Nokia 232, 239 Service Manual hfj2
After Sales Technical Documentation
HF JUNCTION BOX
HFJ–2
Original, 05/94 NMP Part No. 0275008
HF Junction Box HFJ–2
AMENDMENT RECORD SHEET
After Sales
Technical Documentation
Amendment
Number
Date Inserted By Comments
Page 2
Original, 05/94
After Sales
Technical Documentation
HF Junction Box HFJ–2
HF JUNCTION BOX HFJ–2
CONTENTS
Page No
Introduction 5
General 5
Main Features 5
Accessories Supply Voltage 5
Audio Switches 5
Handsfree Audio Amplifiers 5
Charger 5
External I/O 5
Booster Interface 5
Modes of Operation 5
Power–off Mode 5
Power–down Mode 6
Power–on Mode 6
External Signals and Connections 6
Power Supply Connector X210 6
External Microphone X230 6
External Speaker X250 6
Accessory Connector X170 7
Phone Connector X290 7
Functional Description 8
Circuit Description 8
Control Block 8
Booster Interface 8
Charger 9
Audio Switches 10
External I/O 11
Power Supply 11
Microphone Amplifier 12
Speaker Amplifier 12
Parts List 15
Original, 05/94
Page 3
HF Junction Box HFJ–2
Technical Documentation
Assembly Parts 22
After Sales
List of Figures
Figure 1: Block Diagram 13
Figure 2: Component Layout Diagram 14
Figure 3: Exploded View 22
Figure 4: Circuit Diagram NO TAG
Page 4
Original, 05/94
After Sales
Technical Documentation
Introduction
General
The HFJ–2 Handsfree Junction Box provides and controls the supply voltages for the accessories rge current for the phone. In addition, it controls
the audio paths to the accessories and handsfree equipment.
The unit contains a protection circuit against battery voltage transients,
power switch, handsfree speaker and microphone amplifiers, audio
switches, external I/O, switch mode charger and a microprocessor which
communicates with the phone via the mbus interface.
The BABT approved version of HFJ–2 is known as HFJ–2X. Since both
units are technically identical, all references to HFJ–2 equally apply to
HFJ–2X.
HF Junction Box HFJ–2
Main Features
Accessories Supply Voltage
Filtered and switched voltages are supplied to peripheral devices and to
handsfree audio parts in the HFJ–2 box. Protection against disturbances,
such as overvoltages, transients in incoming battery voltage, is provided.
Audio Switches
Controls audio paths between phone, handsfree equipment and
accessories.
Handsfree Audio Amplifiers
External microphone and speaker amplifiers for handsfree operation.
Charger
Provides supply voltage and charge current for phone.
External I/O
Open collector output, capable of driving an external relay.
Booster Interface
When requested via mbus message, HFJ–2 can read booster tuning values from booster EEPROM and send them to the phone. Tuning values
can also be written to booster EEPROM.
Modes of Operation
Power–off Mode
The battery voltage is always connected to the accessory and charger
power switches. The rest of the circuitry does not receive supply voltages.
Original, 05/94
Page 5
HF Junction Box HFJ–2
Power–down Mode
+5 V supply voltages are switched on. The processor is in power down
mode and its clock oscillator is not running.
Power–on Mode
The processor is executing code. +5 V supply voltages are on and other
supply voltages are under processor control.
External Signals and Connections
The module is provided with five external connectors: power supply connector, external microphone connector, external speaker connector, phone
connector, and accessory connector.
Power Supply Connector X210
After Sales
Technical Documentation
Pin Name Description
1 XCRM External car radio mute: open collector output is pulled down-
when radio is muted, when radio is not muted, collector output
is in a high impedance state. The load relay should be connected between this pin (1) and +Vbat.
– on state max. voltage: +1 V
– on state max. current: 250 mA
– off state max. current: 1 mA
– load resistance min.: 64 Ω
2 IGNS Input controlling auto power off function: should be connected
to car ignition switch (after switch) when in use and to ground
when not in use.
3 GND Power supply ground: should be connected to car battery neg-
ative terminal.
4 +VBAT Power supply voltage: should be connected to car battery posi-
tive terminal.
External Microphone X230
Pin Name Description
1 GND Ground for external microphone.
2 HFMIC Supply voltage for microphone / audio signal from microphone.
External Speaker X250
Pin Name Description
1 GND Ground for external speaker.
2 HFSP Audio signal (d.c.) to speaker/speaker indication.
Page 6
Original, 05/94
After Sales
Technical Documentation
Accessory Connector X170
Pin Name Description
1 +VBS Power supply for accessories; HFJ–2 turns this voltage on and
off under phone control.
2 DGND Digital Ground.
3 M2BUS Serial mbus data between handset, HFJ–2 and accessories.
4 LSP Not Connected.
5 PWR This signal is pulled to +5 V at HFJ–2 via an internal resistor.
Indicates external handset power–on switch state to HFJ–2.
6 AGND Analog Ground.
7 MIC Audio signal from accessories to phone (transmitted audio) or
HF speaker (voice dialer phrase, answer machine message).
8 EAR Audio signal from phone (received audio) or from HF micro-
phone to accessories.
HF Junction Box HFJ–2
Phone Connector X290
Pin Name Description
1 SCL/TXI IIC bus clock for booster; this signal is pulled to +5 V at HFJ–2
via the internal resistor of the processor. This pin is also used
for booster error indication; in error condition, the booster pulls
this pin (1) down (pin 1 can be used as an output to the boost-
er at the same time). Periodically, Pin 1 is changed to input for
60 s time and TXI state is polled. These polling pulses must
be filtered in the booster.
2 PGND Ground for charger.
3 M2BUS Serial mbus data between phone, HFJ–2 and accessories.
4 VC Supply voltage/charging current for phone.
5 HOOD/SDA Handset hook ind./IIC bus data for booster.
6 SGND Signal ground.
7 XMIC/
JCONN
8 XEAR/
HFJPWR
Audio signal from accessories or HF microphone to phone:
100 kΩ pull–up to +5 V; d.c. level indicates connection of
HFJ–2 box to phone.
Audio signal from phone (received audio) to accessories or HF
speaker: 1 MΩ pull–up resistor to +VBAT, drop down of current
from this pin turns on +5 V supply to the processor.
Original, 05/94
Page 7
Loading...