Agilent 6643A producing a few volts when output is disabled.

[NoisyBoy]

Hi community,

On my 6643A, the output is delivering a voltage of a few volts (less than 7V) only when the output is disabled.  However, once I enable the output, then the output voltage and current is tracking exactly on the spot with the programmed value, everything seems to work fine.  Unit is set for Local sensing.

For those who work with Agilent system power supplies, do you have any guidance on what to check for?  I suspect there’s something wrong in the output stage bias/shutdown circuit in shutting down the bias voltage to the output stages, and to keep the supply output off. 

I thank you in advance for your helping hands.

[Hexley]

What happens to the stray output voltage when you have a load attached -- say, a 10-ohm resistor?

Or if you feel brave, what if the output is shorted to ground through a beefy ammeter -- then what is the short-circuit current?