thanks to everyone involved in the useful info found here about the lovely sa synths.
i've now bent a sa-1, an sa-5 and i'm about to get funky with a sa-65.
they all look like they're based on the same two chips:
oki M6387
AN8053
the sa-65 has the same size circuit board as the mini sized sa's, it just has a big case and larger keyboard! i'd guess all the keyboards in the sa range have the same basic setup with other features added on.
i've found the deep crash on both the sa-1 and sa-5. it's incredible how varied the sounds are that it creates, some of the drones and beats make great samples and loops. for the sa-1 i used the photos in this thread as reference for the pin connections but did a bit more exploring on the sa-5. it looks like the deep crash is triggered by a variety of shorts on the circuit board and can often be triggered by simply soldering up a body contact. it often seems that a very quick short produces the most interesting crash so it's worth trying out different ways to make that trigger and not just throwing in a switch.
infact, i'd suggest body contacts are well used on these keyboards. body resistance seems perfect for some of the buzzy bends which are a bit too extreme if connected with just a switch. if you're looking at the board with the keyboard at the top, try connecting a large body contact to the lower pin of capacitor C5 (c393 in djsynchros pic?) and make up another large contact connected to some/any/all! of the last few pins on the oki6387. i've connected up pins 29 and 30. holding the two contacts (large bolts in my case) produces a lovely buzz which oscilates with the rhythms and sounds of the keyboard. the more you hang on to the bolts, the bigger the buzz. yummy.
the only issue i have with the sa's is the way the batteryies fall out when you open them up! must buy a battery box next time i go down maplins....