Response from Jonathan: Jim,

Unfortunately Donkey Kong and Donkey Kong Jr. do not have a test/service menu that generates monitor test patterns. The service button that’s usually found in these cabinets gives service credits that do not add to the coin counter and are usually used for testing by the operator. All of the other options for the game are modified through the dip switches on the board. Please see our post on Adjusting Dip Switch Settings On A Board for more information.

Now, you can purchase a standalone test pattern generator for arcade monitors. There’s a guy that sells them on the KLOV arcade forums for around $80. Here’s a link to the thread to purchase: http://forums.arcade-museum.com/showthread.php?t=297247

Hope that helps. Thank you for your question and good luck with your repair.