Cell Phone Micro Switch

D. Vautier
posted 12/14


A lot of the new cell phones develop defective micro switches.  There are usually three micro switches on a cell phone, on/off, volume-up and volume-down.  The second pair of switches usually are good for the life of the cell phone but the on/off can fail.  Numerous sites demonstrate how to replace the on/off switch but it's good to know how they work since they are so small and it's hard to see what to solder.

The on/off is very small and comes with two pigtails.  It is an instantaneous type switch which means that the circuit is closed as long as it is depressed. The pigtails on each side lock the switch in place and provide the ground.  There is a third ground to the back center that is soldered flush with the board.  The two hot leads are to either side of the back solder point. These two hot points should be normally open and closed when the switch is depressed (or clicked).

It is difficult to test the on/off switch but you can do it by connecting small wires to the two points of contact in the back of the switch but you need to avoid the ground.  Switches can get loose and not work or stay closed.  Sometimes the surrounding ground can be tightened with a pear of pliers.




Here is a picture of a new switch as viewed from the bottom.  Notice the two pigtails and the back point where it is to be soldered.  the two hot points are to left and right of the back.





Just for fun I took a switch apart.  it consists of a concave metal plate that strikes against another plate that gives you the click. 

Here is another view of a new switch on it's back.







Here is the circuit board after switch removal.  there are two holes in the front. and three points of contact on the back which are flush with the board.  Knowing this will help you solder.