Like any vintage audio equipment user knows, one of the main issues of having such gear is the occasional problem that will need fixing. This project started because of one of these problem. As part of a discussion on another internet forum, one forum member (lets call him Tom :)) approached me and asked if I would be interested in helping him sort out a problem with a Sansui 9090DB receiver. This is a fairly old, but highly regarded piece of audio gear. The problem he described was the main amplifier board, named F2624, which is also shared with a few other Sansui models. These boards became unreliable over the years, with problematic traces, difficult to obtain parts, and so on. At the time I was just a M.Sc. student and had the free time to do things just for fun, so I jumped aboard. Following a short discussion we’ve agreed we will aim at creating a whole new board, that will be a plug-in replacement for the original F2624, but with modern parts.
The first step, was obviously getting a hold of the schematic. However, as it turns out, it doesn’t really exist anywhere that I know of. This is because the schematic that was published in the Sansui service manual was of an early version of the board, and had a couple of mistakes in it. So what do you do when you can’t get the original schematic? You draw one yourself. So that is exactly what I did, by getting an original Sansui board, and going over it. Again, as far as I know, this is the only complete schematic of this board version that is available online. Therefore, I would like to share it with others who might need it one day to repair such a board. We (myself, and Tom) have already published this on 2 internet forums to make it available to anyone who needs it. I will also include it as an attachment at the end of this post.