We currently have two Agilent detectors (G4212B and G1321B) sending data from their Analog Out ports to two separate Analog In ports on a third party light scattering detector (Wyatt HELEOS II). The FLD data transfer looks good, but the UV cable is picking up interference that appears as a sine wave (~0.15 mV amplitude) which shows up only in the UV data collected in the light scattering detector (see image below), but not in the data directly recorded in Agilent ChemStation. The problem was not present in last year's data on the same hardware setup, but only appeared starting this year.
We have been troubleshooting using the G4212B DA Converter test function in Lab Advisor. Physically removing the FLD->HELEOS data cable seemed to eliminate the issue on the UV data cable. Unfortunately, this doesn't work for our application since we need to collect both UV and FLD simultaneously in the light scattering software.
None of these other tests produced any substantial improvement:
- Turning off the power to the FLD while leaving the physical wire connected between the FLD -> HELEOS ports.
- Swapping the UV/FLD cables while keeping both of them plugged into the HELEOS.
- Using a shielded UV->HELEOS cable.
- Replacing the HELEOS power cord.
- Rearranging which power outlets the power cords are plugged into (all are currently plugged into one single UPS unit).
Based on the G4212B manual, we are not sure if there is some kind of grounding issue on one of the three detectors involved? If there are any suggestions on further modifications we might attempt to eliminate the signal interference while still being able to send both UV and FLD signals, that would be greatly appreciated.