Have recently gotten +/-1.0 or so noise at higher end of temp program. Signal just jumps back and forth about 60X min have swapped columns/injection ports, cleaned fid/replaced jet etc. Any ideas? (haven't seen this in 20 years except when janitor plugged vacuum cleaner onto same circuit). Isolated power to GC on dedicated curcuit. Pretty sure not gases
By Anonymous on Thursday, March 29, 2001 - 01:05 pm:
Electrometer board going bad?
By Anonymous on Thursday, March 29, 2001 - 01:58 pm:
Who is the instrument manufacturer? With the detector gasses off, do you still see the noise when you run the temperature program?
By keith on Wednesday, April 11, 2001 - 04:36 am:
Seem's to be a connection problem with the detector cable or the board rod try tapping the detector and see if the fluctuation stops.
By Mark on Wednesday, April 18, 2001 - 11:35 am:
Do not rule out the fact that collectors, of which are usually spring loaded, tend to stick over time and may need to be replaced.
By Spencer on Tuesday, April 24, 2001 - 08:26 pm:
If you are in the United States, 60 Hz noise is usually "line noise" (think power line).It usually appears when something is electrically wrong with your system: i.e. ground loops, loose connections, improper shielding of your electrometer, stray capacitance near the electrometer, etc. Because the cyclic noise is only apparent at high temperature, I would suspect that the wiring in the oven circuit is interacting with your electrometer or main board components because when it's hot and/or heating, it's drawing the most current.
By Mike on Wednesday, April 25, 2001 - 12:10 am:
Your diagnosis may be correct but the noise in the original post was 1 Hz.
By Spencer on Wednesday, April 25, 2001 - 08:37 pm:
You are correct. I mistakenly read "60X min" as "60X sec"! Sorry Anonymous...
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