For anyone interested, after the power supply referb and chip reinstall the 680 was not fully functional. The front panel seemed to work properly, but examining page zero revealed that one of the 2102 RAMs was dead. This wasn't surprising and a quick replacement had front panel deposit and retrieval to RAM fully operational. Examining the contents of the 1702 EPROM with the front panel showed that the monitor code was in tact, but nothing was coming out of the serial port when the unit was reset. Looking around on page zero with the front panel after a reset revealed that the monitor code was running, so probably something was wrong with the serial port. I put a scope on the chip select lines of the UART and could see the monitor code polling for inbound characters. Was the UART dead? On a lark I put a probe on the receive clock pin of the UART. Nothing. I put it on the crystal. It was making a good signal. Turns out the 4702 bit rate generator was dead. It seems to me that that is a very odd component to fail. What surprised me even more was that I happened to have a tube of 4702s in my "random chips" box. I have no idea where I got them. I've never worked with a 4702 until now. The only small drawback is that the date codes on these 4702s are 1982. All of the other chips in the 680 have 1975 and 1976 date codes, including the 2102 I replaced. With the 4702 replaced, the monitor is active on the serial port. Now to find some _SMALL_ programs to push to it. Thanks to all for the power supply help.