Noise on PCI-6229 AI

[ozfit]

Hi
I am using an M-series PCI-6229 card. LV8, WinXP.
The problem is with the AI recording.
When I record 2 channels (any 2) the signals are clean until the higher channel (eg AI1) exceeds the lower (AI0) by exactly 10V. Then they develop a high frequency noise of about 2 Volts that persists even if the signals return to less than the 10V thresold (eg 0 Volts on each). More bizarre, the noise disappears instantly when the lower channel exceeds the upper by about 12V but returns again at the same 10V level.
It does not matter whether it is Differential, NRSE or RSE mode. Isolating the signals does not change things -it happens with two 9V batteries. Grounding all the other AI lines does not fix it. I've tried the SCB-68 and BNC-2110 interfaces.
Any ideas before I throw the card away?
RF

[PelleS]

Hi Ozfit,

I'm not sure what exactly produces the noise but since your board is only operative up to a voltage of 10 V according to the spec. https://www.ni.com/docs/en-US/bundle/pci-pxi-usb-6229-specs/page/specs.html my guess is that you overload it.