From: xrogers (xrogers@attbi.com)
Date: 09/02/02-09:36:12 PM Z
Hello, all.
It has been pointed out to me that I never posted the resolution of a
problem I was having with long printing times. Stupid me---mea culpa.
Here's a quick summary of the problem again.
> I'm trying out platinum/palladium printing. My exposure times to get two
> steps of maximum black on a Stouffer step wedge are more than 30 minutes,
> and I'm doing about 20 minute exposures for negatives.
>
> I'm using a home-built light box with 8 Sylvania F20T12BL tubes (about 1/4"
> between tubes) and two UltraLux electronic ballasts. My printing frame puts
> the paper about two inches from the tubes. I took the basic design from the
> Edward's Engineering web site (which claims the box should expose pt/pd in
> about 5 minutes), and got pointers to the ballasts from Sandy King's
> excellent UV light source article.
The problem turned out to be the UltraLux ballasts. The ballasts were wired
in parallel, one ballast to four tubes. Two of my three ballasts failed
after no more than two or three hours of use. I checked their light output
with a spot meter right after finishing the light unit. Twelve nice, even
tubes. Long exposure times, however. I fought with things for a while, and
then posted to the list. Dropping the contrast agent from the oxalate
helped some, but the times were still too darn long. Then, when exposing
another test, the unit gave a pop, and the display on my MetroLux timer
scrambled. Fortunately, the timer was okay after a power cycle, but when I
looked at the light, only one bank of tubes was lit. I checked the
(trivial) wiring, and it was fine. I swapped the ballast from the working
bank into each other bank, and they all worked fine.
I talked to UltraLux. They initially balked at helping me, claiming a
"non-standard" use of the ballast (that their salesperson had said would be
fine). Eventually, they agreed to check the ballasts and refund their
purchase price if they were defective.
The folks at UltraLux did refund the purchase price of the ballasts. They
did not provide specific information about why the ballasts failed, and
chose to refund my money rather than send new ballasts (or leave me hanging,
which I appreciate, although I wish the ballasts had worked, or that they'd
tried to help me get them to work). I wonder if the ballasts draw power as
indicated. I wonder if the ballasts interact poorly with other electronics
on the line. Or perhaps they just have inadequate quality control. Or
maybe I have spikey power. Or maybe I was just unlucky.
I didn't want to risk my favorite enlarger timer anymore, so I switched over
to the lower power magnetic ballasts suggested in the Edward's article, and
exposure times became far more reasonable (about 7 or 8 minutes). Things
run rock solid, my timer is happy, and I've exposed several dozen sheets
successfully (then summer came, and printing stopped until the snow flies
again).
If folks on the list have had good luck with these ballasts, they may want
to post something positive about them. My experience says to avoid them.
Thanks for the help,
--clyde rogers
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