Document TTY-OUT protocol

[probonopd]

The Acoustimass module connector has a TTY-OUT pin. can we document it?

[probonopd]

The service manual says:

The remote control commands for the external sources are translated and passed
to the serial data output jack. With the CE-I accessory device this data can be converted to
Infrared (IR) for use with many conventional audio devices.

Serial Data Output: 2-3.5mm stereo jacks , Tip: Serial data output, Ring: + 12V dc turn on output.

When an external source is selected (AUX, VIDEO, or TAPE), the transport commands (FF, FR, etc.) are passed through the serial data jack via Q401 and its associated circuitry.

Service Bulletin 174798-B2 says:

If a customer doesn’t fully insert the Acoustimass® powered speaker system’s serial data
cable into the serial data jack on the rear of the CD5, R428 will short to ground. The resistor
can not dissipate the excess power and burns open. With R428 open the CD5 will not turn
on the powered Acoustimass speaker system. Replacing the resistor with a 330 Ohm
resistor will prevent the resistor from burning open, if the serial data plug is not fully inserted. Refer to the CD5 service manuals, 174798 (CD5 I), 177871 (CD5 V), and 193461
(CD5V II) for schematics, test procedures, and disassembly/assembly procedures.