I recently got the opportunity to work on a Roland System 100 and decided to take some photos of these modules as they are somewhat rare. They are completely enclosed with an 8 pin DIN power connector in the rear.
The 140 is a dual ADSR with a LFO so they packed a lot of functionality into a single module.
Inside are two large PCBs, one for the panel and one for the main circuitry. The rear panel power connector is cabled to the PCB.
The PCBs are well constructed single sided with lots of space. The PCBs are phenolic with no solder mask. The main PCB has been fully tinned most likely from flow solder. The panel PCB appears to be hand soldered.
Here is a bit closer look at the front PCB and the cabling between PCBs. These had a lot of hand labor in assembly.
The rear view shows the power connector and the two screw holes for mounting the rear enclosure of the module.