Date: Tue, 13 Aug 2013 19:53:50 -0500 From: Chris Elmquist <chrise at pobox.com> To: cctalk at classiccmp.org Subject: Re: KI front panel "VOLTAGE" adjust? Message-ID: <20130814005349.GG2148 at n0jcf.net> Content-Type: text/plain; charset=us-ascii OK. Thanks for all the input on the topic guys. It just struck me as interesting that they needed this adjustment on the front panel of the machine-- which implied that they needed to adjust it often. I guess it was a long forgotten art of making the machine easily servicable for their SEs :-) The IBM 360's (at least the mid-size and up) had voltage margin controls and a big meter on the front. Not adjusting mains voltage with a Variac, but there was a raise/lower knob and a power supply selector. The FE would run certain diagnostic loops while exercising the voltage margins. I believe the raise/lower knob ran motorized pots on the various power supplies in the back of the machine. Might have saved an hour over doing the whole procedure with a meter and screwdriver adjustment. I think that the raise/lower control was inactive unless the FE key was turned. Jon