbs in series. I have not printed with it yet, but I have tested it and it seems to work. The Tans Stab is nice because of the regulated power supply, but I just don'g need that kind of repeatability. It all pretty basic wiring, but if you are unfamilair with electrics, some knowledable help would be a good idea.
All that being said, Glen Evans at Glenview has a power supply for an 8x10 head. Chances are that it would work with the 5x7 with some minor modifications.

[ppisczak]

Jonathan

Arthur has it exactly right if you wish to use two bulbs. But if your intention is to use one 250W bulb, then everything is fine the way it is, just that your exposure time should approximately double.

I've sometimes wondered if the best thing for an enlarger bulb was to run it on DC rather than AC. Edison did it, and because the bulb filament did not resonate at 60 hz, they lasted longer, sometimes decades. Also, one can get much finer light control with DC. Just thinking out loud.

PJ

[JW Dewdney]

I believe they ARE run off DC. Most enlarger bulbs (halogen) that I know of are. Hence the power supply. I'm guessing that what I'd need to actually do - is run 2- 125W / 12V bulbs in series - though I doubt they'd be wired in series. IF it's a 24v power supply - then it'd be 2x 125W 24v bulbs I'd need. There are TONS of halogen bulbs of the same format out there - very cheaply had, too.