Sega analogue stick & monkey ball

[John Bennett]

Forgive my ignorance on the topic, but with 5x, would that not place quite similar to a 1k pot (from 5k?). I guess the reason people are hacking things up is to keep everything ‘stock’ (with incorrect pots), without understanding exactly what the amp board does to the analog input profiles. Of course offset (not sure about that) and protection buffer (self explanatory I hope).
My understanding was the amp board helped with fine scale adjustments around the neutral position (where they are needed most for precise control)…

Oh I’m relatively ignorant to be honest, I cloned it and assumed it was just a simple non-inverting opamp buffer, which wouldn’t care what potentiometer was connected as it just sees the voltage. But there seems to be some subtlety I’ve missed, reading the threads. Opamps are good for subtleties.🤪

 

[Retroman839]

Is Olly not selling them anymore?

Sold out !

 

[yoganuggy]

Plus after calibration in the service menu, is there even a difference between the original JLK-GF2-AT stick with 5k pots and amp, the gundam JLK-GF2-AT with 1k pots and amp, or what about no amp or even the regular sega analogue stick (zombie revenge).

I can test all the above as I have the original monkey ball panel and a zombie revenge panel and almost all the bits for a couple of repros including several gundam sticks and 5k pots and JB's amps.

It would only be a casual comparison though. Yes I can finish the game on all difficulties but I would by no means be anywhere near the skill level of a speed runner. I can't even do thin right most string on advance floor 11 with the original panel. I can do it on the game cube though, that controller and version is the best IMHO.

 

[Retroman839]

Plus after calibration in the service menu, is there even a difference between the original JLK-GF2-AT stick with 5k pots and amp, the gundam JLK-GF2-AT with 1k pots and amp, or what about no amp or even the regular sega analogue stick (zombie revenge).

I can test all the above as I have the original monkey ball panel and a zombie revenge panel and almost all the bits for a couple of repros including several gundam sticks and 5k pots and JB's amps.

It would only be a casual comparison though. Yes I can finish the game on all difficulties but I would by no means be anywhere near the skill level of a speed runner. I can't even do thin right most string on advance floor 11 with the original panel. I can do it on the game cube though, that controller and version is the best IMHO.

Yeh I completed Gc vertion..
Totally agree that it could be the best vertion . controller makes it easier than the banna .
I found another zombie analogue stick to try .. I’m hoping it works
Would have tested tonight but monitor decided to play up!

 

[John Bennett]

Ok, well this is the circuit sketched-out in a way that might look a bit more textbook. It's a non-inverting amplifier circuit with an offset. The gain is around 5x.


The general gist is it amplifies the hell out of the signal going into it, so the pot can't be moving much to go full scale in the game.

If you simulate a sweep of all possible voltages from a 5V pot (resistance doesn't matter), only about the central 20% does anything (between the yellow markers).
I can't see what electrical difference having a 5k pot makes to a 1k pot.
Going off that thread on A.P., it just looks more like the two types of sticks have different ranges of movement, so if the Gundam stick doesn't have the right movement around that sweet spot in the middle (it sounds like it has way more movement), folk are frigging things with resistors (I must say, hacking up the amp board seems a bit extreme if you can put resistors in-line with the stick, or just do away with the amp board).

I suspect if you have the monkeyball stick but run it without an amp, it's working because of the adjustable calibration in the game, but it's going to be getting a much smaller voltage range into the game (20%), so it might be more prone to noise/jittering.

That's what I think anyway, happy to learn more if I've messed up.
LTspice file attached for anyone who wants to muck around.

 

[Retroman839]

Yeh my stick was jittering and now
Stopped on the push and pull axis ..

I’m freaked out that it’s stoped working .. but maybe that just how it is it haze t been used for years !
I have another one to try asap ..
1k pot standerd Naomi style zombie revenge stick ..

 

[nam9]

Thanks for the explanation @John Bennett . Gundam restrictor disc is 40mm while MB disc is 45.5mm.

 

[Retroman839]

Thanks for the explanation @John Bennett . Gundam restrictor disc is 40mm while MB disc is 45.5mm.

Yep my stick has broken analogue pots!
So
I now have a working analogue stick!!!
Ffs …. So testing now actually makes Sence!!!

I will add the analogue amp most likely Tomo and hopefully have a fully working game ..

 

[whitecomet]

Yeah i kinda realised that when it was pointed out to me. Got a couple of gundam sticks and bananas to make it now thanks to FrancoB and others that have helped out.

Will a taito io work or does it have to be sega io? I assume you connect analogue to this and then the amp to the io? Also i assume it refines the input??? So without it will justbe digial signals? Also whats the original sega amp model called please?

Again thanks to everyone who has explained. Im sure all this info can help others too.

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Are these for Virtual On? As you say about Gundam, if thats the case what Gundam game you playing that requires these?

 

[pubjoe]

Are these for Virtual On? As you say about Gundam, if thats the case what Gundam game you playing that requires these?

There are a few different cockpit gundam arcade games in Japan.



I bought some of these from Japan (not my pic but same things) with the intention of changing the grip to a 3D printed banana. Much cheaper than finding the real thing. We don't buy them for Gundam.