Chromatography Forum

On Friday, I had a blown filament. I was receiving error code “No emission current @1.87, error code 8” I changed both filaments, cleaned the source, and allowed it to pump down until Monday. I came in on Monday, and attempted to tune, but received the error “Not enough signal to begin tune”. The first problem I noticed was the fan on the GC was not working. After having this replaced, yesterday, I attempted to tune again and received the error “Not enough signal to begin tune” I took the instrument down and checked all of the electrical connections. Everything looked good. I replaced part no. 60142. Attempted to tune again this morning and received the same error. I tried switching filaments, but no peaks found on either. Any advice?

Are the MS vacuum and temperature OK?

yes

What's the MS vacuum reading? On the manual tune sreen, click on profile or scan, do you see peaks?

vacuum 11mtorr, no peaks

vacuum 11mtorr, no peaks

What's the error message?

Not enough signal to begin tune

(note I haven't used a 5972 and some of the features I mentioned are probably not present in your SW, the advice should still be good though)

Do you have a copy of your last "good" tune? Open the software and go to the tune and vacuum control view, then open the manual tune window and compare your current settings to the last good tune. Turn the PFTBA on and listen for the solenoid to make a click sound, then press prof (profile) and you should be able to see the ions from the PFTBA. If you see nothing but baseline it may be that the current settings to 'find' the ions are not optimal anymore because of the source cleaning. In the same tune and vacuum control view if you go to file > view tunes it will pop up several graphs and a excel version of all recent tuning parameters. You'll be able to see if anything has drastically changed recently.

If you get an error when you try to tune it is possible that your new filaments are bad (unlikely) OR they aren't electrically grounded from the source body like they should be. If you have a volt meter you can take the source out and take one probe to each 'prong' of the filament and then one probe to the source body and make sure you don't get a valid low resistance (should be unity/infinite resistance if they are indeed grounded.) You can also take the filament off and put one probe on each prong which SHOULD give you a low, finite resistance (usually like 5 ohms or so.)

It sounds to me like either no signal is reaching the detector portion of the MS or no ions are being generated because the filaments are not getting the correct voltage.

Is the electron multiplier voltage (EM Volts on the tune print out) normal on your good tune? It should be somewhere between 800-2200 depending on the age of the EM.