[cctalk] Re: who has a computer of your very own

I bought this Japanese Altair clone <https://deramp.com/downloads/mfe_archive/010-S100%20Computers%20and%20Boards/00-Mac8/20-Mac%20Systems/Mac8%20EMIC%20Alpha%20S-100/Photos/> some years ago. According to the seller, it never worked right. He suspected that the problem was the 100VAC versus 120VAC that's in some parts of Japan. I found that it did work a little better with reduced AC voltage, but it never worked right at all. When I dug into it, I found that Vcc on the front panel was about 7V! Looking closely at the front panel's regulator, I noticed that the outline on the silkscreen was drawn with dotted lines. As I suspected, this indicated that the regulator and its heatsink were meant to be mounted on the solder side of the board. But they were mounted on the component side! Turns out that a 7805 kinda-sorta works if its output and input are swapped :-) I removed it and mounted it on the solder side, and the machine now works like a champ. 100VAC, 120VAC, either way. All of the front panel components survived this overvoltage, and the 7805 was fine. I can understand how the seller got this wrong - the manual and schematic are entirely in Japanese. He told me that he bought the machine around 1980 as a kit in Japan, and assembled the boards (not including soldering) on the plane ride home. Imagine that in today's high-security environment! Martin E. On Mon, Nov 24, 2025 at 11:51 AM Santo Nucifora via cctalk < cctalk(a)classiccmp.org&gt; wrote: