!NOT for Thrustmaster T3PM and T-LCM, shoot, off you go, magnets how do they work?!
I replaced potentiometers on my thrustmaster pedals (T3PA) with non-original potentiometers (cheapest, lowest quality ones I could find locally as per Thrustmaster standards). I want to share how.
Why post? There are a couple of post online about potentiometers on thrustmaster (TM from now on) pedals dying, some posts about specific model of potentiometers used in TM pedals, some about ordering replacement potentiometers from TM themselves, and frankly speaking, these post all are not very good, they skip important info, or have a bunch of half-truths. If you are new to repair and DIY it can be very confusing, so hopefully I can help.
Side-note, yes, all TM budget pedals are terrible, yes, there are better options, we all know this. But working terrible pedals are better then non-working ones (not by much though in case of TM).
I have a T3PA set I no longer use, with worn out potentiometer (accelerator pot had jittery input, fixed with cleaning 2 or 3 times, then stop having input in TM control panel at all), that I have decided to fix. Should be easy, right? Step one, go to TM website order replacement, done, right? No, TM does not offer replacement potentiometers on their website, some people have contacted them directly and it seems to be possible to get potentiometers in some parts of the world, so maybe, but most likely not a option. Then order potentiometers elsewhere, right, how hard can that be, pots are very common parts, easy? Well, if you are not an electrician or avid DIYer, it is not straight forward, and post with half-truths or flat-out wrong information can mislead, so I am here to help. There is a lot though, lets go step by step.
Step 1: Get info from original potentiometer.
B25K60 is the only marking on mine, and it tells us... nothing. Why, because potentiometers have many variations, and usually the outer case is shared by many of these variants. Which means that manufacturer has to make model specific case or mark them afterwards, that is why cheap pots usually do not have full model name on them. Best case scenario, a model name, but under that name might be hundreds of specific variations (resistance, taper, shaft, mounting, connection, we will get there, do not worry). TM also makes flight sim pedals and in those are Fanrui RK166N (dongguan fanrui electronics) potentiometers, looking at Fanrui products there is a chance our B25K60 is a Fanrui of some sorts. But we do not have full model name, their website is terrible, and I am not ordering 2 to 3 times from alibaba or aliexpress till I find direct replacement. So we need to find analog part locally (Europe), but to do that we have to understand how everything works.
Step 2: Physical dimensions.
The B25K60 has a 6mm diameter shaft that is about 13mm in length (~19mm total including threads). Shaft has a ground flat portion, these type of shaft are called D shafts or flat shaft. Shaft length is not that crucial, a shorter will work as well. Most 6mm diameter shaft will have the same mounting nut (10mm). Then there is the connection, through pins or solder lugs will work.
Step 3: Electric bits.
Total Resistance
To understands values we care about, we must understand how potentiometer pedals work in the first place. Potentiometers have 2 main uses, first as a variable resistor (only 2 of the 3 terminals are used), second as a voltage divider (all 3 terminals are used). Sim pedals use voltage divider arrangement. What that means is that each pedal has 3 wires (Ground, Supplied voltage, and Signal which is our V(out)). Here is the formula for voltage divider V(out)=V(in)*(R2/(R1+R2)). Why I bring it up, many the post online talk about the total resistance (R1+R2) of potentiometer as the thing that gives the signal its value, but the signal (V(out)) is determined by the ratio between the resistance you set and the total resistance of the potentiometer. Meaning, you have a voltage divider circuit, lets say you have 10V, you want 5V, both a 10 ohm potentiometer and a 10000000 ohm (10 Mohm) potentiometer set half way (5 ohm or 5000000 ohm) will give you 5V out, theoretically. Meaning V(out) our signal (gas, brake, clutch) is determined purely by how much you "rotate" the potentiometer, not it's total resistance. Then what does total resistance change, I=V/R total current in circuit. Our B25K60 measures at 13.25kohm across first and third terminal, meaning we need something around 10kohm rating. If we go higher (10kohm<x), then less current will flow and at some point because of voltage drop (and other losses) wheelbase will not see any signal or a insufficient one. If we go lower (x<10kohm), then more current will flow and the measuring circuit in wheelbase has a limit, and at some point something will fry, or pop, or smoke. I do not know the limits, stick around 10kohm and you will be fine. (Most potentiometers go in steps 1k, 2k, 5k, 10k, 22k, that is why 10k is chosen).
Taper
Taper is simply how that resistance ramps up, if 10% of total rotation gives you 10% of total resistance, and 20=20, 30=30, and so on, then it is called a linear taper. The two most common tapers are linear and logarithmic (also called audio taper). Here comes first confusing bit many logarithmic tapers actually look exponential if graph, why, well I am not an electrician, or an electrical engineer lets just assume there is a good reason. So how to know what are you getting, most manufacturers offer some technical data sheets that have model name decoder tables and actual graphs of said tapers. There are many other tapers, but they will range from harder to a lot harder to source and get, since linear and logarithmic serve DIYers, most repair needs and so on. And here comes the second confusing bit, some posts talk about "effective rotation degrees/range", which is not helpful because it is not an actual term to my knowledge. Since pots are described with max lock-to-lock rotation (usually ~300º) and everything else is taper (taper graph).
So our B25K60, it has a max lock-to-lock of about 300 degrees, and with multi-meter, you can figure out the taper, which is an extreme exponential with a flat sections (minimum resistance and maximum resistance) at both ends. In simple words it goes like this: min, min, min, min, min, quick ramp-up, max, max, max, max, max resistance as you turn it.
And that is not good for us at all. This is one of those other taper, and no, I do not know the name of it. Sourcing it could be hard, and even if you find one that fits physical dimensions and has a similar taper, if the taper is off by even a little bit you could end up with noticeable dead-zones in pedals.
What you need
So now you have all the info for a fix, a potentiometers with a 6mm diameter D shaft (length 13mm), that has a 300º max lock-to-lock rotation, with through pin mounting, and a very exponential taper, that has a flat sections at both rotation ends, and a total resistance of ~13kohm (10kohm will also do).
How I fixed my pedals.
My local online electronics shop had something similar for the taper (still not a guarantee will work) but delivery time was too long and the price was ~10€ for a single pot, and the shaft did not mach (need D shaft, had knurled shaft), and if I have to guess the TM paid 0.5 - 1.5 euros per pot, most likely well below 1€, and I do not think there is value in spending 10€ for single potentiometer, since pedals are terrible to begin with, and if you want to spend more, then do a hall-effect sensor conversion or a load-cell, or buy a better pedal set. Cheap fix for cheap pedals is the name of the game here.
So lets use TM software to our advantage. TM tells you to NOT press any of the pedals while plugging them in our wheelbases, why, well each pedal has a signal wire, and when you plug in the pedals (for first time after wheelbase has been connected) whatever the wheelbase sees on that signal wire is assumed to be the zero value. This is TM pedal self-calibration. Form the factory mine were configured as follows 0% pedal input = 0V at the signal wire, and as you give pedal input the voltage on signal wire rises. But you can re-assemble them were 0%=lets say 1V, and the voltage rises from there, I discovered this when cleaning pedals for the first time, because I assembled one of the pedals wrong.
I bought R16148-1A-2-A10K from SR PASSIVES cheap terrible pots for cheap terrible pedals, as TM intended (Cheap pots vary a bit, if can order some extra to match them more closely). Downside number one, shaft is wrong, I will have to drill out the plastic gears from D shape to a circle. Downside number two is the tricky bit, these pots have a nice smooth exponential rise in resistance as I turn them, if I mount them so that at 0% pedal input there is 0V at the signal, at 100% pressed pedal the TM control panel will show ~30% input, why, because TM software is setup for that sharp stock taper, and these just do not ramp-up quick enough. But if I position (meaning, where in their rotation pots are used, 0-300º is max to max, but the pedals will rotate them ~70º, so 100-170º or maybe 200-270º is what I mean by positioning) them were at 100% pressed pedal the pots are quite close to the max resistance (almost fully turned), then the ramp-up is quick enough. This takes some time, if positioned wrong the pedal will turn the pot pasted its max rotation and damage it, there must be a bit of a buffer so this does not happen. And is not good for them anyway but it works. And that is how I fixed my T3PA while my main pedals were offline for couple of months. They worked for 2-3 months without issues, and I put them away in working condition. I did however notice that maybe there is a bit of extra dead-zone towards pedal max travel range, it is not noticeable in game or at a quick sweet in control panel, but when in control panel and pressing very slowly then at 97% pressed pedal TM control panel indicates 100%, but like I said not at all noticeable in game.
So I will add an excel spreadsheet with more technical info. And make your own decisions, I was willing to modify the plastic gears, you might not be. Maybe find some 10K logarithmic pots with correct shaft, I did not, because it was faster for me this way.
Hope it helps, I am not responsible if you brake something.
I replaced potentiometers on my thrustmaster pedals (T3PA) with non-original potentiometers (cheapest, lowest quality ones I could find locally as per Thrustmaster standards). I want to share how.
Why post? There are a couple of post online about potentiometers on thrustmaster (TM from now on) pedals dying, some posts about specific model of potentiometers used in TM pedals, some about ordering replacement potentiometers from TM themselves, and frankly speaking, these post all are not very good, they skip important info, or have a bunch of half-truths. If you are new to repair and DIY it can be very confusing, so hopefully I can help.
Side-note, yes, all TM budget pedals are terrible, yes, there are better options, we all know this. But working terrible pedals are better then non-working ones (not by much though in case of TM).
I have a T3PA set I no longer use, with worn out potentiometer (accelerator pot had jittery input, fixed with cleaning 2 or 3 times, then stop having input in TM control panel at all), that I have decided to fix. Should be easy, right? Step one, go to TM website order replacement, done, right? No, TM does not offer replacement potentiometers on their website, some people have contacted them directly and it seems to be possible to get potentiometers in some parts of the world, so maybe, but most likely not a option. Then order potentiometers elsewhere, right, how hard can that be, pots are very common parts, easy? Well, if you are not an electrician or avid DIYer, it is not straight forward, and post with half-truths or flat-out wrong information can mislead, so I am here to help. There is a lot though, lets go step by step.
Step 1: Get info from original potentiometer.
B25K60 is the only marking on mine, and it tells us... nothing. Why, because potentiometers have many variations, and usually the outer case is shared by many of these variants. Which means that manufacturer has to make model specific case or mark them afterwards, that is why cheap pots usually do not have full model name on them. Best case scenario, a model name, but under that name might be hundreds of specific variations (resistance, taper, shaft, mounting, connection, we will get there, do not worry). TM also makes flight sim pedals and in those are Fanrui RK166N (dongguan fanrui electronics) potentiometers, looking at Fanrui products there is a chance our B25K60 is a Fanrui of some sorts. But we do not have full model name, their website is terrible, and I am not ordering 2 to 3 times from alibaba or aliexpress till I find direct replacement. So we need to find analog part locally (Europe), but to do that we have to understand how everything works.
Step 2: Physical dimensions.
The B25K60 has a 6mm diameter shaft that is about 13mm in length (~19mm total including threads). Shaft has a ground flat portion, these type of shaft are called D shafts or flat shaft. Shaft length is not that crucial, a shorter will work as well. Most 6mm diameter shaft will have the same mounting nut (10mm). Then there is the connection, through pins or solder lugs will work.
Step 3: Electric bits.
Total Resistance
To understands values we care about, we must understand how potentiometer pedals work in the first place. Potentiometers have 2 main uses, first as a variable resistor (only 2 of the 3 terminals are used), second as a voltage divider (all 3 terminals are used). Sim pedals use voltage divider arrangement. What that means is that each pedal has 3 wires (Ground, Supplied voltage, and Signal which is our V(out)). Here is the formula for voltage divider V(out)=V(in)*(R2/(R1+R2)). Why I bring it up, many the post online talk about the total resistance (R1+R2) of potentiometer as the thing that gives the signal its value, but the signal (V(out)) is determined by the ratio between the resistance you set and the total resistance of the potentiometer. Meaning, you have a voltage divider circuit, lets say you have 10V, you want 5V, both a 10 ohm potentiometer and a 10000000 ohm (10 Mohm) potentiometer set half way (5 ohm or 5000000 ohm) will give you 5V out, theoretically. Meaning V(out) our signal (gas, brake, clutch) is determined purely by how much you "rotate" the potentiometer, not it's total resistance. Then what does total resistance change, I=V/R total current in circuit. Our B25K60 measures at 13.25kohm across first and third terminal, meaning we need something around 10kohm rating. If we go higher (10kohm<x), then less current will flow and at some point because of voltage drop (and other losses) wheelbase will not see any signal or a insufficient one. If we go lower (x<10kohm), then more current will flow and the measuring circuit in wheelbase has a limit, and at some point something will fry, or pop, or smoke. I do not know the limits, stick around 10kohm and you will be fine. (Most potentiometers go in steps 1k, 2k, 5k, 10k, 22k, that is why 10k is chosen).
Taper
Taper is simply how that resistance ramps up, if 10% of total rotation gives you 10% of total resistance, and 20=20, 30=30, and so on, then it is called a linear taper. The two most common tapers are linear and logarithmic (also called audio taper). Here comes first confusing bit many logarithmic tapers actually look exponential if graph, why, well I am not an electrician, or an electrical engineer lets just assume there is a good reason. So how to know what are you getting, most manufacturers offer some technical data sheets that have model name decoder tables and actual graphs of said tapers. There are many other tapers, but they will range from harder to a lot harder to source and get, since linear and logarithmic serve DIYers, most repair needs and so on. And here comes the second confusing bit, some posts talk about "effective rotation degrees/range", which is not helpful because it is not an actual term to my knowledge. Since pots are described with max lock-to-lock rotation (usually ~300º) and everything else is taper (taper graph).
So our B25K60, it has a max lock-to-lock of about 300 degrees, and with multi-meter, you can figure out the taper, which is an extreme exponential with a flat sections (minimum resistance and maximum resistance) at both ends. In simple words it goes like this: min, min, min, min, min, quick ramp-up, max, max, max, max, max resistance as you turn it.
And that is not good for us at all. This is one of those other taper, and no, I do not know the name of it. Sourcing it could be hard, and even if you find one that fits physical dimensions and has a similar taper, if the taper is off by even a little bit you could end up with noticeable dead-zones in pedals.
What you need
So now you have all the info for a fix, a potentiometers with a 6mm diameter D shaft (length 13mm), that has a 300º max lock-to-lock rotation, with through pin mounting, and a very exponential taper, that has a flat sections at both rotation ends, and a total resistance of ~13kohm (10kohm will also do).
How I fixed my pedals.
My local online electronics shop had something similar for the taper (still not a guarantee will work) but delivery time was too long and the price was ~10€ for a single pot, and the shaft did not mach (need D shaft, had knurled shaft), and if I have to guess the TM paid 0.5 - 1.5 euros per pot, most likely well below 1€, and I do not think there is value in spending 10€ for single potentiometer, since pedals are terrible to begin with, and if you want to spend more, then do a hall-effect sensor conversion or a load-cell, or buy a better pedal set. Cheap fix for cheap pedals is the name of the game here.
So lets use TM software to our advantage. TM tells you to NOT press any of the pedals while plugging them in our wheelbases, why, well each pedal has a signal wire, and when you plug in the pedals (for first time after wheelbase has been connected) whatever the wheelbase sees on that signal wire is assumed to be the zero value. This is TM pedal self-calibration. Form the factory mine were configured as follows 0% pedal input = 0V at the signal wire, and as you give pedal input the voltage on signal wire rises. But you can re-assemble them were 0%=lets say 1V, and the voltage rises from there, I discovered this when cleaning pedals for the first time, because I assembled one of the pedals wrong.
I bought R16148-1A-2-A10K from SR PASSIVES cheap terrible pots for cheap terrible pedals, as TM intended (Cheap pots vary a bit, if can order some extra to match them more closely). Downside number one, shaft is wrong, I will have to drill out the plastic gears from D shape to a circle. Downside number two is the tricky bit, these pots have a nice smooth exponential rise in resistance as I turn them, if I mount them so that at 0% pedal input there is 0V at the signal, at 100% pressed pedal the TM control panel will show ~30% input, why, because TM software is setup for that sharp stock taper, and these just do not ramp-up quick enough. But if I position (meaning, where in their rotation pots are used, 0-300º is max to max, but the pedals will rotate them ~70º, so 100-170º or maybe 200-270º is what I mean by positioning) them were at 100% pressed pedal the pots are quite close to the max resistance (almost fully turned), then the ramp-up is quick enough. This takes some time, if positioned wrong the pedal will turn the pot pasted its max rotation and damage it, there must be a bit of a buffer so this does not happen. And is not good for them anyway but it works. And that is how I fixed my T3PA while my main pedals were offline for couple of months. They worked for 2-3 months without issues, and I put them away in working condition. I did however notice that maybe there is a bit of extra dead-zone towards pedal max travel range, it is not noticeable in game or at a quick sweet in control panel, but when in control panel and pressing very slowly then at 97% pressed pedal TM control panel indicates 100%, but like I said not at all noticeable in game.
So I will add an excel spreadsheet with more technical info. And make your own decisions, I was willing to modify the plastic gears, you might not be. Maybe find some 10K logarithmic pots with correct shaft, I did not, because it was faster for me this way.
Hope it helps, I am not responsible if you brake something.
