Diodes on Daytona Gear Shifter?

[stevearcade]

Why are there diodes on my gear shifter? I know what they do but don't understand why they're there. I mean as far as I can see the microswitches on the gear shifter are just small microswitches, nothing else. Why does each one have a diode in the signal chain?

This is part of the cabling that comes from my gear shifter. Not sure of it's intended purpose!

Any suggestions?

Edit: Typo!

forum testing please ignoreConners2011-08-03 10:34:07

 

[Guests]

because the gears are in a matrix, 4 gears 3 wires
Conners2011-08-02 20:35:33

 

[stevearcade]

That explains the number of cables seeming odd! Right!

I don't really understand matrixes, but understand enough to follow what you're getting at. Will have been done because of the how the PCB was designed to receive the signal?

I mean, so if/when I get round to making this cab a Model 2 Emulator machine (sadly don't have the funds to do a full restoration), the diodes won't be necessary, as the switches will suffice for interfacing with, say an Ultimarc APAC.

Thanks Conners, interesting stuff.

 

[trm]

As long as you have enough input channels for the number of switches you've got then you'll be fine. You just use matrices or multiplexing when you need to encode more on/off states than you have actual input ports.

 

[stevearcade]

Right! Computer keyboards use them right? I have a mate who tried to explain this to me when he was building a keyboard hack for another friends MAME cab. But while he's very knowledgable, (he has an eprom programmer and everything - blew my mind when he told me as my thoughts straight away went to fixing boards

) he's not very good at explaining things. Mumbles, doesn't finish sentences, draws scrawly pictures that make no sense

.

But thanks guys. This makes it seem all just a little less complicated and daunting. One day I'll get my hands on a game I like with some faults (or my SF2CE board with develop a problem), so I can really nerd up

.

 

[trm]

The technical term we prefer over "nerds" is "a quiet man, never seemed to cause any trouble. We're very surprised that the police found so many prostitute's corpses. Seems like such a nice guy"

If you're keen to get into this sort of thing then a) I've got a tonne of dead boards I'll happily pick some nice ones from and send down to you and b) I've quit my contract and am looking at 6-12 months off so have plenty of time for posting help.

I understand that it's a very similar process to keyboard matrix encoding, just on a smaller scale.

 

[stevearcade]

Dude! That's an awesome offer. You haven't by any chance got a faulty Juno First

. I know that might be cheeky request, it's a cracking game

. I don't mind taking a crap game you won't miss, like a pocket gal or something

. If it means getting my hand dirty with chip and resistors, I don't mind.

 

[trm]

I'll have a look. I think I have a bootie Juno First but I also have a feeling it works. I'd recommend something original, older without surface mount and preferably without customs, and definitely with schematics so you can really learn from it.

When it gets too hot in my workshop I go into the garage and spend an hour or so sorting through the 500ish board in there so will keep an eye out when I go digging tomorrow.

 

[stevearcade]

Ok. That would be awesome man. I mean anything to get the ball rolling. I'll trust your judgement. I'll be your Daniel-San and you can be my Mr Miyagi

.