How to test a pot?

[pmc]

I've got a set of pedals that don't work and am trying to figure out why. They connect to a wheel which is a USB device. The wheel and buttons work fine, the pedals act as if they are not present. So I started gutting things.

The brake and accelerator are each tied to a pot. Two of the three connectors on each pot are wired together so I believe that they act like variable resistors. There are only two wires running from each pot. And they run to a USB board in the wheel housing.

I did some poking around with a multimeter but I don't know what I'm looking for. Any suggestions? I'd like to verify that the pots are working properly and then go after the connections/wiring and then the USB board.

TIA.

-pmc

[Ed_McCarron]

Set your phaser on stu...

No, wait.  Set your multimeter on Ohms (resistance)

Check resistance from the two pins that are commoned to the other pin. 

Resistance should change as you cycle the pot.

[pmc]

Set your phaser on stu...

No, wait.  Set your multimeter on Ohms (resistance)

Check resistance from the two pins that are commoned to the other pin. 

Resistance should change as you cycle the pot.

Thanks Ed. Worked like a champ. The brake was like 200-ohms (if I got the scale right) and decreased to near zero as I applied pressure (turned shaft on the pot). The accelerator started with higher resistance, but worked similarly. I assume both are working correctly (as I suspected) and now I have either a wiring/solder problem or I have some sort of USB PCB prob. Or, of course, Windows could be messing with me as usual. 

Thanks for the help.

-pmc

[AceTKK]

Do you have the correct driver installed?  If you don't have one from the manufacturer, you can go to Control Panel > Game Controllers > Add to load a generic driver that might work.

-Ace-

[pmc]

Do you have the correct driver installed?  If you don't have one from the manufacturer, you can go to Control Panel > Game Controllers > Add to load a generic driver that might work.

Doesn't require a driver. It's a Thrustmaster Nascar Pro Digital 2. It comes with a mapper package which is nice for remapping buttons and controls on a per application basis. But there's no manufacturer supplied drivers. That's one reason why I'm so puzzled that the pedals don't work. I'm not sure what could even go wrong! Pretty sure I tested on another PC once and I got the same result. Everything else works and is visible in the Control Panel without the mapper software present. But pedals are ignored as if they are not connected.

An inspection of the wiring and PCP doesn't reveal anything obvious. My next move is to poke at it with a stick and see what happens...

Been playing Need for Speed Underground and Outrun but have been using the wheel paddles as digital accelerator/brake. Works OK.

BTW, I can't get Spy Hunter to work with a digital accelerator at all. Seems to ignore my key presses. Messed with the controls for a good 30-min to no avail. MAME 0.97. Anyone else have trouble with Spy Hunter?

-pmc

[AceTKK]

Everything requires a driver.  If the wheel is recognized w/out installing a seperate driver then Windows did it for you automatically.  The first thing I would try is going to the Game Controllers menu (see my post above) and adding the generic driver for two analog pedals.  If that doesn't work, try searching the Thrustmaster website for a driver.

-Ace-

[versapak]

First you want to smell it, and make sure it is not oregano, then you just roll it up...


Oh... Wait a minute...

You said A pot.





Move along folks... Nothing to see here.

[u_rebelscum]

...But pedals are ignored as if they are not connected.

Check if the wire between the pedals and the wheel works, and the connection is good.  Also, look in the driver/thrustmaster settings and see if it can see the pedals.  If not, the problem is the driver or physical.  If yes, check where the pedals are mapped to in the driver/thrustmaster panel settings, and make sure they aren't disabled or remapped to a different or digital input.

BTW, I can't get Spy Hunter to work with a digital accelerator at all. Seems to ignore my key presses. Messed with the controls for a good 30-min to no avail. MAME 0.97. Anyone else have trouble with Spy Hunter?

Spy hunter sucks with a digital pedal.  You need to be able to drive in high gear, but not max speed 24/7.  Speeking of which, make sure you're in low gear, and if you must use a digial input, map in mame the digital input to pedal decrease (which is for physical digital inputs), not pedal analog (for physical analog inputs).

[AmericanDemon]

First you want to smell it, and make sure it is not oregano, then you just roll it up...


Oh... Wait a minute...

You said A pot.





Move along folks... Nothing to see here.

Heh.  Dude, almost wrote the same.  Must be all those potentiometers that I smoked earlier testing amperage and a 240v lighter. 

[pmc]

Everything requires a driver.  If the wheel is recognized w/out installing a seperate driver then Windows did it for you automatically. 

That's what I meant. Thrustmaster does not provide a driver. A generic one is used by Windows. W2K device manager says that it's a "HID Compliant game device". The properties tab of the "gaming options" control panel shows a miniature photo realistic image of the wheel and pedals and registers a wheel turn or button press. The pedals are shown here, but the software does not respond to manipulations of the pedals.

Here's the write-up from Thrustmaster's web site:

No drivers are required for this device.

This device is fully compliant with the "Human Interface Device" specifications.

We have developed the device in such a way that it will be recognize under the Microsoft Operating systems (Windows 98 series, Me, 2000 and Windows XP) as an "HID compliant Game Device".

By simply connecting your Thrustmaster game controllers to the computer

[pmc]

The first thing I would try is going to the Game Controllers menu (see my post above) and adding the generic driver for two analog pedals.

[AceTKK]

Man, bummer.  I was hoping it was just a Windows problem.  Good luck and let us know once you've figured it out.

-Ace-

[pmc]

I plugged it into a MacOS 9.2 iBook and launched MacMAME 0.66. The wheel automagically shows up in MAME and everything works perfectly -- but the pedals are not present. Pisses me off because half the reason I got the wheel was for Spy Hunter and now I can't really play it.

I'm going after the USB PCB with a multimeter next... and then I'll see if I can eBay a replacement set of pedals...

-pmc

[pmc]

This may be a moot point now.

I spent and hour with a multimeter trying to understand the circuit and how it was connected. Then, to my horror, I realized that I was still plugged in to a running computer. While I'm not 100% positive at this point (I have to resolder one cable), I have a good feeling that I shorted the darn thing 10 ways to sunday. It's no longer a recognized device to the computer.

It might have been faster to smash it pieces with my fists. 

Anyway, I'll do some soldering tomorrow, and then test again before I go looking for a parts carcass or try to hack it into a 360-degree wheel. This sucks because I just finished mounting it to a new control panel. Ah well. Not the first time I wrecked a perfectly good device while trying to "fix" it.

-pmc

[pmc]

USB PCBs are more resiliant than I thought. After patching it back to where I started, the damn thing was back to working! Amazing considering the man-handling I gave it. Not only that, but the pedals actually worked as long as I wiggled the PS/2 connection just right. Jackpot! I have a connector problem. 1-step backwards, 2-steps forward. Like usual I guess.

The pedals have four wires coming from them (2 from each pot) and terminate in a male PS/2 mini-DIN 6-pin connector. If you want to use the pedals, you connect that to a female PS/2 connector that sticks out of the wheel housing. The flaky connection appeared to be at the molded stress reliever on the female side of the connection (no suprise actually).

So I cut out both the PS/2 connectors figuring I'd just solder it all together. I'll splice quick disconnects or something like that after I get the situation stable.

That's when it got ugly again. The female mini-DIN has 6-wires and just before it gets to the PCB, some of them splice into the USB wires coming the the PC. It's not easy to tell what's what from there. But no matter... all I gotta do is splice 4 wires to 6. OK, so I tone out each wire's associated pin, and then I connect the plugs together and tone out to the wire(s) on the other side of the plug. I twisted the wires together and tested. Nothing. I worked on it for an hour or more, testing and trying. Nothing. Nothing. and Nothing. Wheel never stopped working, but pedals never started.

I don't know where I went wrong, but I'm hoping I took another step back to prepare for 2-steps forward.

Any gotchas with those PS/2 style connectors? ground connected to shield or something strange like that? I have a pin that tones to multiple wires which seems odd/incorrect. But otherwise, how do I know which wires to connect where? Anyway, now that I know that the device is resiliant no matter what I try, I'll keep whacking at it. Thanks for listening. It's therapeutic.

-pmc

[M3talhead]

....inhale

[pmc]

....inhale

I think it's the coffee that does it.

[pmc]

Fixed it. Spy Hunter works great with an analog accelerator!

The PS/2 connector was not wired in a standard fashion. I had a couple 3-wire connections that were not obvious. Once trial and error got me the correct connections, I soldered everything down and shrink-tubed my work. Solid as a rock now.

I only wish the 270 wheel worked with more MAME driving games and/or I could hook it up the Dreamcast to play Daytona USA, Sega GT and the like.

-pmc