I believe there is a similar jumper for lock board on all Varian consoles.
Ron
On 7/6/2015 12:11 PM, Plant,Daniel wrote:
>
> Hi Neil,
>
> I’ve seen this symptom in the past when the Z0 polarity is wrong.
>
> On the old GE systems, there was a jumper inside the lock module.
>
> On a Bruker with a BSMS, the jumper is on the adaptor plate to the shims.
>
> If nothing has changed on your system since it worked before, maybe a
> software setting got reset?
>
> The varian folks might have some insight on this…
>
> Dan
>
> *From:* Jacobsen, Neil E - (neil) [mailto:neil_at_email.arizona.edu]
> *Sent:* Monday, July 06, 2015 12:50 PM
> *To:* ammrl_at_ammrl.org
> *Cc:* Bao, Kevin - (kbao)
> *Subject:* AMMRL: Negative lock level on Varian Mercury-400
>
> I sent a query a while ago about pumping the vacuum space of a donated
> Mercury-400. We are now at field and everything works fine EXCEPT:
>
> The deuterium lock will lock in perfectly with lockphase set to 0 or
> 360, but the lock signal is negative. The display goes down rather
> than up when it locks. The field is stable and you can do long
> acquisitions. If I set the lock phase to 180, it doesn’t lock and the
> lock frequency drifts away from zero frequency.
>
> The problem is that you can’t shim on the lock signal. The shim
> display (red thermometer) shows zero lock level because it can’t
> display the negative lock signal.
>
> I’ve tried many combinations of rebooting the host computer,
> restarting the acquisitons computer, power cycling the console, etc.
> I considered the possibility that I’m locked on a 2H sideband, but I
> get a 1H spectrum centered in the spectral window normally using the
> standard parameters and tof=0, and I can’t find any other 2H signal in
> the complete range of Z0 (-2048 to 2048).
>
> I have to assume that some component in the lock system has gone bad
> during the long (4 year) sleep of the console, but I keep wondering
> (since it’s a Varian) if it might be a software issue. I would
> appreciate any suggestions.
>
> Neil
>
Received on Tue Jul 07 2015 - 18:43:21 MST