intercom switch


Old 11-19-12, 02:30 PM
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Join Date: Nov 2012
Location: USA
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Question intercom switch

I'm trying to fix a few of the intercoms in our building. Right now sourcing the correct momentary rocker switch has been difficult. For some reason 8 pin switches are hard to find. Anyhow, I've located a source but am looking for a way to test the switch to find out if it's a on-on-on switch or on-off-on. Any insight would be greatly appreciated.

Wiring wise I'm thoroughly confused as to why some wires connect across switches rather than on the same switch but different terminals. Are they doing that just to find a different ground, or does it provide a different function?

The pin diagram I've attached I pulled from another website. Which side works as the positive and which is the ground?

For reference I've attached images of the intercom. It's a Rittenhouse Emerson M7915, if that helps.

Thank you to anyone who might chime in.
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Old 11-19-12, 07:15 PM
CasualJoe's Avatar
Join Date: Jan 2010
Location: USA
Posts: 9,383
I can't help you and probably no one at Emerson would be able to help either since that product is wayyyyy obsolete. Try these folks.

Rittenhouse :: Repair Services for Industrial and Commercial Customers
Old 11-21-12, 05:36 AM
Join Date: Apr 2007
Location: Near Buffalo, NY
Posts: 4,239
There is no positive or ground on the switches. They are passive devices that perform a function depending on how they are wired.

Looking at the photo & pinouts, the switch is a three position double-pole. If it springs to the center position when released, it's a momentary.

In the left position, pin 1 is connected to pin 2 and pin 5 is connected to pin 6. And so on. Pins 1 and 2 are not connected to 5 and 6. You can verify this with a multimeter set to ohms.
Old 11-21-12, 09:26 PM
PJmax's Avatar
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Join Date: Oct 2012
Location: Northern NJ - USA
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I'm guessing the swithes are noisy or not always making contact versus being physically broken.

A good cleaner can take care of that. I use Blue Stuff and De-Ox-Id.

Blue stuff comes out blue and has microfine particles in it to burnish switch contacts. This stuff is incredible and very hard to find.

De-ox-id is widely available and although it doesn't have the fine particles in it - it works excellent also.

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