IS401B ( IS401B ) Mircom Intercom Station

Troubleshooting Mircom Apartment Intercom System
Mircom MA-485 Amplifier

Entire System Dead
Check for 16 VAC at transformer secondary and 120 VAC at transformer primary. Review field wire and perform direct test using one of the apartment stations to eliminate field wiring.

No Talk
Check wiring to terminals 1 and 3, and check whether wiring to entrance jury speaker is shorted or open. suite post can be swap tested with another working unit of measurement.

No Listen
Check wiring to terminals 1 and 2, or for short between terminals 1 and 2. Check to see if wire to entrance jury loudspeaker is shorted or candid. suite station can be swap tested with another working unit.

No Door Operation
Check wiring to door unblock for shorts and opens, or for bad door unblock. Confirm that shunts are by rights set for door release type and that connections to appropriate output have been made. Check wiring to terminals 2 and 3, or 1 and P ( depending upon cortege post type ).

No Call Tone
Check wiring to terminal Z to entrance panel, refer entrance panel call buttons, and suite station X terminal. suite place can be swap tested with another working unit.

Excessive Hum or Distortion Check whether wire is installed besides close to electric wiring or electric devices ; amplifier installed besides near to transformers or other electrical devices ; twisted couple wiring not used as required ; or amplifier part volume set excessively high.

Radio Interference
Connect G terminal from amplifier to electrical ground. note : This connection is not shown on the electrify diagram, since the site is not always improved by adding it. If the trouble persists, consult the factory or service example.

Oscillation (feedback or howling)
Reduce the voice volume until oscillation is eliminated. If oscillation stops when the call tone wire is removed from ZW, set entrance tonicity ( SW3 ) to the OFF ( left ) position.

Signal Flow and Theory of Operation for MA-485 Amplifier and Apartment Intercom System
The come exemplar describes an apartment intercommunication system system using a MA-485 in concurrence with a 4-wire post.

Call Button
Pressing a suite station call release on the entrance panel routes the call tone from the Z end on the MA-485 to the X end ( tone in ) on the associated cortege place. This signal then passes through the loudspeaker and returns to the MA-485 via the 1 concluding ( sound recording common ).

Talk Button
Pressing the talk button at a suite place connects the suite station ’ s internal loudspeaker to terminals 1 and 3 of the MA-485, which serves as an sound recording remark to the amplifier. The audio is then amplified and sent to terminals S1 and S2, which are connected to the entrance panel ’ south speaker ( speaker modality ).

Listen Button
Pressing the listen button at a cortege place connects the suite station ’ s internal loudspeaker to terminals 1 and 2 of the MA-485, which serves as an audio output from the amplifier. This allows the suite post to receive the magnify audio being received by the amplifier on terminals S1 and S2 from the entrance panel loudspeaker ( microphone mode ).

Door Button
Pressing the door button at a cortege station creates closure between terminals 2 and 3 on the MA-485. This department of state is sensed by the amplifier and causes the door let go of to be activated. This express is besides triggered by shorting terminals 1 and P as is typically done by a postal lock.

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