Logitech Pots

[Clive Loynes]

I have been searching to find some decent replacements for the manky pots used in my G25 pedals and have come up with a couple of solutions.

Firstly these: http://www.ebay.co.uk/itm/370852871606?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Which appear to be a direct replacement but at £22 each it gets a bit steep for three, although there is the option to make them an offer.

I have also found a cheaper solution but they will take more "fitting" but will provide a good long-life cermet pot if I can do it.

I'll let you know.

[Clive Loynes]

[Wiltshire Tony]

Cannot see the pictures?

[Clive Loynes]

Cannot see the pictures?

Me neither but I'm fighting it.  ;-)

As you can see, I have made use of some parts of the manky old pots to provide mounting and connection compatibility.

The black plastic bit in the last picture is a bit mangled because I ended up cutting the centre hole in the wrong place, after hitting the E-Stop, but it is all held in the right place by the hole in the steel plate anyway.

I used the black plastic bit so that I didn't have to do anything to the steel chassis. 

These pots come without a flat on the shaft so I had to machine that on too.

Down side of using the black plastic bit is that the length of the shaft is marginal when it comes to refitting the retaining clip.  But I made the flat a good fit so it may not matter.

[Clive Loynes]

Well that's me out of action for the foreseeable future.

Everything is back together and none of the pedals will work!  Not even registering on the Wingman utility.

They are 10k pots, as were the ones that they replaced, there is a nominal 5v being supplied to either end and they appear to be functioning as a voltage divider.

Looks like it is all heading for the bin!

[phspok]

Been a while since I moved my pots around, but does it use one end to wiper?
if you've accidentally wired to both ends then pot turn will do nothing useful
Appologies if that insults you intelligence 

[Clive Loynes]

The pots have 5v across them and the wiper moves over a limited arc at the middle of its travel.  So the wiper sees a proportion of the 5v, about 2v at zero travel.

I took pictures of the original wiring to make sure that I ended up with the same circuit.  Top and bottom connectors on all of the pots are red and black, whilst the signal wires are white, orange and something else that I can't remember. 

I expected to have to reverse the controls but I'm stumped as to why they don't work at all!

[Wiltshire Tony]

There's probably a clip on You Tube of someone doing it correctly

[phspok]

I am Southport Saturday if you want to compare against mine.

[Clive Loynes]

I am Southport Saturday if you want to compare against mine.

Thanks Matt but for now I have thrown everything in the corner of the room until such time that I can face the eleventy million screws again!

[Clive Loynes]

I suspect that I haven't machined the flat on the shaft such that the pot uses exactly the centre section of the track.

Thus the voltage signals may be out of range.

I shall test with some standard pedals to make sure that the A-D board in the wheel is still healthy before doing anything else.

I might try one of the Leo Bodnar USB cables, if all else fails, as surely that can be configured to use any voltage values?

Thanks again for the offer Matt but we are out on Saturday.  ;-(

[Clive Loynes]

Think that I may have found out what the problem is.

The original pots are 10K ohm but they sweep through this in 70 degrees of travel.  So the analogue voltage signal will start somewhere near 0V and end up somewhere near 5V, or vice versa.

My voltage signal goes from about 2V to about 3V and so the A/D board inside the wheel is rejecting the starting point and just not recognising the pedals.

I'm hoping that either a Leo Bodnar adapter or something from Basherboards my be able to take my puny 1V variation in signal and turn it into enough digits to give me a decent pedal response.   

[NickyIckx]

Hi Clive,

I am absolutely not an expert on electronics. In fact I have no knowledge at all on that really.

But I am pretty sure its not a matter of matching exactly amount of Volt like you say, as only the differences between start and stop are measured.

But I could be wrong on that and these G25 circuitboard indeed only works in that Volt areas you mentioned.

However here some thoughts/idears:

Looks like your new potentiometers do match 10k +-10% ,like the original G25 pedals pots have.
But if the originlas are linear or non-linear ( no idear what that really is ) could be important to know. To be on save side the new pots may should match these parameter as well.

Antoher thing important to know, is the working range of the potentiometers. Some do have a  dead zone on their travel range. Mostly those who come without an mechanical start and stop.
However , to check that I did used the tiny programm called DIView.
It makes the movement of pots visible and allows calibration/configuration.

http://www.leobodnar.com/shop/index.php?main_page=page&id=12



Dunno if that helps you, as your pedals run via G25 circuitboard, if I understood right.
At least your wheels axis movement should be displayed.
If your pedals arent recognized by diwiew then , even if you did move the pots axis by hand , to got free from the limitted travel way given by the gearing of the G25 pedal construction, I am clueless.
But if, then you are able to figure out the right position of  how each axis has to been mounted to the gearing of the pedals. ( working range of potentiometers ).

I never did run pedals via G25 circuitboard. ( never did have an G25 wheel ).
I always used LeoBodnar USB chip stuff to run my wheels and pedals.

Actually I run G25 pedals wired to that kinda chip.
It could be that these Bodnar chip is more forgiven than G25 circuitboard, if pots are on that dont match exactly the originals in all therms. I dont know....


So in case your new pots could not go to work via G25 wheel,  for sure its an good alternative to run for an LeoBodnar BUO836 12bit joystick controller.

Good luck and do not hesitate to ask more.


Btw. If I am lucky, today my new Clubsport V3 pedals do arrive. Wonder if I can get used to that hall sensor magnetic stuff so....

kindly regards
Nicky

[Clive Loynes]

Thanks for the response Nicky.

I believe the original pots to be linear but it's the 70 degree bit that is the problem.

By my calculations, the original pots will give a voltage signal that varies from 0.9v to 4.1v whereas my pots will only give me, say, 2.17v to 2.83v.

I don't know how adaptable the Leo Bodnar system is but it should be possible to convert it to digital with something! 

I suppose that I could just use the analogue signal and stuff it in the game port to start with. 

[picnic]

Even if you got your new pots working I'd have thought the lower voltage range would result in lower resolution. Are you seeing this limited range because once mounted the pots have a reduced physical travel? If unrestricted you should see 0 to +5V on the wiper as you move it from one extreme to the other.