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UV Light Box Died
Last night, it was time to start printing for the alternate process print exchange. Poured the chemicals, humidified the paper I coated Sunday night, heated the developer, even had the vacuum frame pulling 25" of Hg.
I turned on the UV light box, the fan went on, the bulbs didn't light up. The UV unit was purchased from the Palladio Company about 1991. (Boy, things just don't last the way they used to.)
The things I said made the picture of my wife's grandfather blush (and he was a sailor!).
Any suggestions on how to determine which (or all) of the ballasts need to be replaced? I have included a photograph of the wiring and a close up of a ballast.
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If none of the bulbs/tubes(?) light then it is not likely to be a ballast at fault and it is highly unlikely that all four would fail at the same time. It looks like you have four identical circuits wired in parallel so if they don't work, it will be something more fundemental such as no power getting to the ballasts.
If you have a multi-meter you could check for voltage at the ballast terminals.
EDIT: I would check for voltage at the junction of the four sets of black and white cables which (from your pictures) look like the power connections. They disappear off of the bottom of the picture but I imagine that all four blacks are joined and all four whites are joined and this pair is the voltage in.
Steve.
Last edited by Steve Smith; 10-10-2006 at 05:50 AM. Click to view previous post history.
Reason: More info.
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Also, are you sure there's power at your AC outlet? Seems basic but I've looked for circuit problems that turned out to be a blown breaker. Also, is the light unit fused? Is the fuse good? I agree with Steve that it sounds like something other than a bad ballast.
juan
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The fan works, the bulbs don't light up, so there is power getting into the unit. I have a circuit tester, but no multi-meter. If memory serves me well, I do believe Steve's guess on the wiring connections are correct.
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 Originally Posted by Joe Lipka
The fan works, the bulbs don't light up, so there is power getting into the unit. I have a circuit tester, but no multi-meter. If memory serves me well, I do believe Steve's guess on the wiring connections are correct.
There may be separate fuses for the fan and lights inside the box. Also check the connections between the switch and the lights - one may have come loose.
Good luck, Bob.
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Joe,
It is probably a wiring fault or a fuse. Go to the junction of the black wires and check the junction. Pull the wire nut and redo if it doesn't look solid. Do the same for the white wire junction. (WITH THE UNIT UNPLUGGED, PLEASE)
Before you do that, look for an in-line fuse in the wiring that connects to the ballasts, probably on the black line. The often look like a piece of plastic about the thickness of a pen or marker and about 2 inches long. It should be possibe to unscrew the connector and check the fuse. There may be one on both black and white wires.
Look for a fuse that is accessible from a cap on the outside of the unit as well. There may be two of them, one for the whole unit, and one for just the ballasts.
Without a multimeter, it's a bit hard to go through the circuiting without a bit of trial and error, but that may be how you will have to do it.
Steve is correct, the lamps will be wired in parallel.
Do you really use 25" of hg? I never use more than about 5". I figure there's no need to squeeze harder than is necessary to produce good contact. Less likely to damage the negative.
---Michael
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If you don't have a meter to check with, you could connect a lamp holder with a low wattage bulb fitted to the black and white wires to see if you have power at that point.
Obviously, I don't know your level of confidence/competance when dealing with electrics so if you are not sure about this, the answer is to not do it and get it checked professionally.
Steve.
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are the bulbs wired in a series?
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Originally Posted by Michael Mutmansky
Joe,
Do you really use 25" of hg? I never use more than about 5". I figure there's no need to squeeze harder than is necessary to produce good contact. Less likely to damage the negative.
---Michael
Yes, I do pull it to 25" of Hg. There is anecdotal evidence to suggest higher vacuum increases separation of the high values. PM me if you would like to discuss this obscure observation in more detail.
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Originally Posted by Joe Lipka
Yes, I do pull it to 25" of Hg. There is anecdotal evidence to suggest higher vacuum increases separation of the high values. PM me if you would like to discuss this obscure observation in more detail.
I also suspect the problem is an blown in-line filter. That would certainly be the best solution.
If you have any real evidence that shows an increase of separation of the high values with high vacuum pressure I would be very interested in seeing it. My experience is that more than 5-10 inches of mercury is plenty, and that more pressure can be detrimental in some cases. However, I am open to modify my thinking on this if there is evidence to the contrary.
Sandy
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