Hi Win, The "power on" signal (X) is driven by a 7417 (open collector buffer), with a pull-up resistor. The 7417 in turn is driven by the COPS 421 microcontroller (which implements the soft power switch among other functions). I'm not sure whether "power" on is presented by a logic "1" or "0", but you should be able to turn the power supply on by connecting that signal either to ground or to the +5V standby power. Neither should harm the power supply. Camiel. -----Original Message----- From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Win Heagy Sent: zondag 8 juli 2012 23:00 To: cctalk at classiccmp.org Subject: Lisa Experts: Lisa 1.8A power supply test? Can anyone recommend a quick (safe) way to test a Lisa 1.8 amp power supply outside of the Lisa chassis? It appears that something (maybe pin X) needs to be jumped to make some of the power supply function outside of the Lisa? The only pin I currently get a reading from is pin 20 (~5.62v) which appears correct. I'd like to test more of the supply, if possible, prior to powering up the Lisa. Pointers appreciated. http://imgur.com/idthc http://imgur.com/PcFF6 Thanks, Win