Hello; my girlfriend has a BK we picked up a year or so ago; her family had one when she was a kid and wanted for her collection. My experience in dealing with games has been newer (90's and newer) and older (one old EM game I have), so this era of machine is new to me (electronics, but weirder than I'm used to!).
It has been working fine, but a while back the Start button stopped working. It's been in freeplay, but even adding credits, the button doesn't operate. Thinking it was just a dirty switch, I tried cleaning it, and then even jumpered it with a piece of metal, and it's not starting the game. Also confirmed the physical switch seems to work fine by testing it with a multimeter continuity test.
This seemed odd to me, so I've been mining this thread for more info, and see there's a whole concept of a "switch matrix".
Am I correct in understanding that if one of the other switches in the same column or row as the start button is not operating, it can also stop the start button from working?
I see this general Williams guide mentioned in the thread: http://www.firepowerpinball.com/downloads/FlipperManual.pdf
I had a problem on my BK a while back where the start button wasn't working. I checked so many things until i finally looked at the switch matrix and realized i had to check every other switch on the same column and row as the start switch. Sure enough it was the ball-roll tilt on the left side of the cabinet had a wire broke off (same row as start switch). That's when i finally 'got' how the switch matrix works, and perhaps more importantly: how to troubleshoot it.
Quoted from frunch:
Those are the correct connectors.
Are you familiar with the diagnostics for the game? You have to use the switches on the coin door (open the door, you'll see 3 push-button switches on the 'back' of the coin door)... If you have the manual, you can follow the instructions from it. If not, the manual can be downloaded for free at ipdb.org (search for Black Knight). Basically, you push the middle switch into the down position (it will stay down until pushed again, which will pop it back up), then push the 'advance' switch to the right of it. That should start the display test. Push the middle button again so it pops back up. Now, pushing the advance button again should begin the sound test. Pushing advance again starts lamp test. Pushing it again starts the solenoid test. Push the switch again for the switch test. If any switches are being activated, the number of the switch(es) will appear in the credit/ball count display (refer to switch matrix diagram in manual to decipher which switches it detects are closed).
I would start the switch test, then run the jumper between a column pin and row pin and check the display to see if any number appears. I'd probably try a working column first, and make sure it registers a switch closure (a number will appear on a display) when the jumper is on any row pin. That way you'll know you're doing the test correctly. Then try running the jumper from the pin for column five and see if it registers a switch closure when the jumper is on any of the row pins. If no numbers come up, then we know the chip Schwaggs mentioned (IC18) is the most likely culprit.
In looking at that FlipperManual.pdf above, I don't see where these "pins" for the "switch matrix" would be, where I might be jumpering between. Is that in the backbox somewhere?
Quoted from frunch:
Have you verified that the credit button (aka start button) is working in switch test? It's switch 3 on the switch matrix chart:
Aha, good to know the start button == "credit button"!
This post has a picture of the "switch matrix":
Quoted from mwsmith:
Example from BK manual:
Shorted diodes (or an incorrectly wired switch) can cause "rectangle" switch matrix problems as follows: The lower left 3-bank upper target is down (switch 27), and lower right 3-bank center target is down (switch 30). A ball enters the lockup trough making switch 43, a shorted diode at switch 27 would cause switch 46 Playfield Tilt to be (incorrectly) indicated. Note that the "rectangle" is always completed with an incorrect switch diagonally opposite from the switch with the shorted diode.
So, I think my plan is to:
- Try and get into switch test mode
- Test all of the switches in column 1 and row 3
- See if I can find where these switch matrix "pins" are to possibly jumper (still not real clear on this bit)
- PROFIT (oh, wait)
- Try and identify which of these switches (because it doesn't seem to be Start/Credit button switch itself) is not working (would it likely be OPEN? Or CLOSED?)
Seem about right? Thank you!