Pinball Switch Matrix
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- čas přidán 8. 07. 2024
- Correcting a switch matrix problem on my "The Getaway: High Speed II" pinball machine.
Demonstrates a switch matrix problem caused by a spinner modification where the machine occasionally thinks a ball is in the supercharger mechanism when the left orbit shot is hit. Explores why pinball machines use a matrix for switches and how the switch matrix works. Uses that knowledge to diagnose and fix the issue.
00:00 Problem symptoms / gameplay
02:05 Switch tests
06:25 Problem identification
14:40 Switch matrix rationale
17:06 Switch matrix theory / construction
22:23 Switch wiring
24:12 Problem diagnosis and fix
27:22 Spinner removal
29:06 Spinner re-wiring
30:26 Spinner reinstallation
30:55 Testing the fix - Hry
Excellent explanation in layman’s term! Thank you
Interesting watch, I own a Getaway HS 2. I did a lot of mods to mine, the spinner is interesting but I don't think I woud add one to mine especially when it wasn't designed to have one in this game. I am thinking the spinner is what is causing your switch problems.
Super helpful explanation... Im in the middle of trying to add mods and use roll over switches to trigger timer relays.. I have this same setup on my theatre of magic... I was going to piggy back one side of a switch and run an independent ground as part of the trigger but I'm not sure It will work now... neet to think this through
my question is whether i need a diode between the pos and neg trigger to the relay timer - jz801 timer relay.. it has reverse prevention built in which may do the job ?
The JZ801 might already have a flyback/snubber diode across the relay coil. If you can't find schematics for the board, maybe measure resistance across the relay coil terminals on the board and see if the resistance varies depending on the polarity of your leads. If it doesn't have a diode, then, yeah, I would add one.
I don't think adding an independent ground on a switch is going to work the way you want though. Maybe think about adding your circuit in-line with the switch, so the wiring goes:
row--diode--switch--circuit--column
That way when the switch closes, the current has to go through your circuit to get to ground on the column. Keep in mind the switch matrix is scanned many times per second, so the relay is going to try to rapidly open and close whenever the switch is held closed. The timer might not handle that, or the duration of the scan might not be long enough to hold the relay closed. If you have trouble with the relay, I'd look into an optoisolator. They might react faster than relays.
Kyle, What is confusing is that DC voltage/DC current only travels in one direction from Positive Vcc to Ground, so adding the Diodes doesn't make sense because DC voltage/DC current can't Backfeed and flow backwards from ground back to +Vcc. The Rows and Columns are using a Sensing circuit but not sure how the sensing circuit senses the rows and columns.
The current isn’t flowing backward, it’s just finding alternate paths to ground. If we apply current to one row at a time, and we ground one column at a time, and if we see current getting to ground on that column, then we know that the switch at the intersection was closed. But that only works if the current is only allowed to flow through that one switch. If current can flow through other switches, then it can flow AROUND the switch at the intersection and find a path to ground through any other closed switches, and it looks like the switch at the intersection was closed even if it wasn’t closed. To prevent that, we want to make sure that current can only flow from row to column, not from column to row. Diodes ensure that. Check out 19:20 for an example of current finding an alternative path to ground and how diodes block that path.
@@kyle5574 watch at time 24:30 you mention when the spinners switch is CLOSED the DC current can flow from Column to Row its colored in RED, which is not true because DC current can only flow from +Vcc to ground, from from ground to +Vcc. Why are you saying that the DC current is Bi-Directional that it flows from Row to column in GREEN and can also flow from column to Row in RED?
The current is still going from source to ground, even when it's going from column to row across a switch. Look at the picture a few seconds later. Look at switch 21 (upper right in the picture). The rest of the switches are fine, but the current is flowing "backwards" across switch 21, from column to row. Since we don't have diodes in this picture, the current is allowed to flow in either direction across the switches. In this case it's finding an alternate path to ground, around the open switch, and through 3 other closed switches. If the switches had diodes, the current would only flow across the switch in the correct direction and there would be no path to ground in this case.
@@kyle5574 Yes true the current is going from +Vcc source to ground even when the current is going from Column to Row across a Switch, ( this isn't considered backwards current flow, its considered an alterative path to ground by using column to row instead of using row to column). When DC current is flowing from Column to Row across a switch it causing "Ghosting errors" that is what other techs call it. The diodes don't prevent Anti Ghosting errors so if multiple switches are CLOSED the CPU has to register ALL the closed switches but the diodes don't fix or prevent Anti Ghosting errors. I don't think you have made a video lesson about Anti Ghosting errors for pinball switch matrix circuits.