jimp discovered his two C64 PSUs do not have all 7 pins in the plug, only the 4 required (9v AC, 9v AC, +5v, Gnd) and actually have the +5v pin in a different position to my PSU, TK's diagram of using a C64 PSU (http://www.ucapps.de/mbhp/mbhp_4xsid_c64_psu_optimized.pdf) and unfortunately the socket pin used on the MB-6582 Base PCB. As can be seen in these references: http://www.hardwarebook.info/C64_Power_Supply http://personalpages.tds.net/~rcarlsen/cbm/pinouts.txt Pin 5 is shown with +5v to be connected always, with pin 4 either not connected or the same +5v. jimp's C64 PSU only has pin 5 and not pin 4. But on my PSU, pin 4 has +5v and pin 5 has nothing, and this matches TK's diagram of which pin has the +5v, and so naturally I designed the MB-6582 base PCB to match. This means jimp's PSUs (and maybe others!) won't work with the MB-6582 base PCB without a little "fix" :-[ This is just a warning to people who are starting to solder/use their PCBs that you should check the expected voltages are coming out of your PSU. I've been too busy to write up the complete construction guide including things to test like this... ::) You should be fairly safe to solder a thick insulated wire between pins 4 and 5 of the power socket on the base PCB, to get +5v from pin 5 across to pin 4 and the rest of the PCB. But don't do this unless you fully understand why you are doing this - I'd like to get some more info before I publish this as an official "everyone do this" fix. Pin 4 and 5 are the two pins closest and on either side of the pin in the middle. Quick hacky diagram until I do something better (bottom of PCB shown): [tt] O O O O-------O O O [/tt] I'd like to know which PSUs are affected. Is this a Europe/Australia vs. U.S.A. thing? Or a 220v vs. 110v thing? Why does my PSU have +5v only on the optional +5v pin and nothing on the always +5v pin (according to the pinout diagrams)? Did TK draw that diagram because his PSU and many other "Eurpoean" ones are the same as mine? Or does his have +5v on both pins 4 and 5 and just happened to choose pin 4?