Buttons activating by touching a wire

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Discussion Overview

The discussion revolves around an issue encountered while modifying a gamepad to create an arcade controller. The problem involves unintended button activation when certain buttons are pressed, particularly when the user's hand is near or touching the solder joint of one button. Participants explore potential causes and solutions related to electrical shielding and circuit integrity.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Brian describes the issue of the left button triggering unexpectedly when the down button is pressed, particularly when touching the solder joint.
  • One participant suggests that high impedance input might be a factor in the problem.
  • Another participant recommends using more electrical tape as a potential solution.
  • Brian notes that adding more tape did not resolve the issue and mentions that the problem seems to occur specifically at the solder joint.
  • Brian also points out the wiring configuration, which transitions from solid to braided wire and back to solid, and mentions the presence of a resistor on one wire.
  • After cutting the wiring to the directional buttons, Brian observes that the issue persists, leading him to suspect a problem with the controller itself.
  • A later reply advises against using electrical tape and suggests alternatives like heat-shrink tubing or liquid latex for better insulation, while also considering the possibility of a short due to physical proximity.
  • The same participant expresses doubt that body capacitance alone could cause the malfunction and recommends checking for cracks in the circuit board.

Areas of Agreement / Disagreement

Participants express differing opinions on the best methods for shielding the solder joints and the potential causes of the issue. There is no consensus on a definitive solution or the exact nature of the problem.

Contextual Notes

Limitations include the lack of detailed information about the circuit design and the specific components used, as well as unresolved questions regarding the role of body capacitance and the integrity of the circuit board.

Briant22
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Hello, so I recently modified a gamepad to make my own arcade controller. However I have run into an issue which I do not quite understand. Sometimes the left button will trigger for no apparent reason when the down button is being pressed.

First of all, each of my wires to each button have a solder joint which is covered with electrical tape. So I examined it and I found that if my hand was near, or touching the solder joint (covered in electrical tape) of the left button while I was holding down, the left button would fire.

What's going on here? And how can I shield it so that it stops?

Thanks
-Brian.
 
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Briant22 said:
[1]What's going on here? [2]And how can I shield it so that it stops?

1) High impedance input maybe.
2) More tape
 
Thanks for the reply, I read up a bit on high impedance and it sounds like that might be the case.

I tried adding more tape like you suggested though, and I still receive the same problem. It is really odd, it only happens where there is solder joining the two wires. If I touch the electrical tape it will trigger, but if I touch the insulation on any of the wires it won't.

I should probably also mention that the connection goes from a solid wire to a braided wire to a solid wire again (I don't think that should change anything but I figured it would be worth mentioning). Additionally I have a resistor on one wire.

EDIT:
So I decided to cut all the wiring going to the directional buttons, however the problem continues to persist. I can press down on the tangled wires of the other buttons and it will cause the same problem to occur. I have a feeling it is my the controllers problem, so I might just have to replace it.
 
Last edited:
Hi, Briant.
I tried to respond to this question first thing this morning, but as you can read in GD, my internet connection has been giving me fits for a few days. I started trying to get on line at 8:30 this morning, and just managed to do so an hour ago (8:00 pm).
Anyhow, electrical tape should never be used unless there's no other option. Heat-shrink tubing is far superior, or you can paint the joints with liquid latex, silicone sealant, or potting compound. My best guess is that the physical proximity of your finger to the joint is causing a temporary short to the second pad. I doubt very much that your body capacitance would be sufficient to cause such a malfunction. Also, make sure that there are no cracks in the circuit board, since those can also lead to shorts.
 
Thanks for the tip, ill be sure to keep this in mind when I rewire it.
 

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