Overview

This page represents notes on work to create an intercom system for the Broadcast Television Engineering Technology (BTV) program studio from Telex RTS intercom components donated to the program.

Transfer Report

Here is the transfer report I prepared when leaving the role of guru/lead in the intercom team.

• Microsoft Word
• OpenOffice.org 2.0
• PDF

Inventory

Here are lists of intercom equipment we have as raw materials from which to build our intercom system.

Component Inventory

This list includes everything except for a collection of headphones that are listed in a separate table after this one. This component inventory was performed on Wednesday, 30 August, 2006. Component testing was performed on 11 September, 2006 and on 25 and 27 September, 2006, and other later dates as indicated in notes.

Headset Inventory

Here's an inventory of headsets, including the generous donation of headsets we recently received. The status information is as of 18 September 2006 and 27 September 2006.

Test System

The test system we used to evaluate the various components available to build the proposed intercom system include:

Basic Wiring

All master stations (802) connect via 50-pin cables to a system interconnect (862). The system interconnect connects to the power supplies via 3-pin XLR or 4-pin cable (female-male). The power supplies connect directly to belt packs via 3-pin XLR, connect to the ISO electronics box (VIE-306) via a 3-pin XLR female to 25-pin D female. or connect to a SAP (source assign panel) via a 25-pin connector.

The pin out for the 3-pin XLR female to 25-pin D female is:

• XLR 1 - shield - DB-25 pins 1-12
• XLR 2 - red - DB-25 pins 14-19
• XLR 3 - black - DB-25 pins 20-25

The ISO electronics box connects to its control panel (VCP-12A) via a 50-pin cable.

Pinout for the 4-pin cable

• 1 - Black
• 2 - Red
• 3 - Green
• 4 - White

Power the master stations with the AmData 5102 power supplies. There are three screw clamp connectors near the right of the master stations when looking at the master stations from the back. The two on the left are marked with voltages and the one on the right is marked as ground. Hook up the wire going from the positive output of the power supply to the leftmost screw clamp connector of that set of three. Hook up the wire going from the negative output of the power supply to the middle screw clamp connector of that set of three. We found it odd that we wouldn't hook one wire to ground instead of hooking both wires to what appear to be connectors expecting positive voltages, but that's what worked.

To Do List

• Figure out how to get channel 3 working on the ISO and other user stations. This is fourth priority.
• Retest all belt packs, 862s, 802s, power supplies, headsets now that we have two channels working (first priority - done)
• Design system enough so that Steve can build the SAP equivalent (third priority - done).
• Integrate Sony CCU-360 to prove we can simulate camera intercom in the TW system. The intercom is two-way with the CCU. Found that we can hear intercom OK at the test camera, but can't talk back. (second priority - done).
• Figure out how to wire up intercom channel output to audio patch panel so we can patch intercom channel(s) into audio board channel.

Master Stations

October 11, 2006 - Brian Mills found out that there are a set of DIP switches inside the Model 810 (no-speaker type) master station that enables/disables channels. We found this out by noticing one of the 810s would only talk out on channel 5, and then finding that we could modify this by modifying the settings of the DIP switches.

System Interconnects

October 11, 2006

We found out that we could connect system interconnects to each other via the 50-pin jacks. We used a male/female cable plus a male/male cable to connect two system interconnects together (the one in the server room and a newly installed one in the rack in the cabinet that holds the sliders for the light groups in the studio). Despite a vague recollection regarding not allowing breaks in 50-pin cables, the system worked fine because we were able to hook up a new 810 this way at Steve's desk.

We didn't need to turn on the system interconnect in the studio in order to couple the 810 at Steve's desk into the rest of the intercom system; the four 50-pin jacks on the back of the interconnect must connect to each other cold, so the system interconnect in the server room being powered was sufficient. I suspect that were we to connect a power supply up to the interconnect via a 4-pin XLR, that we would need to power on the interconnect.

Interfacing Intercom to Audio Board

On October 12, 2006, I looked through the manual for the Yamaha PM-3000C audio mixing console in order to find out how we could run intercom audio into a channel in the audio board, and also to figure out how to use the audio board as a user station. Pages 7-10 and 7-11 provide this information. These pages have diagrams of circuits you can build to send intercom audio to the console comm input, and to send audio from the console talkback into the intercom system. The same circuit used to supply intercom audio to the console comm input can be used to supply intercom audio to a jack on the patch panel; such a jack could then be patched into a channel on the audio console, allowing somebody to include intercom audio into a production.

Useful Links

RTS Intercoms