Jennings J400 help

[ramegoom]

Just another thought or two: The edge terminals on the logic board seem to have been "shortened" by wear and tear, or possibly by corrosion in the receptacle. You would need to take a real good look at the card edge receptacles and look for corrosion damage.

Your goal is to get the "Call attendant" light to be off, and the "insert coin" light to be on. The reset button the the board along with the reset key on the side will help you get there. Without a battery, you may need to reset the board every time you power up the machine, so a battery would be a good idea. Otherwise, it'll run without it. I have had logic boards in worse shape than yours and managed to get them working correctly.

So, before you power it up, make sure the 5V is stable, and you should be good to go. Here's some insight to the relative reel coil driver transistor locations on the logic board. Note the yellow capacitor shown is the "cap fix" to eliminate the battery. 2.2uF:

[ramegoom]

And here's an expanded view of all MJE800 transistor functions, helpful in troubleshooting. It's a large image and the yellow text spells it out, but you need to zoom in to read it: