You are watching a circuit designed to replace the infamous and unobtainable Curtis CEM5530 30 channels sample and hold integrated circuit used in Sequential Circuits Prophet VS, Studio 440 and in Keytek (Siel) CTS-2000.
The original chip had temperature issues and some users placed a heatsink on it which can prevent its failure.
Anyway, I had a synth to repair and couldn't find a 5530 so I designed a small PCB (according to Wine Country instructions). This PCB is just a couple of millimeters wider than the original PCB and uses 4 NEW OLD STOCK SSM2300 8 channels sample and hold integrated circuits in a machined socket. There's an obvious advantage on using sockets for the SSM2300: you can easily replace one if it fails. 
This module is a direct replacement, no adjustments are necessary.

The chips are tested prior to shipping in my Keytek CTS-2000 (last picture).The original CEM3350 shown in some pictures is not included.
The price includes registered (tracked) shipping to any part of the world. It is shipped from EU.