I'd like to find Digikey ordering numbers for these guys, to order replacements, but my searches there aren't working, nothing is coming up which looks anything like what I've got here. Anyone know how to ID these? Photos attached.

These are parts from a joystick, Thrustmaster T-Flight HOTAS 4 model. The pots are for X/Y axis and the rudder rotation axis, and the switches are for the 4-way thumb-hatswitch.

Switches are temporary pushbuttons with a sort of a "click" to them when they are pressed. Potentiometers have a limited rotation travel range of about 270 degrees total, though I don't have an easy way to measure that accurately to be sure. I'm hoping that the printed codes on there are some kind of a clue to their detailed specs.

Thanks for any advice or help you can offer!

You may be interested in this repair service.

https://www.ebay.ca/itm/233195609114

I have used the bn880 repair service for a different electronic product and was entirely satisfied with the turnaround time, the pricing and the repairs. He works through ebay for the repair billing and initial communications.

I do not know if he would be willing to just sell the repair parts. Possible?

These switches are similar, but not identical:

https://www.digikey.ca/en/products/detail/judco-manufacturing-inc/50-0014-00/307996
https://www.digikey.ca/en/products/detail/cw-industries/GPTS203212B/3190592

On Digikey, I searched for Switches -> Pushbutton Switches and then filtered with Mounting Type (Through Hole; Right Angle) and Circuit (SPST).

For the pots, more info would be required to find a suitable match. Eg. the overall resistance (10K-Ohm?), whether it is linear (most likely) or logarithmic.

With that info, a Digikey search should be possible. They don't carry everything though.

For the pot, the B104 tells you it's a linear taper 100K.

Here's a similar pot that would probably work:

https://www.digikey.com/en/products/deta...pQFgBkACEAXQF8g

This part number is for the shaft with the flat, although the picture doesn't show that.

Mark, thanks for the switch links. Theoretically any momentary SPST switch will work as long as it's the same dimensions, so that is very useful.

I dismantled my troublesome switch under magnification, and it was a normal dome switch on the inside. It looked like it was manufactured with poor QC, and there was a lot of blackness on the dome and the contact points, as if the black plastic had outgassed or "bled" during the manufacturing. Cleaning it with isopropyl and re-assembling has made it work fine again, but I intend to order more replacement switches just so I have more on-hand so that future repairs are easier.

Larry, thanks so much for the ID of the pot. I was indeed hoping that the numbers printed on it would indicate its specifications. Where can I find a reference source for how to read those identification numbers? Some googling gets me a lot of links for guitar amps, and the larger pots in those amps seem to use different types of coding numbers. For example, though I see that "B" means linear taper, I don't see how "104" indicates 100K?

Thanks so much for the link, it will get me started on the right track. Though the particular pot that you linked doesn't look like the exact dimensions and shaft, I will start there and keep looking to find one with correct shaft/dimensions. You said that the picture doesn't show the keyed shaft, despite the part number being correct for a keyed shaft. I'm also concerned with the threaded neck, which might not fit the place where the joystick accepts the part. I'll keep looking to be sure I get the right part.

In the meantime, squirting some electronics solvent and isopropyl into the pot has gotten it working normally again. I will still find and order more replacements for the future: Cleaning only works on these things for a limited amount of time.

K447, thanks so much for the link to that repair service. I will check them out.

104 = 10 with four extra zeros appended = 100000.

That alcohol will clean the pot but depraves it of any lubricant.

I use this stuff:

https://www.learchem.com/products/acf-50.html

I soak my new pots in it as they tend to wind up in corrosive environments. This stuff protects them and adds a lubricant layer much better than what they come with.

Yeah, what Mark said. Also, an A prefix is "Audio taper" and B is "Linear taper".

Thanks so much, Larry and Mark, I'll see about finding some of that pot lubricant. Good information.

I have found these, based on this reddit thread.

- CTS Electronic model 251B12T104A2NB
- These have a 12mm shaft though the original has only a 7mm shaft. [EDIT: I measured the original wrong, they actually both have the same shaft length]
- However their "Throw", the lock-to-lock sensitivity, is a hair "short" of the actual joystick extremes, compared to the original, when viewed in the joystick control panel software. One might be able to overcome this by setting the joystick sensitivity up a hair in the game.

I've soldered a couple in, and I'm going to try them out in-game when I get a chance.

The issue is that when I plug it into a joystick testing program, the new pots are kind of "off center", I guess is the correct way to describe it.

The joystick decides what "center" is when you first plug it in. This is the "0" point on the potentiometer. If the joystick is "relaxed" when you plug it in (its springs have it sitting at its center point) then theoretically you should have full range of values in the computer readout. But that's not what's happening. When I plug it into the computer, it shows these values with the new pots:

X-axis, stick full leftwards: -32768
X-axis, stick full rightwards: 30711 (or a bit higher if I push really hard)
Y-axis, stick full backwards: 32767
Y-axis, stick full forwards: -31226 (or a bit higher if I push really hard)

Whereas the original potentiometers give me full range -32768 through 32767 for both axes.

Seems "OK" in-game so I'm not "too" worried about it. I just wonder if I'm not getting my full turning rate in my X-Wing when I'm banking right or diving. The way this thing is constructed, there's no way to "adjust" the pot positions, it's all plastic snap-in-place stuff and the shafts of the pots are D-keyed.

The pots you gots have a 10% tolerance on them. I wonder if the original pots had a tighter tolerance, or if the joystick mfg just tested each pot and used the ones that fell in range.

Indeed I had the same thought. I'm looking but I can't find pots with tighter tolerance. The datasheet for the CTS ones that I linked, says that 10% is their best version, their others are 20% and 30%. Searching for pots with the same physical dimensions keeps leading me back to that CTS one.

It's entirely possible the joystick mfg cherry-picked the pots, or had the pot mfg do it for them.

I had to do this once when working at a thin-film hybrid shop making microwave amplifiers. The amps bought to spec were so expensive that we'd just buy hundreds of lower spec amps and test each one. I was just a pup out of school back then. Now I can't imagine that the company actually saved any money doing this.

I usually have a couple hundred 10K 10% pots in stock, so just for fun I tested a few. I had assumed that they would be ±5%, but it seems they are more like ±10%, or +5% -10% in my sample.

It also occurs to me that all the pots, when run to their limits, are all 0 ohm from wiper to that terminal. Does the joystick limit the pot to a portion of its travel, or does it go to the limits?

Excellent question. The joystick travel, lock to lock, is actually a very small portion of the overall travel range of the potentiometer. I haven't got an easy way to measure it, but it seems like it's probably something like 45-50 degrees worth of total travel. So the pots in the joystick are only using a small pie slice of the total capabilities of the pot. So it would make sense that if the tolerance of the pot varied by as much as 10 percent, then I'd indeed expect it to make a visible difference like the one I'm seeing.

If I were the one designing the thing, I wouldn't use cherry picking to get homogeneity. I'd fix it in the electronics or the joystick firmware. For example, via trim pots on the circuit board (I didn't see any but I'll double check), or write the firmware so that it corrected for pot variance over time.

I briefly tried adding a second pot to act as a trim pot, but it made things worse and was too fiddly to be able to make a good adjustment anyway.

I think it's probably actually OK in the game, and I don't really need to do anything to correct this, most of this is just an interesting tech exercise for me.

It's not uncommon for the mechanical range of travel and the electrical range of travel of a potentiometer to vary significantly. For example, in the 251B12T104A2NB model referenced, the mechanical range of travel is specified as 180 degrees, whereas the electrical range of travel (sometimes called the effective electrical angle) is 50 degrees.

The datasheet shows how to decode the part number to find the electrical range of travel, indicated by the number in the third-to-last position of the model number, in this case 2. However, the datasheet on the Mouser site seems incomplete and doesn't have 2 as a valid value in that position. Digikey have a more complete/up-to-date datasheet here: https://www.digikey.com/htmldatasheets/production/2758000/0/0/1/251-series-datasheet.html

In positions outside of the electrical range of travel you'll generally not see any change in resistance, as the wiper is likely in contact with one of the terminals.

Thanks so much for all this information, everyone.

Interesting that Digikey has a more recent datasheet than Mouser, yet Mouser carries the part in stock but Digikey doesn't.

I buy most of my parts from Mouser. Occasionally I'll use Digikey, then Newark. For more industrial electrical parts, I use Allied, then Grainger.

Some stuff is getting hard to get. I ordered 500 bulk transformers from Mouser to be drop shipped from the "factory", but they were backordered for months. I finally bought 25 in retail boxes as I had run out, and the 500 arrived the day after with no notification. Well, 2 days later I did get an email saying they had been shipped...