My doorbell has stopped working. I am trying to test each of the components using a multi-meter.

However, the wires seem to go through the ceiling etc, so I can't trace where they are going or what they are for.

I have identified a box which I think may be the transformer though:

possible transformer

Using the multi-meter, I measured voltage AC by connecting the red lead to the screw and the black lead to ground. I got:

  • (2) having 250V AC
  • (3) having 18V AC
  • (4) having 10V AC

  • Between (1) and (2), I got a reaching of 250V AC

  • Between (3) and (4), I got a reading of 12.5V AC.

Is this enough to establish that (a) this is the transformer, and (b) it is working?


Yes, your method is sound.

Another method is to momentarily touch the line 3 and 4 together, and if good will have a tiny arc. This can be done easily at the door bell button. Once you remove the button off the wall undo one of the lines and momentarily touch it to the other line.

Usually the button will go bad or the chime. By bypassing the button as described above, you're one step closer.

  • Hi. Thanks for your answer. What do you mean "have a tiny arch"? – Tahir Hassan Sep 18 '18 at 11:18
  • 1
    Basically by momentarily touching the 12v lines together will create a tiny arc. (Spelling) – Kris Sep 18 '18 at 11:57
  • Oh, I see, like a spark, I understand now. – Tahir Hassan Sep 18 '18 at 14:22
  • Hi, I use a foil and joined the two 12v lines together. There was a spark (arc). However, when I touch the two button wires, nothing happens. – Tahir Hassan Sep 18 '18 at 14:32
  • Sounds like a bad chime – Kris Sep 18 '18 at 15:46

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