Help needed with potmeters

[ngabor]

Hi,

 

First off I am far form expert in electronics, so keep that in mind. Thanks.

 

I made a Frankenstein joystick (with extention) form a Thrustmaster TOPGUN and a MSFFB2. Then I decided that I will make a throttle form the leftover, which I did.

I am now almost complete, but just before finish the thurstmaster potmeters died (They were working initially).

I took them apart, cleaned, and tested with multimeter.

I found out that the connection between the legs and the circuit are only working when hot from soldering. If it cools down the connections are lost.

I tried to add new soldering to each side, but it didn't help.

 

I know I should ditch the foulty potmeters, but the other parts are all designed arount these bastards, so I am really desperate to repair them.

 

Please help, if possible.

 

Thanks.

[marcost]

Unfortunately, it's quite easy to damage pots by applying heat for too long when soldering but here's some suggestions...

 

Try cleaning all components with contact cleaner.

 

Have you made sure that the wipers are making good contact with the black bands? If not, bend the wipers up a little so there is more contact. The wipers are the silver blades that look like forks at the end.

 

Try lightly scraping/sanding the black band near the solder point. This might expose the conductive material better. Then solder this point up to the main solder point. 

 

Alternatively, most pots have a serial code on the outer case which can help you find a replacement.

 

Good luck!

 

M

[Sokol1]

Pot's are cheap, buy a new, depends on your USB controller, 10 to 50K, type B (Liner output, what is not related with slide pot or circular form).

 

Since you need "joystick potentiometer", get the models used in CH controllers, available in Digikey:

 

https://www.digikey.com/product-detail/en/ch-products/REPPOT604/1040-1164-ND/9490875

 

See bellow other models and even the plastic lever for pot used in their Quadrant.

 

* "Joystick potentiomter" differ from normal pots find in stores in "effective electric angle" of their resistive track.

Normal pot have 270/370º of "effective electric angle".

 

Since joystick/throttle/pedals don't move all this angles, their resistive trck is set for smaller  "effective electric angle", generally between 30 - 60º.

This type of pot' is rarely available in electronic stores, since has few use other than in josyticks/gamepades, R/C controllers.

 

As marcost say, when soldering pot' terminals use a heat dissipation clip, since heat can damage their tracks.

 

https://www.amazon.com/Heat-Sink-Solder-Aid-Kit/dp/B00LW6RMC0

[ngabor]

marcost:

 

Thanks. Now at least I know how I damaged it. I will handel pots more carefully in the future.

The wipers are fine. I testet the plain circuit (without the wipers) by connecting the two endpoints.

 

"Try lightly scraping/sanding the black band near the solder point. This might expose the conductive material better. Then solder this point up to the main solder point."

I will definetly try this. Fingers crossed...

 

Sokol1:

Fortunately I have collected some old gameport sticks from a local secondhand market for pennys, then I took the useful parts out of them so I have some spare joystick pots (and wires, buttons, springs) on hand.

PLan B is to use them if I cant repair those above.

That heat dissipation clip you mentioned, is it form some special low heatresistant material or can I use a simple metal plier instead?

 

Thanks!

 

[Sokol1]

This heat dissipation clip seems made in aluminium, their  objective is absorve heat beyond solder point, avoiding reach other components.

You can improvise one.

 

BTW - About "joy' pot", for things like trim wheel's 270/300º normal pot's is desirable, since give you more course, even better if you add a 3:1 gear.

Available 10:1 models (10 turn pot) result too slow.

 

[ngabor]

Thanks for all the help lads!

I managed to repair my pots! I struggled a lot trying to repair the connection by soldering, then I got enlightened and grabbed my pencil! Some graphite coating did the trick!

Finally I finished the throttel.

Here are some pictures:

 

Only one problem left:

The red lever is very very noisy, practically unusable. But the pot is fine. Can it be interference from the other cabels? Should I shield them somehow? It's input and ground is coming from the other pot, the wiper is standalone of course (just as it was originally).

 

BTW the throttle lever and all the buttons are working flawlessly.

[Sokol1]

Sometimes you test only the pot, turning pole axis with hands and work OK.

Install the lever an noise spark, is because the lever are forcing the pot' pole axis, making wipers inside pot loose contact of tracks.

 

BTW - Nice Gashebel.  

Edited August 6, 2020 by Sokol1