Hi Isogeochemers,
After troubleshooting for a bit, I think
my original diagnosis was incorrect. It turns out that the pump HV source
light kicks back on when I closed the GCC valve, but didn’t go out when I
opened the Conflo valve – just normal vacuum. I tried switching the
capillaries between the different valves and when they were switched, the
results were switched – improper vacuum on what was the Conflo valve (but
now had GCC capillaries going into it) and normal (2.2 x10^-7) on what was the GCCIII
valve (now with the conflo capillaries going into it).
So there is clearly something wrong –
probably a leak – with my system upstream of the capillary/SGE valve
interface. I tried clipping about 3 cm of capillaries off of the inlet,
in the hopes that I had some kind of small crack right by the inlet nut on the
capillaries, but that didn’t do anything. At this point, I’m
not quite sure how to approach this. My gut reaction would be to tear out
the capillary coming from the GCCIII interface and replumb it into the source,
but this seems a bit extreme.
Any thoughts?
Thanks again,
Mike Kubo
From:
Sent: Wednesday, July 29, 2009
1:23 PM
To: [log in to unmask]
Subject: [ISOGEOCHEM] Source HV
Down on a ThermoFinnigan Delta Plus XL
Hello Everyone,
Of course, just before I’m about to run a 1 shot
meteorite sample, our HV just went down. Here is the play by play:
1) Had been
running EA, so before I opened the GC-C-III SGE valve, I turned off the
filament HV button the front panel so as not to flood the source with gas and
trip the HV.
2) Came back around
to the front side of the instrument panel to turn the source HV back on.
Depressed button, only to see that neither the source HV light or the emission
light came on, but the red LED on the button did. In addition, the source
HV light on the pump LED panel was also off. Source vacuum indicates 3.3
X 10^-5 – clearly not the vacuum of 10^-6/10^-7 I typically operate at.
3) If I try
power cycling the “pump” switch on the front of the instrument, the
pump source HV LED will flash twice, then stay out.
So my guess is that I have a bad source turbo and the source
HV won’t kick on because of this. If anyone out there has other
ideas that don’t involve weeks of downtime and several (tens of)
thousands of dollars to repair, PLEASE shoot me an email! Your help is
greatly appreciated (as always) and a lonely chunk of meteorite will be very
grateful as well.
Cheers,
Mike Kubo
****************************************************************************************************************************************
Michael D. Kubo
M/S 239-4
Bldg. N239, Room 327
(650) 604-6110