I have a Delts plus Xl system or as a grad student calls it. "That damn
thing". Magnet control has been an ongoing issue with this instrument.
In the past a fan has been placed to blow air across the DAC board to
mantain function. Apparently there is a issue with the card overheating
. However this solution is no longer working.

I can regain control for a brief period of time after a hard reboot of
the instrument. I can watch the magnet go to its max and min and measure
the voltage on the DAC card cycling through. I can open the bellows to
the source and get a good signal. But  it quickly loses the signal and
the ability to control the magnet.

This is the 3rd DAC card and 2nd magnet regulator in this instrument but
the boards to not seem to be the problem what is actual cause of the
problem is a mystery to me. I hope someone can point my in the right
direction.

John Hart