Motorola RADIUS GM300 Manual de serviço - Página 39

Procurar online ou descarregar pdf Manual de serviço para Rádio Motorola RADIUS GM300. Motorola RADIUS GM300 49 páginas. 16-channel, conventional fm radio
Também para Motorola RADIUS GM300: Manual de serviço (28 páginas), Manual de Instruções (18 páginas), Manual de Instruções (19 páginas), Manual do utilizador (37 páginas), Instruções de utilização (2 páginas)

Theory of Operation

Front Panel Boards

Vol/Mic Board

The VOL/MIC circuit board provides mounting and

electrical connection to the microphone jack J11 and the

on-off/volume control R9002. Connections are made to

the logic board via P8. This cable/connector assembly

also contains the two wires which route receiver audio

to the internal 22 ohm speaker mounted in the front

panel.

A 10 ohm resistor, R9001, is located between the CCW

side of the volume control element and ground. At

minimum volume setting, this maintains the attenua-

tion at no greater than 46 dB, to avoid missing a mes-

sage if the volume control is inadvertently turned to

minimum.

2-14

The front panel Þlter board is mounted to the front of

the radio chassis. The pins of logic board connectors J8

and J9 pass through this board and are soldered to it.

This board allows capacitive bypassing of all signal

leads leaving the front of the radio chassis. This, com-

bined with the shielding covers over the RF board,

logic board and RF power ampliÞer, reduces the levels

of cabinet radiation to extremely low levels.

In addition, the front panel Þlter board also provides

protection against electrostatic discharge into front

panel controls or indicators. Zener diodes are installed

on any lines which are susceptible to damage from

excessive static voltage transients, limiting voltage

excursions to +27V or -0.7V DC.

68 No.

Name of Manual

March, 1997