Re: current readback

[Steven Clayton <smclayto@npl.uiuc.edu>]

It could also be an ODB corruption.  You could try removing all of
the .*.SHM files and reloading, for example, Nov16_odb_backup.odb
(if that's a good one).

Steven

On Mon, Dec 12, 2005 at 11:50:42AM -0600, Brendan Kiburg wrote:
> Hi Peter,
>   I'm not sure how to proceed with getting the mscb working again, but you
> can always turn the knob on the bertan manually up to whatever voltage the
> chamber is really at and switch the toggle on the back from remote to
> local.  Then you should be able to ramp the chamber down manually.  With
> all chambers down you can try restarting the mscb program (as root).
> 
>   I'm pretty sure steve said that you should be able to stop and start the
> mscb program without tripping the chambers, but the two times that I tried
> to do this, we received hard trips.  If the chambers will be off for a
> while (at least as long as it takes for the tpc to come back up), I dont
> think there should be a problem ramping them down as a precaution before
> restarting the mscb program.
> 
>   By the way, I was looking at the tpc current readback and noticed that a
> few attempts to increase the voltage drew a lot of current.  Are there
> serious problems or do we just not know yet?
> 
> I will be around for a little bit and then have a lunch
> appointment.  Please let me know if I can assist you further.
> 
> Best regards,
> 
> Brendan
> 
> On Mon, 12 Dec 2005, Peter Winter wrote:
> 
> > Hi Brendan,
> > 
> > in the meantime we found the detailed description in order to restart 
> > the frontends etc. I found it in my logbook and we performed all steps. 
> > Therefore, the readback problem is solved. At the moment it seems that 
> > we have a problem with the MSCB bus. We changed the voltage on muPC1 to 
> > 2450V but the current readback doesn't change. Also we reset the BERTAN 
> > for the TPC but we still receive the message that the HV tripped. 
> > Therefore, we concluded that somehow the MSCB communication is broken. 
> > At the moment, I discuss with Malte how to proceed:
> > 
> > - can we switch off and on the MSCB crate without tripping the chambers?
> > - maybe we can first switch the BERTANs to local but then we have to set 
> > them to the proper voltages since the ePCs and the muPC are still on voltage
> > 
> > We also tried to contact Steven (that's why I include him now to this 
> > email) and hope he'll might have some input to us because he might know 
> > best about it. It's tricky because we cannot ramp down the chambers now.
> > Peter
> >