[pure-silver] Re: ELC bulbs failing in D2 Dichro Head
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 16 Jan 2008 07:36:37 -0800
----- Original Message -----
From: "Georges Giralt" <georges.giralt@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, January 16, 2008 2:56 AM
Subject: [pure-silver] Re: ELC bulbs failing in D2 Dichro
Head
Selon J Stewart <jrstewart8@xxxxxxxxxxx>:
Folks, can anyone help me troubleshoot reasons why my
lamps are blowing out
within a few seconds of turning on my Dichro II color
head (on a D2). I'm
using the standard D2 power supply with stabilizer. The
stabilizer fuse is
intact. The power cord is plugged into a surge protector
via the timer. My
house has always had a stable power supply.
The bulb elements are breaking. The problem began
immediately. A bulb I had
been using for a couple years fractured. When I put a new
one in, it burned
out within seconds. I repeated this with a new bulb and
the same thing
happened. One bulb actually broke the reflector in the
process, but I'm not
sure it was caused by the same problem.
I have a voltmeter to check current to the socket if you
can help me
understand what I might be looking for in isolating the
cause.
Thanks in advance.
Jim
Hi Jim !
If IRC the ELC is 24 V. As the power supply is stabilized,
it could be that it
went south and deliver way above the 24 volts needed. This
is easy to check, and
will not need a bulb.
Put the leads of the tester into the lamp socket and turn
the enlarger on.
You will get either 0 V (if the stabilized output stage
use the bulb as a
polarizing device) or a voltage. If it is above 24 V
you've got the culprit. Be
sure to check with DC and AC voltages (you may have an AC
voltage mixed with the
DC output, the sum of the two being above the 24 V).
If this gives you hte impression that the power suply
works fine, check for the
bulb base. These sockets use small diameter pins and
oxydize quickly causing
spikes and sometimes sparks.
Sometimes this make the lamp burn. Change for a high
fgrade one (go to the
lighting store the biggest you can find in your town) and
plan to change this
socket once in a while..;
Hope this will help !
--
In general I agree with this. I don't know what sort of
regulator is used in these power supplies but it sounds like
the regulation element has shorted or opened (which depends
on whether it is in series or parallel with the lamp)
causing the voltage to become very high. A clue is whether
the bulb flashes as it burns out. A voltmeter will tell you
what the open circuit voltage at the socket is. It should be
very close to the lamp voltage. It may be somewhat higher if
the regulator requires a minimum load (the lamp) to
regulate.
If the voltage is very high you will need to find the
circuit diagram to determine what the regulating element is.
Since lamps are failing instantaneously its unlikely
that its the socket or the lamp pins, the lamps are just
being blown out by high voltage.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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