USB 6221 AO ports not functioning

[jmansell]

My 6221 is not responding on the analog output ports.  It is pinned to ~-7 volts.  

It was working earlier.  I tried rebooting the computer, resetting the device, and using the MAX to command the device, but this did not help.

How can I fix this?

[AnalogKid2DigitalMan]

Have you tried running the self-tests in MAX?

-AK2DM

[jmansell]

Yes.  The self test passes.

[EricS.]

Have you tried unplugging the 6225, waiting about ten seconds for MAX to recognize the device was removed (shows a red X), and then plugging the 6225 back in?

What do you have connect to the USB 6225 output ports?  Are you reading the seven volts using a simple hand-held DMM when testing the output voltage between AO0 and AO GND?

[jmansell]

We have tried unplugging and waiting for it to lose connection to the PC.  We even left it off all night and tried again this morning.  

We measured the voltage with a DMM and an oscilloscope with a BNC connected to either the AO1 and AO0 ports.  

[EricS.]

This resulted in an RMA.  Something the 6221 (not 6225 as I mentioned in my previous post) was sending voltage to failed, which we believe sent a surge into the 6221 and caused it to fail also.

[jmansell]

Thanks for your help in debugging!  The "self calibration" step was the key to completing the diagnosis.  Thanks again.