Shut down h1oaf0, powered off I/O chassis, and replaced the 16 bit DAC card (on a carrier card) with a 16 bit PCIe DAC card.  Powered up I/O chassis and computer, measured voltages to verify we didn't have a repeat of last week's attempt.  The DAC card we tried last week was tested on the test stand and verified to be bad.  The DAC card used this week was tested beforehand and found to be good.