Hey Monica - good to hear from you!
I'd keep the the 4-channel system (and so trade in the 3 channel item for the 4 -the vendor should be willing to do that). As for the PTS that is "wildly oscillating", my guess is that this is pretty easy to fix (there are some electrolytic capacitors in the power circuit inside the PTS that need to be dealt with). Indeed, there was recently some chatter here about this and so assuming I'm correct then you can direct yourself, or your electronics guru (is there still someone in Chemistry ?) toward repairing this for a couple hundred dollars or less.
I recall, too, that Barbara had problems with the shim power supply on that beast. Assuming they are the same console / instrument since she left (and they shut that program down over in Medicine) then be sure this is working okay. Agilent's latest software (VJ 4.2) works with the Inova and is well worth the upgrade since it has some nice tools for checking these kinds of problems out.
Why four channels - you just never know . . .
CD Rithner
Director of CIF, Sr. Res. Sc. / Sch., Chemistry Department, CSU, Fort Collins, CO 80523-1872, ph. 970-491-6475, mobile 970-391-9971, cdr_at_colostate.edu,
http://cif.colostate.edu
On Jul 9, 2014, at 2:23 PM, Monika Ivancic <mivanci1_at_uvm.edu> wrote:
>
> Dear fellow NMR gurus,
>
> I would like to solicit your opinion and/or advice on the following. An issue has come up on my 1995 genre Varian Inova 500 spectrometer, and I need to decide whether or not to convert it to a 3-channel system (from a 4-channel system) and if so, things to watch out for in the process.
>
> In my efforts to identify a "power drain" in my system, with help from a colleague, I found that the 4-channel N-channel attenuator (NCA) has one of its components (a 1 or 2dB attenuator) stuck in the 'on' position. Thus I ordered a replacement NCA thru a 3rd party vendor. Inadvertently, a 3-channel NCA was sent to me, and I did not realize the difference until I took my 4-channel NCA out of the system. I decided to go ahead and install the 3-channel NCA, to see if it would resolve the power drain, which indeed it did.
>
> However, my system is configured for a 4-channel system. It has 4 frequency synthesizers, two PTS 620s and two PTS 320s, and 4 transmitters, etc. Granted that the 4th channel likely has never been used, and is definitely not needed by any of the current users. It is a bit curious why a '95 500MHz system would have 4 channels in the first place, though likely back then this was cutting edge technology. Also, one of the PTS 320s is not functioning properly and when I measure the Voltage coming out, it is wildly oscillating.
>
> So, shall I officially change this system into a 3-channel system? Get rid of the PTS 320 that isn't functioning properly anyway? This would simplify some of the electronics. Although some questions come into mind, such as what to do with the 4-way splitter (terminate one out or get a 3-way splitter), then also what to do with the PTS bus cable connector?
>
> Have any of you done this with your system and if so, is there any advice you have? Another option would be to get the proper 4-channel NCA and leave the system as is, because... "why fix something that ain't broken".
>
> Your 2 cents on this one would be appreciated.
>
> Cheers,
>
> Monika
>
> --
> Monika Ivancic, PhD
> NMR Facility Manager (A-212)
> Department of Chemistry
> 82 University Pl.
> University of Vermont
> Burlington, VT 05405
> (802) 656-0285 office
> (802) 656-0279 NMR lab
> Monika.Ivancic_at_uvm.edu
>
Received on Thu Jul 10 2014 - 10:04:18 MST