How to Repair a TV Remote Control or Alarm Keypad With Kitchen Foil
How Do I Fix a Remote Control or Keypad That Won't Work?
Rubber membrane keypads are widely used on burglar alarm panels and remote controls for TV, audio, satellite boxes etc. Keyboards on laptops are now often rubber membrane types, with dome switches mounted on top for tactile feedback. If you look inside one of these keypads, there are lots of little rubber pads on the underside of the buttons which push against a circuit board when you press a key. The surface of these rubber pads is impregnated with carbon to make them conductive, so that when the pad makes contact with pairs of metal contacts on the PCB (Printed Circuit Board), it completes a circuit, triggering the circuitry to do something (e.g. send out an infrared signal to a TV, or register a digit on an alarm panel). Over time, the conductive coating can deteriorate and also the contacts on the PCB can become dirty.
If you can't source a new remote control or alarm keypad, or don't want to use a universal remote, you can try cleaning or repair the keypad.
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Getting Keys to Work on a Remote Control
There are several steps to getting a remote back working again:
- Open the remote, it may be held by screws, clips, or the two halves could be plastic welded or glued together
- Clean the control with washing up liquid or rubbing alcohol. This may temporarily restore functionality
- If cleaning doesn't work, you can repair the keypad with electrically conductive ink or graphite, replace the pads, or use aluminum foil
First Things First - Check the Batteries!
If your remote doesn't work, check first that the batteries aren't exhausted. You can use a battery checker, or simply try inserting fresh batteries. Also the electrical terminals in the battery compartment which make contact with the batteries can become tarnished and fail to conduct current. Try cleaning them with wire wool, fine sandpaper, a nail file or similar.
Is the Remote Control Sending Out an Infra Red Signal?
The key fob for your car transmits a radio signal to operate locks, however remote controls for TVs and other consumer electronics send out an infra-red signal when you press a button. The signal is emitted by an LED at the front of the control. You can't see this with the naked eye, however if you view the remote with a digital camera or phone, it is possible to detect this signal which appears as a flashing light. If this isn't apparent, check for any loose soldered connections when you open the control.
Opening a Remote Control or Alarm Keypad
First things first, remove the batteries!
Remote controls can be held together with screws, clips, by using a plastic welding/glue bonding technique, or a combination of these methods. Screws are often located in the battery compartment, but sometimes can be hidden under rubber pads which you can prize out with an awl or narrow bladed jeweler's screwdriver. Once you've done this, try and pull the two halves apart. If they don't come apart easily or if there are no screws apparent, slide a blunt dinner knife into the crack between the two halves of the control to undo the clips, starting at one end. Hold the tip end of the blade between your thumb and forefinger. This gives more control and lessens the danger of the knife slipping out and stabbing you in the other hand! It's very easy to break the clips, so take care and prize the halves apart bit by bit. You need to feel your way along the crack and with a bit of practice its possible to locate a clip by sliding and pushing in at the same time (the tip of the knife sinks into an indentation). Twist the blade to undo the clip. Work your way all around the perimeter, and separate the two halves.
Remote alarm keypads generally have a faceplate held on by screws, so you don't need to do any of the above steps.
Cleaning a Remote Control
If the control is really dirty and sticky, e.g. someone has spilled sugared tea, coffee or soda on it, it will need to be cleaned. After taking it apart, you can wash the two halves of the shell, membrane keypad and circuit board in warm soapy water. I reckon its safe to do this because usually there's only one chip on the board and a few passive components and unlike a cell phone, no complex, high density, surface mounted electronics, or other modules which water could lodge in. Rinse the board, shell and keypad after cleaning, and allow to air dry, or dry with a hair drier.
If the control is unresponsive but hasn't got dirty as described above, you can try cleaning the conductive rubber pads with isopropyl alcohol. This is also known as rubbing alcohol or IPA. You can buy it in bottles or aerosol cans. Its sold in electronic or hobby shops as a cleaning product for circuit boards. Spray a little onto a small piece of paper kitchen towel and clean each pad and the corresponding tracks on the PCB. As an alternative, you can use a cotton bud soaked in alcohol for cleaning.
Cleaning the pads with alcohol usually works for a time but sometimes a remote becomes unresponsive again. Possibly this has something to do with the conductive layer on the pads permanently breaking down. The only solution then is to use conductive ink or alu foil to repair the pads.
Repair Option 1 - Using Electrically Conductive Ink or Graphite Repair Kits
There are several products available for restoring keypads which either involve using electrically conductive silver ink/paint or graphite loaded compound to create a new layer on the rubber pads. You need to clean the pads thoroughly, apply a primer and/or super glue and then paint the pads using the supplied applicator.
Repair Option 2 - Use Replacement Pads
Another option is to buy a kit of replacement pads and glue. After cutting off the existing pad, you apply a small dab of glue to the membrane and stick on a new pad, pressing it down to make sure it is attached properly. You can buy these pads here: Attilasebo Shop
Repair Option 3 - Use Aluminum Foil
The third option which costs virtually nothing and works quite well is to use aluminum kitchen foil ("tin foil") You need to have nimble fingers to do this and it can be a little tricky, but not overly difficult.
Step 1 - Cut the Foil Into Small Squares
With a sharp scissors, cut the foil into squares roughly the size of the pads. You don't have to be overly fussy about this, just don't make the squares too large.
Tip: A reader has suggested using a paper punch to cut out circles of foil.
Step 2 - Apply a Blob of Glue to the Pad
Super glue works quite well, but you can also try using contact adhesives or any other type of craft glue. Don't squeeze glue directly from the tube onto a pad, because too much is likely to squirt out, instead apply some to a pinhead, match stick, jeweler's screwdriver or similar, and spread it evenly over the pad.
Step 3 - Attach the Foil Square to the Pad
Super glue bonds within seconds, so it's important to position the foil properly on the pad. You can use a tweezers, small snipe/needle nose pliers or suction pickup to pickup the foil.
Step 4 - Press Down Firmly on the Foil Squares
Press down on the square and firm the edges of the square around the pad.
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Questions & Answers
I have a pioneer remote control unit CU0FD002 for Pioneer Hi-Fi equipment. The equipment was purchased in the early 1990s. The sleep function recently stopped working. I believe it has to do with the rubber membrane you wrote about in this article. My problem is opening the remote's case. The knife trick you suggest doesn't work, and it may be that the remote's clamshell is glued together. Do you have a suggestion as to how to open such a remote?
The chances are that it is glued together or possibly welded at various points around the perimeter. Make sure you've removed all the screws (some could be hidden under labels). A credit card is also useful for prying into the gap between the halves and would do less damage to the plastic than a knife. If you can separate the halves even a bit, you might be able to see where the snap clips are and push in and upwards to release them. Another possibility is to heat the edges of the control with a hair drier. Most glues soften with heat, so it may help to free the halves. Other than that your only option is to cut the control using a junior hacksaw or maybe a toothed cutting disk and Dremel rotary tool.
© 2015 Eugene Brennan