Pinball Repair - Fixing Switch Matrix Errors

[@pezjohnson]

Nice work through. Thanks for making the video

[@jvds6660]

Good video! If you have time, it would be great to have a video how to test coil within the game (by hot-wiring them). I always am a bit afraid to do this, specially with a B/W flipper coil with 3 wires…

[@davesthinktank]

Not a bad idea. You can definitely activate a coil by shorting it to the ground braid, but you can also blow a fuse or worse if you do it wrong!

[@jvds6660]

@@davesthinktankyes…and that’s where I’m afraid off

[@Pinthetic]

If this is Flash Gordon Switch 37 is the top thumper bumper.

[@davesthinktank]

True. The switches in the manual and the switch test were all originally renumbered from 1 to 40. In the code though, they are numbered zero to 39. the Arduino code I started with, including the switch test, numbers it this way.

[@waynegram8907]

Why would bad contacts measure 0.5vdc in DVM diode mode? The MPU is sending out a strobe signal but what is the strobe frequency and why is the strobe frequency at that particular frequency?

[@davesthinktank]

I wore out a contact on my Arduino, messing up address and data lines.

[@waynegram8907]

@@davesthinktank I'm talking about the pinball game MPU, NOT your Arduino board MPU, The pinball game MPU has a CPU chip that is sending out a strobe signal at a particular frequency plus at intervals spacings that is strobing the columns of the switch matrix which the rows RETURN the strobe signal back to the CPU to READ the switch matrix. My Question is what is the strobe frequency and why is the strobe frequency at that particular frequency?

[@davesthinktank]

Testing the diode gives either 0.55v or 0 v, depending which direction you are testing. If you are expecting 0v, and you don't have a good contact between the multimeter and the diode, you will get a reading of zero, which may be incorrect. This is important to consider, as you are often contorting yourself to look at the dark recesses of the underside of a playfield, and may not even be touching the correct wires.