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Author Topic: MOD xbox controller with external potentiometers  (Read 3148 times)

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arcade_nut

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MOD xbox controller with external potentiometers
« on: September 27, 2013, 11:47:00 pm »
I'm trying to connect external 10k pots to a xbox controller.  I have 2 Namco GP500 machine and I want to convert to xbox.



I've replaces the two trigger and one thumb control pots with 10k pots.  The two trigger ones work great for throttle and brake.  The thumb pot of left/right steering has a huge dead zone and just isn't usable.  Is this input looking at voltage or resistance?

Here is a picture of my test setup.  Any thoughts on how to make this work?

PL1

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Re: MOD xbox controller with external potentiometers
« Reply #1 on: September 28, 2013, 12:53:29 am »
Welcome aboard, Arcade_nut.

The thumb pot of left/right steering has a huge dead zone and just isn't usable. 
Several things that could contribute to this:

Is the steering pot linear, log, or an S-taper? (probably an S-taper 1)

X-axis is how far the pot is turned, Y-axis is resistance.

Also, you might have a flaky potentiometer.

With power off, test the resistance (ohms) between tabs 1 and 2 or 2 and 3 across the full range of pot motion with an ANALOG multimeter -- digital multimeter sample times will miss spikes and dropouts due to the sample/digitizing rate.  :angry:

As you turn the pot, you should see a change in resistance similar to one of the curves on the chart.

A small s-taper flat area/dead zone makes it easier to keep a joystick/steering wheel centered.

The pot may have been intended for geared operation like the 60 tooth to 28 tooth gearing on the Star Wars yoke X-axis -- a 90 degree turn (15 tooth turn) of the 60 tooth gear on the yoke caused the gear on the pot to turn slightly over 180 degrees. (15 tooth turn)

On the Y-axis it is a 60/14 ratio -- 1/4 turn on the handles = ~1 turn on the pot.

Is this input looking at voltage or resistance?
If the original control had all three tabs connected, it is using the center wiper as a voltage divider.

If the original control only had 2 tabs connected, it is configured as a variable resistor.


Scott

arcade_nut

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Re: MOD xbox controller with external potentiometers
« Reply #2 on: September 28, 2013, 01:10:10 am »
Scott,

Thanks for the detailed reply and the welcome.

The steering pot is linear.  I'm using a P231-FC20BR10K for all 3.  The pot is new, although that doesn't mean it can't be flaky.

It is using 3 points so it is voltage divider.

I don't have an analog meter only a Fluke 29 digital.  I will get an analog meter to check the small pot I took off to see if it is linear.

The game reacts slowly.  When I turn it cc say 90 degrees before the game starts to turn, then it stays turning until I rotate the pot to 90 degrees in the other direction, it should move in a linear motion start turning back even at 89 degrees all the way back to zero.

Jay

PL1

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Re: MOD xbox controller with external potentiometers
« Reply #3 on: September 28, 2013, 01:54:34 am »
I assume you desoldered and removed the old analog joystick instead of piggy-backing it, right?

It almost sounds like there's something in the controller A/D circuit that is causing those symptoms.

Do you have a schematic or pics of the controller board connections?

The controller shell doesn't quite look like any of the ones at Slagcoin.   :dunno


Scott
« Last Edit: September 28, 2013, 02:05:14 am by PL1 »

BadMouth

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Re: MOD xbox controller with external potentiometers
« Reply #4 on: September 28, 2013, 10:18:58 am »
I've tested with 10k pots and 100k pots.  They both work, so the xbox360  controller must use voltage.  .

The controller does not have a built-in deadzone, at least not when connected to a PC. (I don't have an xbox to test on)
So the deadzone is either set by the xbox or the game.

I'd test it on a pc, then on a variety of games to see if there is any difference in the dead zone.
Personally, I think it's the game.

However if that's not the issue....

One thing to keep in mind is that the pots in the joysticks are made to sweep from 1-10k over a narrower range of motion.
Let's say 90 degrees for the sake of argument.

You're only using a small portion of the full travel of the standard pots which probably have to travel 300 degrees to do the same 1-10k.
The xbox is only seeing the joystick move a little side to side, not it's full travel.  So the deadzone will be larger in relation to the limited range being used. 

The way around this would be to use 100k Happ pots for Happ analog joysticks.
They have a custom taper and range of motion similar to the original xbox pot.
http://na.suzohapp.com/amusement_products/accessories/50-2032-00

I ordered ONE hoping to get a part number off of it and get it cheaper elsewhere.
The numbers is "built to order for customer" on the manufacturer's website.

If this is the issue and the throttle and brake work ok, maybe you could get away with only having to buy two.
I've never tried mixing 10k & 100k though.
« Last Edit: September 28, 2013, 10:25:08 am by BadMouth »

lilshawn

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Re: MOD xbox controller with external potentiometers
« Reply #5 on: September 28, 2013, 10:31:55 am »
pro tip for testing a log pot with a digital meter:

if at 50% you are at 5k ohms, it's a linear pot.

be aware sometime in the production of pots, they changed the lettering scheme of pots that swapped the designation that you used to discern if a pot was linear tapered or logarithmic tapered. Newer potentiometers will usually be marked with an "A" for logarithmic taper or a "B" for linear taper. Older potentiometers may be marked with an "A" for linear taper, a "C" for logarithmic taper.

I very rarely get a proper log pot. They are always marked "A" but it's always a crap shoot because if it's old stock, they are linear.  :banghead:

TL;DR - measure your pots to be sure they are proper.


jampot

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Re: MOD xbox controller with external potentiometers
« Reply #6 on: November 17, 2013, 03:53:37 am »
Hi

Did you manage to solve this problem with the thumb pots large dead zone and if so please can you tell me how??

What games is it possible to play with this set up and are you restricted to games that don't involve gear changes/shifts

arcade_nut

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MOD xbox controller with external potentiometers
« Reply #7 on: November 17, 2013, 08:36:37 pm »

Well I tried several different pots and could not get the steering to work well with the xbox. The throttle and brake are very good.  It steers better when the rider is tucked in.  I think it is just something with the xbox game.  I connected the xbox controller to my PC running motogp 08, and it works fine,  I used a 60 degree pot



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rmwilson

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Re: MOD xbox controller with external potentiometers
« Reply #8 on: October 21, 2014, 03:41:33 pm »
Looks like this guys was able to get it to work .. using Namco Cycles ( it looks like) and maybe not an xbox but rather a playstation maybe from the looks of the controller down in front of the bike on the platform. Any one know his set up?



Ryan

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Re: MOD xbox controller with external potentiometers
« Reply #9 on: October 21, 2014, 04:06:57 pm »
Looks like this guys was able to get it to work .. using Namco Cycles ( it looks like) and maybe not an xbox but rather a playstation maybe from the looks of the controller down in front of the bike on the platform. Any one know his set up?



Ryan
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TriAdX

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Re: MOD xbox controller with external potentiometers
« Reply #10 on: October 13, 2020, 11:19:28 am »
Did you ever get this working properly?

I just picked up a Super Hang On (Ride on) and wanted to try the same thing with an xbox1 controller.

Can it be as simple as soldering the arcade pots and buttons wires to the same points on the controllers board?  If I use an elite controller you can use Xbox settings to adjust dead zones and such...

I've got throttle, brake and left/right lean, and then 2 buttons (start and turbo).


rmwilson

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Re: MOD xbox controller with external potentiometers
« Reply #11 on: October 13, 2020, 01:08:16 pm »
I was using a Pc and the then using ultimarc uhid and it was working petty good had lost of trouble with the break but never looked into the POTS enough, I know the sega pots are more than the xbox so may not be the same...  Arcade_nut is still working on his proeject - he's come up with a no technique.