Chromatography Forum

So I have been battling with an epic problem related to a sporadic "HED Fault" This happens about 30-45 minutes into a run, sometimes longer sometimes earlier. I have followed the advice on the forum as well as from agilent and this has led me to.

1) Clean HED
2) Replace HED power and control cables
3) Replace entire HED assembly including electron multiplier

Still when I run the machine I get the same fault, which brings me to changing the HED Power supply. I have heard that while generally you can get an "HED Power Supply Fault" sometimes a bad power supply can also cause an "HED Fault"

I do not have a service contract so I would like to do the work myself. It seems fairly straight forward to replace, other then the care that needs to be taken with high voltage equipment. Can anyone attest to this being a easy job? Are there any suggestions or pitfalls you can make me aware of?

I guess before I even go down that road I does anyone have any other thoughts on what could be wrong, or does this diagnosis seem possible? It seems that it could be a bad board, but then we get up into $5,000-$10,000 parts that I will likely just have someone from agilent fix, but before that a gamble on another $1,000 part seems worth it.

Thanks!

I have never tried it on a 5977, but it has to be easier than on a 5971 which I have done before. Precautions will be to unplug the power cord and take all the anti-static precautions of grounding yourself and the equipment so you don't cause any sparks.

Testing the HED power would be difficult since you need a special probe connected to a volt meter to handle such large voltages.

If you can get a copy of the Lab Device ToolKit from Agilent it has a suite of diagnostics it will run on the boards and lenses that might also help locate the problem. It is usually only given to the engineers, but if you can find a copy it is easy to use.

Thanks for the input. I ended up replacing the power supply today and it took less then 30 minutes. Super easy to gain access, just had to bake down the MS and so far so good. I won't feel comfortable that it fixed my problem until it works well for a good week or so. However as far as the replacement, it was very easy. As long as you keep from killing yourself from the high voltage that is (so be careful, or if in doubt probably better to pay for a tech to come out).

Hi there, I am having a similar fault. Can you please guide me how did you manage to resolve this.
I don't have the agilent contract either.

Thank you in advance.

Alpesh