Hi, you're correct about 596-8 only D2 is on the board w/2032 batt like you mentioned. But 596-4 does have both D1 & D2 thats why I was asking as the legs are gone on both components, so would 1n4001 for D2 and 1n4148 for D1 be ok?.
This 596-4 board is in really bad shape. Some transistors are not original either and I don't know if they are compatible namely Q1(2sb731), Q3(2sb744) and Q18(2sd794). I'm not sure that I could find those but would any readily available equivalent of those be suitable? Btw, would these parts be the same on other revisions as well? If you could let me know, thank you again