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Robert,

Did you check the gap? Is it this gauge:

https://www.idealvac.com/files/cataloghelpfiles/Edwards%20Active%20Inverted%20Magnetron%20Gauge%20-%20Electrode%20Kit%20Instruction%20Manual%20D145_45_840.pdf

andy

On Fri, Sep 28, 2018 at 3:36 AM Geldern, Robert van <
[log in to unmask]> wrote:

> Hi Wolfram,
>
> it is going through an UPS unit.
> So I did not expect a problem here but I will see if I have the technical
> equipment and knowledge to check.
>
> regards,
> Robert
>
> > Am 28.09.2018 um 10:46 schrieb Wolfram Meier-Augenstein (pals) <
> [log in to unmask]>:
> >
> > Hi Robert,
> >
> > Have you checked the power supply to the lab / IRMS? Is it stable and
> within specs?
> >
> > Best,
> >
> > Wolfram
> >
> >
> > Prof. Dr W Meier-Augenstein, FRSC
> > Stable Isotope Forensics
> > Robert Gordon University Aberdeen
> >
> > Sent from my BlackBerry 10 smartphone.
> >  Original Message
> > From: Geldern, Robert van
> > Sent: Friday, 28 September 2018 08:27
> > To: [log in to unmask]
> > Reply To: Stable Isotope Geochemistry
> > Subject: [ISOGEOCHEM] Unstable vacuum readings and signal on a Delta V
> >
> >
> > Dear friends,
> >
> > after a week of struggling it is now time to ask four the wisdom of the
> community.
> >
> > I am in South East Asia trying to get a Delta V Advantage running. The
> main issue was originally a regularly oscillating (2 sec interval) high
> vacuum reading (fast changes between 5.8 and 7.9 x 10^-8) together with
> fluctuations of the box/trap ratio and signal intensity. All four
> oscillated together, visible as an up and down pattern in a time scan. For
> the signal intensity it seems that the amplitude of the intensity changes
> depended somehow on the m/z measured and were smaller for m18 (50mV)  but
> extreme für e.g. m28 (50V).
> >
> > With ion source off we did no see any noise anymore in the detector
> and/or the filament but the vacuum reading was still flickering.
> >
> > What we did so far:
> > - replaced the fore vacuum rotary pump
> > - cleaned all tubings from the fore pump to the turbo and removed all
> oil contamination
> > - changed the oil wick of the large turbo (small is not installed)
> > - checked ion source connections and changed filament, just in case
> > - removed the Penning gauge and cleaned the tube mechanically
> >
> > After re-assembling everything the instrument started smoothly within a
> couple of minutes. The turbo and fore vacuum sound is OK.
> >
> > However, vacuum readings are now far off and still flickering. Reading
> on Isodat is now 6 x 10^-10 and 2 x 10^-9. This is totally unrealistic and
> we do not get a green light on the vacuum LED on the front panel. Obviously
> Isodat also thinks that is out of range? I did not find a documentation
> about a lower end trip point, only about the upper set point (meaning when
> your vacuum is not good enough).
> >
> > We measured the Penning voltage and the trip point on the access points
> MP11/12/13 on the power distribution board of the Delta V. Voltage is
> between 2.1 and 2.2 Volt, which Isodat interprets as an extreme goor (or
> unrealistic?) vacuum. We are not able, of course, to switch on the ion
> source to see if we still have fluctuations on the signal. Wa also
> exchanged the cable between the Penning’s magnet housing and the board.
> >
> > From my current interpretation we might have 3 options:
> > - a broken Penning gauge
> > - a broken/not correctly working magnet housing
> > - a problem with the power supply or reading of the voltage on the Delta
> V board.
> >
> > What I would appreciate are thoughts about further tracing down the
> problem. Unfortunately we do not have a new Penning gauge or Magnet housing
> at hand. Any options to cheat on Isodat or how to check if board supplies
> the correct power to the Penning or to somehow calibrate the Penning?
> >
> > I also fully open to new suggestions regarding the original problem of
> fluctuations in vacuum-signal-filament readings.
> >
> > regards,
> > Robert
> >
> > --
> > PD Dr. Robert van Geldern
> > Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) | GeoZentrum
> Nordbayern
> > Schlossgarten 5 | 91054 Erlangen | Germany
> > [log in to unmask] | www.gzn.uni-erlangen.de
> >
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> --
> PD Dr. Robert van Geldern
> Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) | GeoZentrum
> Nordbayern
> Schlossgarten 5 | 91054 Erlangen | Germany
> [log in to unmask] | www.gzn.uni-erlangen.de
>


-- 
Andrew Schauer
206.543.6327
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*http://isolab.ess.washington.edu/ <http://isolab.ess.washington.edu/>*