That doesnt look like a Cadash board running.
With Cadash (and all Taito boards of that era) the most likely cause for missing colours or missing video is the very fragile TC007RGB SIP package, which on Cadash is towards the back of the board. Often these SIPs are knocked clean off the board and they snap off so cleanly that it is hard to see anything missing at all. If you are missing colours then the chances are it has fractured pins. I repaired a Rainbow Islands board with a colour fault caused by this SIP...
http://retrocomputermuseum.co.uk/forum/index.php?topic=1811.0
...and have seen many boards with it completely missing.
First place you should look!
The board in the auction above has other issues beside this tho - the communication error is because the DIP switch is set to (dual mode) whereby two cabinets were connected by a serial cable to give 4 player simultaneous play.