New (to me) HP 3421A DA/C Unit, some questions

[4ster]

(05-11-2017 09:50 PM)Dave Frederickson Wrote:  Error 7 is caused by having something connected to the Mux board when the power-on self-test runs. The error symbol is cleared when the four Error Status Registers are read.

Dave

What has me puzzled is that with the same initial conditions, i.e. nothing connected to the instrument, when I power up on line power there is no error 7. When I power up on battery power an error 7 occurs. That error clears by re-running the FP program.

Thanks for the links.