HED Fault

Hi  @Mg7, there are the possible causes:

 1)make sure the solvent delay is long enough 

2)  Vacuum is not good enough like the vacuum manifold pressure is too high

3) HED high voltage lead is shorted to ground. please check  the HED high voltage lead. Make sure it is connected and not shorted to a grounded surface.

4) the detector  is  contaminated, Cleaning the HED - 5973A/N (agilent.com)

5) MSD electronics, it could be a problem with hed, hed power suplly or main board

I appreciate your feedback,

Thanks

Does your MS have a turbomolecular or diffusion high vacuum pump?   Does your system have a high vacuum gauge?

How long has the system been pumping down before trying to tune?  It needs to pump at least an hour or more for good vacuum.

Verify that there is PFTBA in the vial and that the nut holding the vial and O ring is tight.  If that O ring leaks a big burst of air flows in and the system will shut down like this.

Try an STUNE, a standard spectrum autotune. That is a fast way to make sure it's not a bad tune file.

It has nothing to do with solvent delay. It has nothing to do with a contaminated detector as it does not even turn on. If you did not remove it, the HED high voltage lead should not be disconnected. 

I was having same fault(HED fault) in two GCMS. Replacing HED PS solved one GCMS issue, but the other did not. 

I checked the PFTBA solution and it was enough. 2 hours bake out was given. But still it was showing same, HED fault.

What more could be the issue?

There could be issues with either control signals to the HED power supply or the power supplied to the HED power supply.  These electronic issues are down in the depths of the instrument and should be handled by a trained service engineer. Please contact your local country's Agilent service.

I had the same problem last week, after cleaning the source I had a HED Fault. I also saw a high baseline while tuning. According to Agilent probably a speck of dust some where on or near the HED or electron multiplier. Agilent has a PDF explaining how to clean those. After cleaning the HED and electron multiplier no more HED fault.

(+) Cleaning HED Detector Assemblies 5975-5977.pdf - Files - GC/MS - Agilent Community