Hi
There are two X-synth board, Icon X-Synth for Icon hardware, with HE10 16 pins connector, and another one, similary to Icon X-Synth hardware (same name ?) with JST 8 pins connector for CME hardware. On my Icon board picture, you can see pinout for JST connecteur for CME.
I tested JST and HE10 connectors with ohmeter. I found GND and DIN4 and 5 on 2 connectors but not VCC. I tried to test all others pinout on my board where there are no physical connector, I don't find link too with HE10 VCC. Perhaps, the two boards use different input voltage for each hardware keyboard.
If I remenber, in the CME guide (I don't find it again), it used 2 connectors, JST and another one
Warning, I don't test it with power supply, only with ohmeter (with 0 ohm detection)