Sennheiser EM 100 G2 Service Manual download pdf (Page 8)

EM 100 G2, EM 300 G2, EM 500 G2

08/2004 8/32

3.1.3 Evaluation of the TX battery signal

The battery telegram sent by the transmitter reaches the U60-2 trigger stage, at

whose output appropriate square wave signals are available for evaluation by U1,

via the 4Hz low pass filter with U60-1.

3.1.4 Evaluation of the pilot signal

The 32.768kHz pilot signal sent by the transmitter is filtered from the signal mix

by the active crystal filter with Q95, Y95 and U95-1, rectified via the D95 diode and

made available for evaluation by U1 via trigger stage U96-1.

3.1.5 Functions of microprocessor U1

The receiver is controlled by the 8-bit U1 microprocessor, which contains in its flash

memory the control program and uses a sub-area as an EEPROM for saving data

even in the event of power failure. The microprocessor uses a 4MHz crystal to

generate both its own internal 8MHz cycle and the reference frequency for the

RF module PLL. It processes the signals already described in line with the program

specifications and the user specifications that can be set on an individual basis via

a menu.

3.1.6 Service interface (RJ45 socket)

The service interface “DATA“ with RS485 protocol, located on the back panel of the

unit, fulfills an important function. The RJ45 socket allows the relevant EEPROM pa-

rameters on the RF module and the simulated EEPROM to be read out and modified

in the microprocessor. This interface also enables a software update as part of the

hardware options. For example, the RJ45 socket enables you to read unit data and

write-in after replacing a board. The necessary service software is

available for download free of charge on our Internet homepage:

www.sennheiser.com > Service & Distributors > Service Documentation >

Download

3.2 RF module

The RF module is a single-sided PCB assembly that is fixed to the back panel via the

BNC input sockets and to the mainboard via a sheet metal brace. The RF module

performs RF conditioning until demodulation of the IF signal. The module is connec-

ted to the mainboard via a 15-pin ribbon connection; the following functions are

performed by the plug-in connection:

• Incoming power supply of 5V DC from the mainboard.

• Incoming system cycle (4MHz) from mainboard microprocessor.

• 2 x outgoing AF voltage to mainboard

• 2 x RSSI voltage to mainboard.

• Communication between the mainboard microprocessor and

the EEPROM or the PLL for the RF module.

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Sennheiser EM 100 G2 Service Manual Page 8