Took a little break on repairing this instrument but I finally figured out what was causing the baseline ripple on pump B.
The solvent filter was dirty....
The baseline is still behaving a bit strange on this instrument. Basically its flat for the 1st minute then injection peak happens and then after about 30 seconds drifts down and starts to flatten out and sometimes then start drifting back up. Its just weird. I'd post a picture of it but I'm not good at that.
I wonder if I should change the mixer configuration again? Basically I have option of 0.5, 1.7, and 2.6 mL for mixer volume. Right now I'm at 0.5 mL because that helped with gradient issues I was having but those issues were really related to the clogged filter and pressure jumping. My flow rate is 1 mL / min.
OR there is a leak in the oven valve. We have an FCV-12AH valve installed in the column oven that lets you switch from pumps A and B to pump C which we use for rinsing the column. But we keep getting an error on the column oven that says leak detected. Its kind of random and happens on long sequences and we aren't sure if its the heater leaking hot air or the valve leaking liquid. We don't see liquid but it could be leaking in the back? The oven temperature is 50 C it would kind of strange if the oven couldn't hold that temperature.
A big question I have though is how to know on Lab Solutions software when to PDA is being zeroed? Is it zeroed on every sample? Do you have to zero it manually before you start sequence? Something might be wrong with the PDA here too. Its set at 50 C too.