No Signal or Noise on Agilent MS Trap

[DeniseHeinz]

We have an 1100 trap that was working fine until last week. It's an older system that I've cleaned up 3 years ago, but I haven't changed any internal bits. The system has a complete flat line during runs... no background noise, nothing. I took out the capillary and cleaned it up, and then we had signal again for a few runs. But, 5th injection on this latest analysis and the signal has suddenly flat lined again.
Diagnostics are passing for everything except 5v DC.. it was reading 4.2. We have seen this in the past and the system operated fine.
Any thoughts on what it could be? Or a place to start looking at it? I was thinking the electron multiplier or a board.. boss wants to tear apart the trap.

Thanks in advance!

[nbik]

You see this picture in both modes, positive and negative?
Do you have any current on the capillary?
It can be also signal cable or acqusition electronics. If you don't have any noise i don't think it's dirty trap, because you don't have any signal to detector.
And as i remember there were troubleshooting in 192.168.254.10 tool for bad voltage. May be you will find out there what board you need to replace.

And my main advice - call to service, it will be better)

[DeniseHeinz]

Yes, we have voltage on the capillary and it's in both modes. This is definitely an intermittent problem. I'm going to check all the leads and ensure everything is tight. I've seen this with LCs when the signal cable goes bad too. I will get in touch with a repair guy if we can't get this sorted out this week, but we are a very small start-up company that loves to do the work ourselves. (Although, this may be beyond my abilities to properly diagnose)

[DeniseHeinz]

So, while the system is showing no signal or noise, we are able to jiggle a co-axial cable, I believe its the signal amp feedthrough, just below the electron multiplier horn and generate a small amount of noise. So, can I assume our connections to the computer/signal cables are working fine?

We are still trying to get in touch with a repair man that maybe has a manual for this system. Otherwise, I'm hoping to hear from my forum experts.

[James_Ball]

So, while the system is showing no signal or noise, we are able to jiggle a co-axial cable, I believe its the signal amp feedthrough, just below the electron multiplier horn and generate a small amount of noise. So, can I assume our connections to the computer/signal cables are working fine?

We are still trying to get in touch with a repair man that maybe has a manual for this system. Otherwise, I'm hoping to hear from my forum experts.

If it is anything similar to the GC/MS from Agilent that would most likely be the signal out cable from the multiplier. It sounds as if maybe your Electron Multiplier has died. I have had them either die a very slow death that takes months as the voltage rises to maintain sensitivity to just going flat line in the middle of a run.

A quick search shows that the 1100 ion trap uses the same K&M style multiplier as the 597x GCMS so I would suggest replacing the multiplier as a possible fix.

[nbik]

So, while the system is showing no signal or noise, we are able to jiggle a co-axial cable, I believe its the signal amp feedthrough, just below the electron multiplier horn and generate a small amount of noise. So, can I assume our connections to the computer/signal cables are working fine?

We are still trying to get in touch with a repair man that maybe has a manual for this system. Otherwise, I'm hoping to hear from my forum experts.

If it is anything similar to the GC/MS from Agilent that would most likely be the signal out cable from the multiplier. It sounds as if maybe your Electron Multiplier has died. I have had them either die a very slow death that takes months as the voltage rises to maintain sensitivity to just going flat line in the middle of a run.

A quick search shows that the 1100 ion trap uses the same K&M style multiplier as the 597x GCMS so I would suggest replacing the multiplier as a possible fix.

It's not the similar to GC\MS.
Usually you have low signal when you have problems with multiplier.

So, while the system is showing no signal or noise, we are able to jiggle a co-axial cable, I believe its the signal amp feedthrough, just below the electron multiplier horn and generate a small amount of noise. So, can I assume our connections to the computer/signal cables are working fine?

We are still trying to get in touch with a repair man that maybe has a manual for this system. Otherwise, I'm hoping to hear from my forum experts.

From troubleshooting guide of Agilent:

If you have no spetra:
Check signal cable.
No noise?
Yes. Problem with acquisition electronics.
No. Problem with ion control electronics.

[DeniseHeinz]

Do you have the PN for the troubleshooting guide you were using? I put in a new electron multiplier, new capillary and springs, cleaned up the desolvation assembly and skimmer, double checked that all leads were attached. And, recalibrated. We are now seeing our ions of interest, but mid run or randomly, the peaks cut out and all we are left with is low level electronic noise.

I think previously we were seeing nothing at all because the electron multiplier was shot. Now we have some noise (but not ions from what I can tell) with the fresh EM, but still the same problem.

[DeniseHeinz]

And another possible clue: when we turn on isolation for an ion, it causes the signal to drop off to the electronic noise. Sometimes just restarting the software will correct the issue, but not consistently.

We also do see occasionally on the diagnostics when the signal is gone, that a number of our voltages are failing. However, running the diagnostics a minute or two later, they are fine.