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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.

Thanks! I used frosted, 1SMD bulbs from Comet Pinball--the cheapest, most basic bulbs they have. They're in the GI section. Nobody uses them for inserts because they're NOT non-ghosting, but a benefit to LED OCD is that you don't need fancy non-ghosting bulbs. With LED OCD you get better ramping/fading performance with bulbs that don't have the non-ghosting circuitry. Plus that saves you like $0.20 per bulb.

T2 is one of the early WPC machines that still use the older style flippers. T2 used assembly C-13174. Every parts retailer is different, but you should look for “early WPC”, or the assembly (C-13174), or the date it came out (Jul 1991). …or with this video you could buy each of the parts for C-13174 individually to make sure you get the right parts! I’ve got T2 listed as using C-11626 at 7:00. That’s incorrect. It used C-13174. I made a note in the errata in the video description.

I don’t know anything before System 9. Cyclone is System 11 and uses C-11626 so this video has you covered there.

You can! I didn't know how to do it when I started. These videos pretty much walk through my learning process. Just doesn't show all the Google searches.

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.

No, unfortunately not. The parts I used back then are no longer available. Maybe someday I’ll redesign it to use modern parts. I’ll post an update if I do.

That's Sophie!

It's not cheap, but the improvement is significant. If you haven't already converted a game to LEDs, then the cost of LED OCD is partially offset by buying cheap LEDs. With LED OCD, you can, and should!, buy cheap no-frills LEDs. Without LED OCD, you have to buy more-expensive non-ghosting LEDs, and if strobing bothers you then you might need extra-expensive LEDs with a capacitor that tries to combat strobing. The extra cost of more expensive LEDs adds up when you're doing the whole machine--and you can totally avoid that with LED OCD.

@MrCuriousModding The ball should roll smoothly on to the flipper from the flipper return lane. The problem is likely that your metal flipper return frame is worn down. Cliffy makes enhanced flipper return frames to replace them and to help fill in the gap between the frame and the flipper. I installed them on my Sorcerer and made a video about them. czcams.com/video/7QIA64qRI6Q/video.html

Welcome to pinball, where the playfields are 6.5 degrees off horizontal, and the videos are vertical.

It'd be pretty cool to convert this machine into something with a more traditional playfield with mechanisms mounted underneath like that. As-is though, I think you'd run into some challenges. There's not much room between the playfield and the PCB to mount switches. You'd have to find some pretty small switches too since the ball is so small/light. If I was going to tackle something like that, I think I'd try to replace the flippers instead. It'd be pretty sweet to have little electronic solenoid-driven flippers instead of manual ones!

@@kyle5574 Actually I was thinking of using this on a fullsized pinball machine with missing backboard and CPU. Cut a slot in the playfield apron to house the score display. Mount this underneath playfield on the one side of the machine which would be plenty of clearance and no interference to any of the mechanical components by the flipper mechanism underneath. So as you're playing the game, all you have to do is look down by your left hand to see your score, instead of seeing it in the backbox. For the scoring itself, hardwire the scoring to the schematic of the wires of the actual pinball machine so you're still using and utilizing all the wiring from the targets of the game but to American Girl scoring instead. For all the solenoids, have them wired up to different power supply units 24vdc for flippers for example that run independently from American Girl. Just using American Girl for scoring only but also need to figure out how to convert opto sensors into accepting the switches I currently have for my pinball machine for pinball drain and ball location for example. If I can get over that last hurtle, then I can turn this project into a completed reality.

I over-engineered this one! I ended up abandoning the idea of powering them all. I just put lithium batteries in them instead. All the wiring was a mess and made it hard to take them off the shelf to play. It would have been really cool to turn them all on at once with a switch, and leave them running with the attract sounds, but the problem is that they don't stay on very long before they automatically turn off. So turning them all on is a pretty short-lived experience. Lithium batteries were expensive, but no more expensive than all those adapters.

@@kyle5574 Ah, well it happens! Still a good idea. Thank you so much for the update. LI batteries do sound like a solution that makes for a more playable display!

I don’t think I’ve ever managed to hit it more than 6 times to find out what happens after 7x! It does continue to light after awarding 7x, and it’s a decent value at 50k when lit, but I don’t think I’d go for it after getting 7x because it’s too hard to hit. Next time I have the glass off I’ll see what happens after 7x.

Cost might depend on the type of switch. Message Pinside user Sonic for information. Just for reference, the ramp switch shown in the video was $30 USD at the time.

@@kyle5574 Cool thanks!

I asked M&M Creations the same thing. Especially because I tried to test it with a multimeter and a ball and I couldn't get it to trigger. Their response was something like "That's the magic of MRS." The diode must be built-in. It works great in the machine and doesn't cause any issues with the switch matrix.

It's a great product and it works really well. Just make sure you spend some time test fitting it and testing it with an actual ball. It might not go exactly where the old switch was. It has to be in a spot on the ramp where it can pretty much span the entire width of the ramp. And it also needs to be where the ball is sure to be making solid contact with the ramp surface. That means it probably needs to go further up the ramp than the original switch.