Dear all,

We have a GC-MS model DSQII form Thermo since 2009, and now we encountered several problems as follows:
1- We replaced the GC coulmn with an new one (including the septum and liner).
2- We make the cleaning processes of all the components of DSQII as described in the manual.
3- The background spectrum (10 to 650) is Ok.
4- The air/water spectrum (10 to 90) is Ok.
5- All the diagnostics tests are Ok.
6- DC/RF value is 0.965 and detector gain is 3e5.
7- The background spectrum (50 to 650) is a little bit noisy and unstable (please see the attached video).
8- The peaks of the calibration gas at 414 and 502 are not observed clearly.
9- We make the autotune and we got a passed results.
10- We tried to repeat the aututune but we got a message (can not perform detector gain calibration).
11- We had a passed results of autotune when we decrease the DC/RF value to 0.960, but we still have the error message if we repeat the autotune again.
12- We noticed that when we increase the DC/RF value only a 0.05 unit, we got a too noisy calibration gas spectrum.
13- We noticed that the actual point of the RF dip calibration (after the autotune) is 1094.1 more than the set point in 1.9 KHz.
14- We noticed that both the detected RF and RF Mod in the RF gain calibration (after the autotune) are out of 1050 .

Please give us the possible causes and the suitable solutions in order to solve our problems.
Awaiting your advise.
Best regards