Agilent 5973 GCMS Source temperature keeps increasing

Thanks for the reply Dan!  I took the boards off and cleaned them (there was a lot of stuff on the backsides).  My source temp follows feedback.  When I adjust the setpoint it goes about 20C above then falls back down to the desired setpoint within 1.5 minutes.  Now when I adjust the quad temperature the source temp increases, is this thermal equlibration or still sounding like the board? Thanks

To be honest with you , I typically set the temperatures to 100C when I first pump down a system and then verify that I have good vacuum.  At that point I set the temperatuires to my operating setpoints and walk away, typically overnight.  The next day I check the temperatures and water content to make sure they are stable and good.  I really have never watched them while heating up.

If after overnight they are not stable, there is an issue that needs to be addressed.

Dan

Hi Dan,

thanks for your help!  I'm still chipping away at this issue. 

I'm able to maintain the source temp feedback and get it up to 230C and be stable.  Unfortuntly once the filiment turns on (for instance during tuning) the temp starts to increase.  Does this still sound like a board issue or is it more likely I still have temperature cross talk between components? 

Thanks for your help

Rory

Rory,

Does the temperature continnue to rise as long as the instrument is scanning?  Also what temperature is your MS transfer line at?  This is a bit odd and I want to make sure we are getting the correct answer to the issue.

Dan

Hi Dan,

When I have the ms quad temp set to 50C the source temp can be held at 230C.  If the quad temp setpoint is set to 60C the source will increase to just above 260C.  With the filiment on (during a tune) the source temp will increase over 400C, then come back down to 230C over the course of a few hours. 

Is the transfer line set using Aux 2?  if so I've slowly increased that to 280C over 3 days while keeping an eye on the source temp.  The source temp did not increase while adjusting Aux 2. 

Thanks

Rory,

This is not typical behavior and to track it down is going to take some work.  Yes the Aux 2 is typically the transfer line and unless you have a second auxillary heated zone (ie valve oven) it should be the only aux zone active.

It sounds like you have a short in the system somewhere or the electronics are malfunctioning.  I would be check the resistance of the source and quad heaters as well as the temp sensors.  I would also be checking to see if any of the heaters have a short to ground when installed.  If all resistances are within tolerances, and there are no shorts in the system, I would look at replacing the main board on the MS.

Dan

Thanks Dan, I checked all the resistances a while back (thats how I found the broken rtd sensor on the source).  I'll check if anything is shorted to ground and let you know.  Thanks again for the advice,

Rory

Hi Dan,

Thanks for your help, The main board needed to be replaced.  I was able to get the machine up and running over the holiday break!  Thanks

Rory