Liquid Crystal Display (Lcd); Microphone Connector; Electrostatic Transient Protection - Motorola GM-950 Manual

3.6

Liquid Crystal Display (LCD)

The LCD display H0931 is a 3 digit / 7 segment display which incorporates (11) annunciators. Data
is loaded serially into the display driver U0932 via the SPI interface. The display data of line SPI
DATA BUF is shifted serially into the display driver by clock signal LCD CLCK BUF. When the last bit
has been received, the LCD display is updated.
3.7

Microphone Connector

Signals BUS+, PTT, HOOK VPP, MIC HI, HANDSET AUDIO from the microphone connector (J0903)
are fed to the radio's controller section via connector (J0901) .
3.8 Speaker
The Control Head contains a speaker for the receiver audio. The receiver audio signal from the
differential audio output of the audio amplifier located on the radio's controller is fed via lines INT
SPKR+, INT SPKR-, connector (J0901-18,17) to the speaker connector (J0902) pin 1 and pin 2. The
speaker is connected to the connector (J0902) .
3.9

Electrostatic Transient Protection

Electrostatic transient protection is provided for the sensitive components in the Control Head by
diodes (VR0901 - VR0909). The diodes limit any transient voltages to tolerable levels. The
associated capacitors provide Radio Frequency Interference (RFI) protection.
3.10 Reversible Control Head
The control head is connected to the RF transceiver by means of a short flexible ribbon cable. This
allows the control head to be mounted either way up in relation to the body of the transceiver. This
means that the transceiver can be mounted in the most cosmetically pleasing and most efficient
cooling orientation and still have the user interface the "right way" up.
Introduction/Theory of Operation
Theory of Operation
4B.1-3