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Hi Andrew,
I can't speak to the reason "that the electrodes are not even visible" after 
so few hours, but that is likely the remains of the electrodes, not mercury. 
The "bubbles" you see in the newer bulb are probably droplets of mercury. 
This is a sign of a new bulb.  It is this metal that is vaporized  when the 
arc forms and produces the light.  There was a thread recently on this 
listserv that centered on whether one could replace the standard 102 bulb 
with a 103, and most folks said they had had good luck with it.  I think the 
implication was that some systems would not handle the 103 well, and yours 
may be one of them.  I agree with George, that a new lamp housing may do the 
trick.
Cheers,
Carl

Carl A. Boswell, Ph.D.
Molecular and Cellular Biology
University of Arizona
520-954-7053
FAX 520-621-3709
----- Original Message ----- 
From: "George McNamara" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, June 20, 2007 7:59 PM
Subject: Confocal Microscopy List <[log in to unmask]>


> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
> Hi Andrew,
>
> There is a famous quote, "never trust anyone over 40" or some such. to 
> which I will add: never trust a piece of equipment older than you, 
> especially if it can explode in your face. I see you are in a dept of 
> mechanical engineering, and that your lab is probably pretty confident of 
> your modifications. But, why take THIS risk? In particular, you mention 
> "bubbles inside the bulb". Sounds ominous. You had the money for a new 
> power supply - spend some more money to get a new lamp house, and put in a 
> brand new bulb.
>
> By coicidence, I just replaced an old Atto Arc power supply/lamp house 
> with a new Zeiss FluoArc, on our LSM 510 confocal (thanks to Zeiss and our 
> service contract). Both use the same Hg bulb you mentioned. The FluoArc is 
> very bright. Upshot: New is good. Of course I have no idea whether this 
> brightness is due to also having a new bulb (the last one exploded, and 
> took out the old lamphouse innards), or maybe Zeiss made a better 
> collector lens or other component. Might just be new wires beat old 
> corroded wires. I'm probably going to retire the Atto Arc on our other 
> Zeiss scope and buy a Fluo Arc for that scope.
>
>
> George
>
>
> ************************
> Hello Everyone,
>
>
>  This is my first email to this list. I apologize that this is not
> exactly related to microscopy, but this seems to be the largest
> knowledge base about mercury vapor lamps that I have been able to
> find on the internet.
>  We are using an HBO 103W bulb for our Schlieren imaging system for
> supersonic flow visualization. The old setup used an OSRAM 200W/2
> bulb with a lamp housing and lens (J. Unertl Optical Co.) and a
> power supply from Robert W. Gates & co.  The equipment must be at
> least 30 years old, if not 50 years. Recently the power supply
> stopped working, and we purchased a Nikon C-SHP1 power supply. We
> hooked up the power supply to the old housing
>
> (making certain modifications),
>
> and used an HBO103W bulb which worked fantastically
> for about 30 hours, having been turned off and on maybe 10 times.
> The last time I tried to light it, the "Lamp Ready" light flickered
> for 1 or 2 seconds and then went off. Examining the lamp, it did not
> explode, but the inside of the glass is covered with mercury, so
> that the electrodes are not even visible. I did not even try to
> relight the bulb, I just assumed it was ruined.
>
>
> I think that the bulb has probably failed from the modifications
> that we made to the connections in the housing. The first
> modification was that the mount for the bottom of the bulb had to
> be made smaller because of the smaller diameter of the 103Wbulb.
> This we did by using a small sleeve of copper inserted into
> whatever metal material the existing mount was, possibly bronze.
> After the bulb stopped working, the inside of the copper sleeve is
> tinged pink, compared to the outside.
>
>
> For the top bulb mount, the old style bulb we were using had a
> screw on it, and was attached to a flexible wire protected by
> ceramic beads. The new style does not have a screw, so we made
> another sleeve out of copper with a screw to tighten. The flexible
> wiring with ceramic is still used to account for thermal expansion.
> After running, the top copper mount is now dark gray-colored
> (probably oxide), but this can be scratched off.
>
>
> One other thing I noticed before the bulb would not light was that
> there appeared to be some small bubbles inside of the bulb near the
> bottom electrode after I had run it a few times.
>
>
> I appreciate people taking the time to help me on this, and I intend
> on attempting to contact OSRAM regarding this matter, but this
> seemed like a good place to look for assistance.
>
>
> Thanks,
> Andrew O'Grady
>
>
> -- 
> Andrew M. O'Grady
> 212-854-7306
> PhD Candidate
> Mechanical Engineering Department
> Columbia University
> Mudd Building
> 500 West 120th Street
> New York, NY 10027 USA