Digital Board - Tait TM8100 mobiles Service Manual

Input Signals
( 1 to
3)
AUX GPI AUX GPI
ESD Protection
Hookswitch
Detection
3.8

Digital Board

Introduction
TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
Dedicated inputs are provided on three pins of the auxiliary connector
1 to 3).
(
AUX GPI AUX GPI
protection of the same type used for
dedicated emergency input but can be made a general-purpose input like
1 by removing the link LK3 in the power supply area.
AUX GPI
normally a dedicated ignition-sense input but can be made a general-
purpose input like
AUX GPI
area and fitting the 33kΩ resistor R775.
On exposed inputs of the auxiliary and control-head connectors ESD
(electrostatic discharge) protection is provided by a 470pF capacitor and by
clamping diodes to ground and to 13.8V. For example, on
consists of D713 and C725. The lines
connection to internal digital devices and so these have relatively light
protection.
Hookswitch detection is performed by Q700, R709, R706 and R712.
When the resistance to ground on the PTT line is less than 13.2kΩ, Q700
will turn on and drive the
microphone is on hook or that the PTT (press-to-talk) switch is pressed.
Different digital boards are used for the TM8200 and TM8100 radios.
For a block diagram of the digital board of the TM8200 radios, refer to
Figure 3.13. For a block diagram of the digital board of the TM8100 radios,
refer to Figure 3.14.
The digital board is not serviceable at level-2 and is not described in this
manual.
1 is a general-purpose input with strong
AUX GPI
AUX GPIO
1 by removing the link LK2 in the power supply
IOP GPIO
line high; this indicates either that the
ITF CH HOOK
4. 2 is normally a
AUX GPI
AUX GPI
AUX GPIO
1 to 7 are intended for
IOP GPIO
Circuit Descriptions
3 is
4 this
93