Chromatography Forum

We have been using a Varian Saturn 2200 MS for the past 9 years without any particular problems (other than turbopump replacement). Recently an error has been cropping up and is preventing us from using the MS.

Under diagnostics we are getting an error, under RF test:
The RF DAC failed at DAC 56. Likely causes include: The Rf Generator board is defective (RF DAC instrumentation AMP.)

Sometimes it is DAC 57 or 59, but usually 56.

(Filament 2 is also reported as OPEN even if this has never been used - I don't know if it is related to the RF error).

This started to appear after we were getting errors during a runs, (we do not run diagnostics regularly). The run starts normally with filament 1 off but when the filament should be turned on an error occurs:
Module 2000:40 : Error downloading scan function (1900906)

This was a minor occurrence but now it is very common and it has now become so common that it is no longer possible to do any analysis. At this point we ran diagnostics and got the error, though it may not be related.

The problem is that we no longer have any support and am hoping that it may be something that can be done by an experienced user. Anyone had similar problems?

Hi, you have two separate problems: about scan data error often is a pc communicatin problem. Try to verify your pc, especially if it is old and eventually disable antivirus and all programs running in background that slow the machine. If you can, add RAM to pc.
About RF, this may be related to simple adjustment: go to 2000.40 sw tile, then RF adjust e look the diagram. It must be a continuos "line" starting from left going to higher value on right. If you see any big step or interrution you must adjust RF using a big teflon screw in front of instrument (you must open front panel)
Try to reach the most lower reading on "HIGHEST" value, but if RF response is ok now your ms might work fine.
Good luck

Thank you Daniele for your reply.

I found out that I had 2 problems last week but did not update this post.

The filaments were changed and the RF DAC problems was sorted out by changing slightly R20 & then R66 to correct integration problems. Now a diagnostic 'System test' gives a 'Passed'. RF calibration was then carried out and as you suggested the teflon screw adjusted to get the lowest slope (about 800).

The PC communication is unfortunately not solved. There is no other software on the PC (no antivirus, no internet, no third party software other than the originally installed software). The PC is old with only 1Gb RAM so I will try to upgrade that, but HDD space is still >120Gb and no defragmentation needed (according to windows). What I have done is a 'repair' & validation of the Varian software, 'repair' of the windows software. The problem is still there and now it appears even when doing the FC-43 calibration. It is also stopping frequently during a run and it stops just when data collection should start. I am beginning to suspect it is a problem with one of the electronic boards which needs replacing.

Thanks again for your feedback.