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Our home has a Paradox brand security system with a keypad:

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Over the years the keypad had become more and more unreliable to the point where the 0 key was very difficult to press successfully, and the 4-digit access code used a 0. A service person who was replacing the battery added an access code which was the old one but with the 0 changed to a 1.

A year or so on, and the same problem has developed with another key, so I looked into adding an access code myself. Turns out, the procedure for changing/adding access codes requires a master access code to be entered. The default access code according to the manual is 123456 or 000000, but the first one doesn't work, and the second one involves pressing the 0 key, one of which I don't have. I believe these keypads usually work by pressing a conductive polymer against contacts on a printed circuit board. I would like to try cleaning this contact interface. Does anyone have any experience with this? In particular:

  • is there a magic trick to getting the front fascia off?
  • is the keypad likely to have an anti-tamper switch which will trigger the alarm, even is it isn't armed?
  • can anyone offer advice as to what it is best to use to clean the contacts, assuming I can access them?
  • Feasible : depends on your skills. Worthwhile - depends if it is to make a profit or you just want a project. – Solar Mike Apr 30 at 6:32
  • Hi Mike. What I'm after I suppose is comments of the form: "I've done this - it's really easy", or "Don't even think about it". ;-). Taking the thing apart holds no fears (I'm an EE), but I don't particularly want to set off an alarm that I can't silence. – rossmcm Apr 30 at 6:41
  • There are several different technology's in key pads older school do have contacts , some use inductance , a quality contact cleaner may be able to clean things up just make sure it is plastic safe. As far as an alarm if the unit is turned off I don't see how it could alarm. Since you are having problems with it I would try to clean it. If cleaning works you may get a few years, if not it was worth a try. – Ed Beal Apr 30 at 13:46
  • Thanks @Ed. I met an alarm in the past where disarming the alarm did not disarm the anti-tamper contact and the thing went off as soon as I popped the front panel from the box, hence my nervousness. I can't remember what happened but I presume it stopped when the Lead-Acid battery in the cabinet was disconnected. – rossmcm May 2 at 6:04
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These types of keypads have a rubber membrane with the buttons on one side and conductive material on the other placed above a circuit board with contacts. Crud or oxidation can build up on the back side of the buttons or on the circuit board and cleaning it can often help and get you some more years of use out of it.

Generally they are easy to disassemble and you can clean the back side of the buttons gently with a damp cloth and the circuit board with some compressed air or some circuit board cleaner.

As far as taking it off, you will probably need to take it off the wall first, then find the screws that hold it together or the latches that hold the case halves together.

  • No visible screws. I think the front fascia must unclip. – rossmcm May 1 at 0:44
  • Most likely. A handy tool to have is a "spudger" that comes in one of those cell phone repair kits. They really help taking these things apart without damage. – jwh20 May 1 at 1:28

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