Rockola 478 no selection, no display

[Anthox]

Hi everyone,

I'm a french engineering student that bought a while ago a rockola 478 to repair. The issue i have is that on the credit unit, i have the 9.6 V light to indicate that the voltage is present (which i also checked with a voltmeter) but i can't select a disk and the display is not working. The test mode of the mechanism board however is working fine, so i can read disks but i can't select the one i want. So today i came across the project that was made to replace the microcontroller. However i can't find a really good step by step setup to replace the credit unit. The idea is to keep the current board but i can replace the microcontroller of the credit unit by an arduino board. Is there some code and pin placement schematic please ? 

Thank you very much

Anthony