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Electron Microprobe Lab, University of Minnesota
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Thanks for the input. As of now, here is where we stand...
-John ~~ There is no foreline trap. The pump itself can pull
appropriate vacuum. We tested it before installation by measuring it
while pumping on itself.
-Ritchie/Kevin/Ron ~~ I checked both thermocouples and both are
working. I have since bypassed the temperature switches so that the
system believes the DP is hot. 30 min timer still flipped.
-Clayton ~~ we have just recalibrated the pirani gauges. We will
probably end up cleaning them shortly.
-Steven ~~ We will certainly look for this. In fact, we found a leak
in a P10 tube and we replaced them all. Thanks for the suggestion
Thanks again all for your contributions. I'll update after some more pumping.
On Wed, Jul 6, 2011 at 4:09 AM, Steven Cogswell <[log in to unmask]> wrote:
> JEOL Probe Users Listserver
> Moderator: Ellery Frahm, [log in to unmask], Electron Microprobe Lab,
> University of Minnesota
> Post a message: send your message to [log in to unmask]
> Unsubscribe: send "SIGNOFF PROBEUSERS" to [log in to unmask]
> On-line help and FAQ: http://probelab.geo.umn.edu/listserver.html
> * Hi folks;
> I'll add my two cents on this topic. We recently had a problem with our 733
> that it wouldn't switch over to the diffusion pump within the 30-minute
> timespan when rough pumping, but would usually get it after restarting with
> the key. The problem actually turned out to be one of the thin-windows on
> the gas-flow spectrometer counters. Counter window had a defect was leaking
> just enough P10 into the chamber to make the vacuum poor. We replaced the
> counter with one with a good window and it went back to pumping down like a
> Easy way to check this is just to take the external hose off the outside of
> the spectrometer and bridge it with a small piece of hose. If it pumps down
> great that way, check your interior hoses/counter.
> I think our 733 gets from atmosphere to the diffusion pump switchover in
> nine minutes, and we get the ready light by about 15 minutes (6 minutes
> after switchover to diffusion pump). That's from memory so I might be off
> a bit.
> Best regards,
> Steven Cogswell, P.Eng.
> On Fri, Jul 1, 2011 at 12:49 PM, Anthony J. Ruth <[log in to unmask]> wrote:
>> The superprobe I am working on is having vacuum trouble. We need to run
>> roughing pump for an extended period of time to reach low vacuum and turn
>> on the
>> diffusion pump, but there is a timer that turns off the system if high
>> vacuum is
>> not reached in 30 minutes. How can I disable the timer? I have tried
>> the potentiometers on the manual pump control panel so that all three
>> meters report high vacuum, but it still did not disable the timer.