Chromatography Forum

My Finnigan Magnum is giving me some headaches:

- The pre-owner changed the fans of the spectrometer. Alas it seems like the orientation of the fans is wrong. How is the correct orientation of the fans?
- Manifold temperature can be set to 350°C but the manifold only reaches around 210°C. What could be wrong?
- The unregulated +40V power supply is at 39,22 V while the spectrometer is cold and idle. When the spectrometer is at operating temperature the +40V source partially drops to +38V (it is rapidly swinging from +39,22 to +38V).
After switching on the RF it stays at 36 V. Could a defect of C2 on the power supply board be the cause?
- The spectrometer shows extreme ion current changes (around 30 percent). As the amplifiers and RF are fed from the +40V rail the cause is probably the swinging on that rail. Did you ever experience something like that?

Thanks!

So I'm answering my own topic

- The fans have to blow inside the spectrometer, i.e. getting fresh air into the system. Otherwise the turbo pump will overheat.
- The manifold is cooled by a stream of air so 220°C are the normal maximum temperature which is reasonable as contaminants will evaporate at 220°C and <10^-5 Pa.
- The voltage drops are the result of other loads on the same rail: The Magnum has a special dislike for inductive loads like pump motors and non-steady loads like a GC. Therefore the MS should get it's on rail
- The ion current changes were due to a leak in the CI system.