The best way i have found to track down switch matrix issues is to first grab a copy of the switch matrix. I usually print a copy of it since i am going to mark it up. Then i go into switch test and check every switch and circle anyone that doesn’t behave the way it should. Wrong switches showing or multiple switches registering. Here it is important to keep track of your balls (pinballs in this case). Each one of those is activating a switch somewhere, most commonly the trough switches but could also be a physical ball lock. So mark all those down on the matrix too.
Now you can draw boxes around the switches you noted. Sometimes it is easy to identify the corners. Other times you can form more than one box. Your issue will be found in one of the corners of the box(es).
This narrows down where you need to look. Bad diodes will look good to the eye, and you need to pull one leg to test properly with a DMM. So this trick helps me get to the root of my issue quicker.
Bad diode, switch terminals bend over and shorting could be the issue. Recently i had a friend over and he noticed he was getting progress on the right ramp when he was hitting the left orbit. I never noticed it. So i did the trick above, then looked at the 4 switches i suspected. Noticed that the drop target under the mothership looked odd. There was a wire attached to the banded end of the diode which should not be. So i moved it to the correct terminal and bingo it was back to normal. I later found out that that wire broke off during a temp trade and must of got soldered onto the wrong terminal.
Gloucester Township, NJ
Sidcup
Melbourne
). There are PCB washing solutions but others just use a dish detergent (cheap degreaser)
Edmonton, AB
Breda
