How Does a Touch Pad Work?
A touch pad in an appliance connects to the electronic control board and signals a selection or setting for a cycle or function in the appliance. Two types of touch pads are used in appliance – resistance (or membrane) touch pads and capacitance touch pads. In this article, we’ll discuss how each type of touch pad works.
KEY TAKEAWAYS
- A membrane touch pad embeds mechanical switches under the marked plastic cover and you activate the switches by pressing on the marked spots on the keypad cover to make selections.
- A capacitance touch pad has a smooth or hard surface and detects key presses when your finger touches the marked area to activate a selection.
- Learn about how to fix common touch pad problems and how to keep the keypad working properly in this article.
How Does a Resistance Touch Pad Work?
A resistance or membrane touch pad has buttons covered by a film of plastic. Wires connect the touchpad to the electronic control board of the appliance. When you press a button on the touch pad, the electronic control board senses the button switch being activated and takes action or adjusts settings according to the selection.
You’ll find membrane touch pads commonly used on all types of appliances including dishwashers, ranges, refrigerators, washers and dryers.
How Does a Capacitance Touch Pad Work?
Capacitance touch pads are more complicated in design and function that membrane touch pads. You’ll often find capacitance touch pads on ranges, oven and refrigerators. The touch pads will have a hard surface with selection buttons marked on the surface.
Capacitive touch pads detect finger touch contact by creating an electrostatic field along the hard conductive surface. When your finger that conducts electricity touches the hard surface, it reduces the system’s capacitance at that point. The system then determines which button was pressed and translates this to input data and transmits that data to the appliance electronic control board through a wiring harness.
What Can Go Wrong?
A number of different problems can prevent a touch pad on your appliance from working.
Common Membrane Touch Pad Problems
Switches inside membrane touchpads can sometimes break or get stuck.
Stuck Button on the Keypad
When a switch gets stuck in the engaged position, it will provide constant input to the electronic control board. Most of the time, the electronic control board will stop operating and display an error code or cause lights to blink indicating the control detects a stuck button.
You can sometimes free up a stuck button by firmly pressing all buttons on the touch pad. If you can free up the stuck button, the appliance will likely work normally.
Sometimes, you’ll need to reset the electronic control board after freeing up a stuck button so the appliance will work normally. Follow these steps to reset or reboot the electronic control board in an appliance:
- Unplug the appliance or completely disconnect electrical power to the appliance by shutting off the house circuit breaker for that appliance.
- Leave power off for 5 minutes.
- Restore power by plugging the power cord back in or resetting the house circuit breaker for the appliance.
If you’re unable to free up a stuck button and restore normal operation to the appliance by following these tips, you’ll likely need to replace the touch pad. Schedule appliance repair service to have a Sears Home Services technician visit your home and replace the touch pad.
Shorted or Open Button on the Touch Pad
Even though a button isn’t physically depressed, the button could be shorted or electrically stuck in the selected position. A button can also be broken in a way that it won’t close the electrical connection inside the switch when you press the button in.
In this situation, the touch pad will almost always need to be replaced. Individual buttons on an appliance touch pad typically aren’t available as replacement parts.
Wiring Failures
Many membrane touch pads connect to the electronic control board through a ribbon cable. A folded, kinked or damaged ribbon cable can interrupt signals between the touch pad and the electronic control board. When the touch pad fails and you find a damaged ribbon cable, you’ll typically need to replace the touch pad because the ribbon cable often isn’t available as a separate part. If the ribbon cable is available as a separate part, then replacing just the ribbon cable will often fix the problem.
Some membrane touch pads connect to the electronic control board using a wiring harness with a set of separate wires. With this type of connection, you may be able repair damaged wires instead of replacing the entire wire harness or replacing the entire touch pad assembly if the wire harness isn’t available separately.
Common Capacitance Touch Pad Problems
Common capacitance touch pad problems include:
- Unresponsive touches.
- Ghost touches.
- Inaccurate touch detection.
- Dirty screen.
- Damaged touch pad.
Issues with extreme temperatures or excessive moisture can also cause problems.
If you have a brand new appliance, failing to remove the protective film from the screen will affect performance or prevent the touch pad from working.
Fixing Capacitance Touch Pad Problems
Many capacitance touch pad problems can be fixed by cleaning the screen using a soft cloth. Fingerprints, dirt or grease can accumulate on the screen and interfere with the touch pad detecting touches properly.
Unplugging the appliance for 5 minutes then restoring power can sometimes fix problems by rebooting the electronic control board so the touch pad operates properly.
When these tips don’t work, you may need to recalibrate the capacitance touch pad. Follow the instructions in the owner’s manual for your appliance to recalibrate the screen. This typically involves:
- Go to the device settings menu.
- Select the Calibration setting.
- Follow the on-screen instructions for touching specific points on the screen in order to adjust the touch sensitivity and accuracy of the display.
- Exit the settings menu.
Check Wiring Connections
Loose or damaged wiring connections can prevent a capacitance touch screen from working. Unplug the refrigerator and check the wire harness connections between the touch pad and the electronic control board if possible. If not, schedule appliance repair service and we’ll send a Sears Home Services technician to your home to fix the problem.
Schedule Annual Maintenance to Keep Your Appliances in Top Shape and the Touch Pad Working Properly
Annual preventive maintenance by a professional technician will help keep your appliances in top shape. During maintenance, the technician will check the operation of the touch pad and make any adjustments necessary so it operates correctly.
Having your appliances professionally cleaned and maintained yearly will also help them last longer. Schedule appliance maintenance service now.
Schedule your kitchen appliance repair now!
From refrigerators to dishwashers, our experienced technicians are equipped to repair all your kitchen appliances, providing fast and reliable service.
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