House Intercom

A Rittenhouse Intercom was installed some time in the 1970s(?) and extended to the Pool Room in the 1980s. The master station is in the Kitchen next to the Pantry, and each main room (except the Study and the Lounge Room) and the two bathrooms have a remote station. It is likely the Study used to have a station since there is an unused set of wiring at the master station.

It is a Rittenhouse Model M9040 / Emerson M9047 with nine M9302 interior remotes (brown) and two M9312 exterior remotes (white). As well as the colour, the exterior remotes are different in having a plastic film in the speaker grill.

I was able to obtain a downloadable basic service manual from SAMS Technical Publishing. SAMS #1920-3 covers Rittenhouse intercom models M9040..M9047 and is a SAMS Photofacts PDF reproduction of the circuit diagram for the master station and remotes, a parts list, and several board and component layouts. It is not complete however, since on the model I have the push-button switch board in the master station has undocumented several components around an LM380N amplifier IC that is presumably used to drive the speakers in the remote stations.

A copy of SAMS #1920-3 is available here (2.2 MB) for reference. Remove the extension ".sav" to view as a PDF - the extension is to defeat the PDF leachers that appear to be common.

The intercom has Monitor, AM, FM radio and Aux functions. I installed a coax socket on the front wired to the Aux input so an iPod or similar can be plugged in.

The entrance and back door speakers are wired to the master station using grey twin flex, as is the Rittenhouse door chime. The chime for the front door is a 'ding-dong', whilst that for the back door is a 'dong'. If the chime is activated, it is sounded through the intercom which mutes the radio if necessary.

Several of the remotes required considerable effort to get them working after many years of neglect. The most common problem was that one or more of the push button switches were not making contact. This required disassembling each switch and cleaning and lubricating it with silicone spray. On some the volume control was broken and had to be repaired. The control is a 160 Ohm 2 W wirewound potentiometer of good quality, but the harsh conditions in the Pool room and outside on the Patio had taken their toll on the connectors. On these too the circuit board was corroded but no tracks were broken so a scrape and spray with WD40 was all that was needed.

The picture is actually for the master station, but is the same for the remotes.

The master station was also serviced and the 11 cables for the remotes were tidied up, labelled and rewired to the terminal boards as per the schematic shown here. The cables are 4 x twin solid twisted pairs in a black sheathing, similar to but not the same as Cat 5 cable.

The eight selector switches on the master station have been wired as follows:

where counting from the master bedroom as Bed 1, children's bedroom as Bed 2, guests bedroom as Bed 3, and the small bedroom as Bed 4.

LINKS

• SAMS Publishing https://www.samswebsite.com

Intercom

Rittenhouse Intercom with Aux Input and new labellling for Remote Selector.

Inside the master station. Remote cables are labelled. Unused live mains wiring in the wall.

The tuner board is centre bottom, amplifier board at the top. The function switch board is upright on the right.

The master station relay board is in the centre. Original remote wiring on the right.

Rewired terminal boards. Cables for the remote stations are now labelled.

Rittenhouse Intercom Remote Station.

Inside a Remote Station.

Servicing the selector switches in a Remote Station. The potentiometer has new leads.