CS-TRH3 Service Manual Page 8
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Lincast International Pty. Ltd. Ref: 04 Doc-04 19/7/13
TECHNICAL DESCRIPTION
Interconnect
All components are mounted on one Motherboard which runs the length of the case. The LED provides
indication that external power is present.
Power
Internal power is provided by a 700mA / 10.8V battery situated in the base of the controller. When any
button is pressed, (eg -S3) the base of Q9 is grounded via D5, R10. Q9, Q5 both turn on, supplying
power to the IC regulators IC9, IC10. IC10 provides 5V to the PCB and IC1 is reset by the pulse applied
to IC1-9 by C3. S3 also grounds IC1-13 (INT 1) via D1 which initiates the program. IC3-6 goes high,
turning Q6 on via R9. Q6 collector holds the base of Q9 low via R25, thus holding power on.
After 5 minutes of no button activity, IC3-6 goes low and turns Q6 OFF. Q9 turns OFF which removes
power to the IC regulators.
External power is applied directly to the IC regulators via protection diode D2. The battery is trickle-
charged via D4, R34 while external power is applied.
IC9 is an adjustable regulator which supplies the transceiver only and is adjusted so that the transmitter
gives out .9 of a watt.
Voltage Sensing
The voltage which is applied to the input of the regulators is also applied to the voltage sensing circuit via
R5. The voltage divider R6, RV1, R7 provides a voltage at IC6-3 which is compared with an internal
reference. If the voltage on IC6-3 goes below that reference, IC6-4 goes low and a LOW BATTERY
indication is given.
Micro processor
IC1 is a micro processor complete with 256 of RAM and 16K of ROM. Also it has its own internal
oscillator and UART. Port 1 is a multiplexed Address/Data bus but is used only to send and receive data
from IC3 & IC4. IC2 is an address decoder which selects IC3 or IC4.
IC8 is an EEPROM which stores the system address. It is selected by IC3-9 and clocked by IC3-12. Data
to and from IC8 is provided by IC1-1 & IC1-2.
Control
IC4 is a tri-state buffer which is enabled when a button operation has been sensed by IC1.
D9 to D12 are to prevent the 10.8 volts from the battery being applied to the IC4 inputs via Q5, Q9, R10
& D5 to D8. Assume the STOP button (S4) is pressed. IC1-13 is held LOW via D6, D1 which initiates
the selecting of IC4. IC4-4 is held low via D11 which is applied to the data bus, read by IC1 and the
appropriate action occurs.