I have a 4-wire (I think) intercom/doorbell system in the my house with 3 indoor stations (Pacific Electronic 3404) and one outdoor station.

Wiring diragram My transformer is in the (finished) basement on the west wall of the house; the intercom stations are roughly in the center of the house, and the door is on the southeast side of the house. All wires immediately go behind sheetrock.

I haven't been able to find the AF-1000 master unit anywhere in the house, though i know that it is somewhere in there.. Is there a procedure that I can use to find it short of ripping out all the sheetrock to trace the wires?

I can't imagine that it is up to code to put this behind sheetrock, but I've looked all over the house for it.

picture of af-1000

  • 1
    Can you post some pictures? In my experience, I have always seen master units being significantly more complex (having more buttons) than other units. – DarthCaniac Sep 17 '15 at 13:29
  • Have you opened up any of the units, because I have see them put the master behind some of the bigger units. If you open and find it, label that unit so you do not forget it. – WarLoki Sep 17 '15 at 16:45
  • I've removed the three interior units from the walls and looked behind them. Might try taking the metal box outside the house apart again and looking in there; seems like a security hazard to put the door striker control in a metal box outside such that an intruder could simply open the box and jump the solenoid with a battery. – gbronner Sep 17 '15 at 16:48
  • Looked behind the outside unit; it had 3 doorbells along with a speaker. No trace of the master unit there. – gbronner Sep 21 '15 at 14:29
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    It should be someplace very near to its transformer. Use a wire tracer from there, following the low-voltage wires from the transformer. – TDHofstetter Sep 22 '15 at 22:55

You should be able to use an inexpensive wire tracer to follow where the wires from any of the stations are going. Even the cheap wire tracers will work through sheetrock.

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  • Interesting-- didn't realize that these worked through sheetrock, as I've only seen the contact type used by the phone company. Also impressed that the CEO of Fog Creek does his own electric work... – gbronner Sep 23 '15 at 21:49
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    I have a unit like the one pictured and the "pen" part has a sensitivity wheel on it. When turned all the way down its basically a contact tester. Turned all the way up, the range can be impressive in some situations. – JPhi1618 Sep 24 '15 at 15:59
  • Joel Spolsky's answer was correct. I eventually bought one of these, and, after running all over the house, eventually found the master unit buried in a wall cavity behind the outside unit. Terrible installation, terrible location, and the receiver is strongly affected by distance to the sheetrock. A tip: Avoid attaching the transmitter to the low voltage AC wires -- it will cross the transformer and cause all of the electric wiring in your house to signal the receiver. – gbronner Sep 28 '18 at 4:36

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