Headphones Module

Headphones Module

headphones module
The headphones module (KHM) will be introduced in the E70 as of 09/2007. This enables TV reception in the rear.
The headphones module is only installed in conjunction with the following optional extras:
- Optional extra 6FF "DVD system in the rear"
and
- Optional extra 601 "TV function"
or
Optional extra 602 "On-board monitor with TV"

Brief description of components
The following component is described:
- KHM: headphones module

KHM: headphones module
The headphones module has the task of converting the TV sound for the rear seat entertainment system (RSE), which is sent as an optical signal on the MOST bus, into an analog signal.







System functions
The following system functions are described:
- Signal processing of the TV sound
- Voltage supply

Signal processing of the TV sound
The headphones module is equipment attached to the MOST bus. The MOST bus connects the control units for the information and communications systems of the vehicle.
The headphones module is the interface between the MOST bus and the control unit for the rear seat entertainment system (RSE control unit).
The video module for analog and digital television (video module hybrid DRIVE) receives the TV signals via the TV aerials.
Whereas the picture signals are sent from the video module via the CVBS or RGB line directly to the RSE control unit, the video module sends the TV sound as a message (optical signal) on the MOST bus.
The headphones module transforms the optical signal into an analog signal. The headphones module transfers the TV sound as an analog signal via the audio lines to the RSE control unit. The RSE control unit regulates the audio output of the TV sound for the rear seat entertainment system (RSE).







Power supply
The headphones module is supplied with voltage by the rear distribution box via terminal 30g.

Notes for Service department

General information
The Rear Seat Entertainment system (RSE) is to be switched on for the diagnosis.
The headphones module can be programmed via the MOST direct access point.
In the RSE control unit, the diagnosis request "Status_Diagnosis_Aux2" can be used to check the audio lines coming from the KHM (headphones module).
The following status is displayed:
- Short circuit terminal 30 Audio In
(Terminal 30 short circuit at at least one of the AUX2 audio inputs
- Measure: check wiring harness or headphones module)
- Short circuit terminal 31 Audio In
(Terminal 31 short circuit at at least one of the AUX2 audio inputs
- Measure: check wiring harness or headphones module)
- KHM defective or wire fault
(Headphones module defective or wire fault to the headphones module
- Measure: check wiring harness or headphones module)

No liability can be accepted for printing or other errors. Subject to changes of a technical nature