Here’s a collection of projects that don’t really fall into one category.
The Curtis CEM5530 is a 30 channel sample-and hold IC that was used in several instruments. Unfortunately they have a design flaw that causes one or more of the S/H channels to become unstable and eventually stop working altogether. I came up with a board that drops in place of the CEM5530 and, as an added bonus, has two extra channels that can be used. I installed four of these in my Prophet VS keyboards as the CEM5530’s in them were having issues.
HD6475328 programming adapter
According to Hitachi’s data sheets, with the proper adapter you can program the on-chip EPROM in a H8/532 (used in the Yamaha SY99) just like a 27C512. So I used some spare board space in the SY99 power supply to make this handy board.