From: ken watson (watsok@frii.com)
Date: 06/20/01-09:09:48 AM Z
I have read somewhere.....
That for some fixtures it is important to have a "grounded" fixture or piece
of metal close to a few types of fluorescent lights to get them to light.
It also occurs to me that since "Ballast's" ,also known as transformers or
inductors are involved, it could be there is interaction among or between
them.
Simple things to do:
reverse end to end the offending fixture. If there is interaction with the
ballast's causing this fixture to not operate reliably doing this will tell.
Unless it is exactly in the center of the fixture. From and electrical
point of view these things generate a magnetic field. If two of these are
placed so that their fields are opposite, they cancel each other out. In a
bank there may be enough canceling from two ( one on each side ) to cause a
middle one to fail. This is remote though.
These bulbs are temperature sensitive initially. So let them warm up first /
for a while and see if the offender eventually stabilizes. Once warm then
you can place you work under it and restart. It should continue to work as
long as it stays "warm."
With respect to "grounded" fixtures. If you can ground aluminum foil had
have it in close proximity of the bulb and this cures the problem, then THAT
was your problem. Make sure your fixtures are all grounded.
One could have bad bulbs or bad "ballast". These come in various quality
levels. IF you have fixtures made by Lights of America, from personal
experience, you have the cheapest ballast there is on the planet, as for
quality...you can guess.
I have had the same experience Judy has mentioned that buying ballast and a
new fixture is almost a wash from a cost standpoint.
I use the same guide to quality for fixtures as I used to use for tape
drives. Weight. If it is heavy it is strongly constructed. Most of the
weight in a fixture will be the ballast. They are 95% Iron and copper The
more wire and the more iron the more power they can handle, the more they
weigh and the higher their shipping cost. SO to stay in business a
manufacture who wants to keep a quality name will add the extra material to
make sure everything will work even in marginal conditions. A manufacture
only concerned about cost minimizes everything.
The counter to this are electronic Ballast's . I have not run across any yet
but I do know "Light's of America" was looking at these to lower cost. I do
not know if they succeeded. BUT electronics fail, Iron and copper does not.
..-----Original Message-----
..From: Judy Seigel [mailto:jseigel@panix.com]
..Sent: Tuesday, June 19, 2001 8:50 PM
..To: alt-photo-process-l@skyway.usask.ca
..Subject: Re: Another Lighting Question
..
..
..
..
..On Tue, 19 Jun 2001, Jeffrey D. Mathias wrote:
..
..> Keith Gerling wrote:
..> > ... I have a self-constructed bank of BL
..> > bulbs that usually has a problem "coming alive". ...
..>
..> > ... a lit fixture can occasionally go dim in the middle of
..an exposure ...
..>
..> As Judy suggested, check the ballast. Definitely ballast or maybe lamp
..> if mid exposure.
..
..Judy said "starter," perhaps dating herself -- all my old fixtures have
..starters. I wouldn't know how to check ballast. Perhaps you can tell us.
..But replacing a ballast costs as much as replacing the fixture.
..
..When I had trouble similar to what Keith describes, it was either
..
..1. cured by new starter
..
..2. cured by more firmly seating the bulb (twirling the pins around until
..they sunk in)
..
..or
..
..3. one fixture refused to be cured. Wouldn't turn on at all except at odd
..moments. Finally trashed it.
..
..But Keith, was it you who said you had silver foil under the bulbs? If
..that's crinkly kitchen type foil, I'd bet the farm it's diffusing your
..image. Well, maybe not with a digital neg, but sure did with silver
..gelatin neg. Try a 21-step with and without -- you may be amazed. (This
..shows most clearly on smooth paper and cyano, pt/pd, or VDB.)
..
..Judy
..
This archive was generated by hypermail 2b30 : 07/12/01-11:41:54 AM Z CST