Panasonic KX-TG2853BXS User manual

© 2006 Panasonic Communications Co., Ltd. All
rights reserved. Unauthorized copying and distribu-
tion is a violation of law.
ORDER NO. KM40607144CE
Telephone Equipment
KX-TG2853BXS
KX-TG2854BXS
KX-TGA280BXS
Expandable Digital Cordless Answering
System
Expandable Digital Cordless Answering
System with Two Handsets
Silver Version
(for Asia, Middle Near East and Other areas)

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
TABLE OF CONTENTS
PAGE PAGE
1 Safety Precautions----------------------------------------------- 4
1.1. For Service Technicians --------------------------------- 4
2 Warning -------------------------------------------------------------- 4
2.1. Battery Caution--------------------------------------------- 4
2.2. About Lead Free Solder (Pbf: Pb free)--------------- 4
3 Specifications ----------------------------------------------------- 6
4 Technical Descriptions ----------------------------------------- 7
4.1. Block Diagram (Base Unit) ------------------------------ 7
4.2. Circuit Operation (Base Unit)--------------------------- 8
4.3. Block Diagram (Handset)-------------------------------10
4.4. Circuit Operation (Handset)----------------------------11
4.5. Circuit Operation (Charger Unit) ----------------------14
4.6. Signal Route -----------------------------------------------15
5 Location of Controls and Components ------------------16
5.1. Controls -----------------------------------------------------16
5.2. Display ------------------------------------------------------17
6 Installation Instructions ---------------------------------------18
6.1. Connections------------------------------------------------18
6.2. Battery Installation/Replacement ---------------------19
6.3. Battery Charge --------------------------------------------19
7 Operation Instructions-----------------------------------------21
7.1. Guide to Cordless Handset Programming ---------21
7.2. Dial Lock ----------------------------------------------------23
7.3. Registering the Cordless Handset -------------------24
7.4. Canceling the Cordless Handset Registration ----24
7.5. Copying Phonebook Items -----------------------------25
7.6. Error Message---------------------------------------------25
7.7. Troubleshooting-------------------------------------------26
8 Test Mode ----------------------------------------------------------30
8.1. Test Mode Function (Base Unit) ----------------------30
8.2. Test Mode Function (Handset) ------------------------31
9 Service Mode -----------------------------------------------------32
9.1. Copying Phonebook Items When Repairing-------32
9.2. Service Mode Function (for Base Unit with
Handset) ----------------------------------------------------34
10 Troubleshooting Guide ----------------------------------------35
10.1. Troubleshooting Flowchart -----------------------------35
10.2. Troubleshooting by Symptom (Base Unit )---------40
10.3. How to Replace the Flat Package IC----------------41
11 Disassembly and Assembly Instructions ---------------43
11.1. Disassembly Instructions -------------------------------43
11.2. Fix the LCD to the Main P. C. Board (Handset) ---46
12 Measurements and Adjustments---------------------------47
12.1. Things to Do after Replacing IC ----------------------47
12.2. The Setting Method of JIG (Base Unit) -------------48
12.3. The Setting Method of JIG (Handset) ---------------50
12.4. Commands -------------------------------------------------51
12.5. Adjustment of Handset ----------------------------------52
12.6. Base Unit Reference Drawing-------------------------53
12.7. Handset Reference Drawing---------------------------54
12.8. How to Check the Speaker or Receiver ------------55
12.9. Frequency Table (MHz) ---------------------------------56
13 Schematic Diagram ---------------------------------------------58
13.1. For Schematic Diagram---------------------------------58
13.2. Schematic Diagram (Base Unit) ----------------------59
13.3. Schematic Diagram (Base Unit_Operation) -------61
13.4. Schematic Diagram (Handset) ------------------------63
13.5. Schematic Diagram (Charger Unit) ------------------65
14 Printed Circuit Board ------------------------------------------ 66
14.1. Circuit Board (Base Unit_Main) ---------------------- 66
14.2. Circuit Board (Base Unit_Operation)---------------- 68
14.3. Circuit Board (Handset) -------------------------------- 70
14.4. Circuit Board (Charger Unit)--------------------------- 72
15 Appendix Information of Schematic Diagram --------- 73
15.1. CPU Data (Base Unit) ---------------------------------- 73
15.2. CPU Data (Handset) ------------------------------------ 75
15.3. Terminal Guide of the ICs, Transistors and
Diodes ------------------------------------------------------ 77
16 Exploded View and Replacement Parts List ----------- 78
16.1. Cabinet and Electrical Parts (Base Unit)----------- 78
16.2. Cabinet and Electrical Parts (Handset)------------- 79
16.3. Cabinet and Electrical Parts (Charger Unit) ------- 80
16.4. Accessories and Packing Materials ----------------- 81
16.5. Replacement Parts List--------------------------------- 84

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
1 Safety Precautions
1.1. For Service Technicians
ICs and LSIs are vulnerable to static electricity.
When repairing, the following precautions will help prevent recurring malfunctions.
1. Cover the plastic parts boxes with aluminum foil and ground them.
2. Ground the soldering irons.
3. Use a conductive mat on the worktable.
4. Do not touch IC or LSI pins with bare fingers.
2Warning
2.1. Battery Caution
1. Danger of explosion if battery is incorrectly replaced.
2. Replace only with the same or equivalent type recommended by the manufacturer.
3. Dispose of used batteries according to the manufacture’s Instructions.
2.2. About Lead Free Solder (Pbf: Pb free)
Note:
In the information below, Pb, the symbol for lead in the periodic table of elements, will refer to standard solder or solder that con-
tains lead.
We will use PbF solder when discussing the lead free solder used in our manufacturing process which is made from Tin (Sn),
Silver (Ag), and Copper (Cu).
This model, and others like it, manufactured using lead free solder will have PbF stamped on the PCB. For service and repair
work we suggest using the same type of solder.
Caution
• PbF solder has a melting point that is 50 °F ~ 70 °F (30 °C ~ 40 °C) higher than Pb solder. Please use a soldering iron with
temperature control and adjust it to 700 °F ± 20 °F (370 °C ± 10 °C).
• Exercise care while using higher temperature soldering irons.:
Do not heat the PCB for too long time in order to prevent solder splash or damage to the PCB.
• PbF solder will tend to splash if it is heated much higher than its melting point, approximately 1100 °F (600 °C).
• When applying PbF solder to double layered boards, please check the component side for excess which may flow onto the
opposite side (See the figure below).

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
2.2.1. Suggested PbF Solder
There are several types of PbF solder available commercially. While this product is manufactured using Tin, Silver, and Copper
(Sn+Ag+Cu), you can also use Tin and Copper (Sn+Cu) or Tin, Zinc, and Bismuth (Sn+Zn+Bi). Please check the manufacturer’s
specific instructions for the melting points of their products and any precautions for using their product with other materials.
The following lead free (PbF) solder wire sizes are recommended for service of this product: 0.3 mm, 0.6 mm and 1.0 mm.
2.2.2. How to Recognize that Pb Free Solder is Used
(Example: Handset P.C.B.)
(Component View)
Note:
The location of the “PbF” mark is subject to change without notice.
IC700
IC460
IC2
IC1
IC301
PbF
1
Marked

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
3 Specifications

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
4 Technical Descriptions
4.1. Block Diagram (Base Unit)
Analog
Front
End
To TEL_LINE
CN101
A B
Bridge
Rect
D103
Hook Switch Q104, Q105 Audio
Caller ID Interface
CPU
BELL
HOOK
Off-Hook Line Voltage
D/A A/D
ADPCM
Codec Filter
DSP
Speech Decoding Speech Encoding
BMC
Burst Decoding
Burst Encoding
RF
Interface
IC701
RXDA
ANT1 ANT2
TXDA
RSSI
SYCL SYDA SYEN
RF Module
XTAL
X1
10.368 MHz
SP-AMP
IC402
Flash
Memory
IC501
To AC Adaptor
CN301
Limit
Resistor
CHARGE CONTACT
3.45V
Reg. IC301
3.0V
Reg. Q2
1.8V
Reg. Q3
3.45V
3.0V
1.8V
Bell Interface
IC1
BBIC
KX-TG2853/2854 BLOCK DIAGRAM (Base Unit)

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
4.2. Circuit Operation (Base Unit)
4.2.1. Outline
Base Unit consists of the following ICs as shown in Block Diagram (Base Unit) (P.7).
• BBIC (Base Band IC): IC1
- Handling all the audio, signal and data processing needed in a FHSS base unit
- Controlling the FHSS specific physical layer and radio section (Burst Module Controller section)
- ADPCM codec filter for speech encoding and speech decoding (DSP section)
- Echo-cancellation and Echo-suppression (DSP section)
- Any tones (tone, sidetone, ringing tone, etc.) generation (DSP section)
- DTMF receiver (DSP section)
- Clock Generation for RF Module
- ADC, DAC, timer, and power control circuitry
- All interfaces (ex: RF module, LED, Analog Front End, etc.)
• RF Module: IC701
- Transceiver IC including LNA, PLL, demodulator, logic
- PA (TX power amplifier)
• FLASH MEMORY: IC501
- Voice Prompt (TAM) D/L Area
• Additionally
- Power Supply Circuit (+3.45V, +3.0V, +1.8V output)
- Crystal Circuit (10.368MHz)
- Charge Circuit
- Telephone Line Interface Circuit
4.2.2. Power Supply Circuit
The power is supplied to the Base Band IC, RF Module and Charge Contact from AC Adaptor (+6.5V) as shown in Fig.101. The
power supply is as follows:
• Base Band IC (IC1):
CN301 (+6.5V) →IC301 →Q2 →IC1
• RF Module (IC701):
CN301 (+6.5V) →IC301 →Q2 →IC701 (PLL)
CN301 (+6.5V) →IC301 →IC701 (Power AMP)
• FLASH MEMORY (IC501):
CN301 (+6.5V) →IC301 →Q2 →IC501
• Charge Contact (TPCHGP):
CN301 (+6.5V) →R304, R305, R309, R310 →TPCHGP
<Fig.101>

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
4.2.3. Telephone Line Interface
<Function>
• Bell signal detection
• Clip signal detection
• ON/OFF hook circuit
• Audio circuits
• DTMF tone signal circuits
Bell signal detection:
In the standby mode, Q104 is open to cut the DC loop current and decrease the ring load.
When ring voltage appears at the TP L1T (A) and TP L1R (B) leads (When the telephone rings), the AC ring voltage is trans-
ferred as follows;
•A→R144 →C144 →Q146 →IC1 Pin 98 (RINGING)
•B→R145 →C145 →Q146 →IC1 Pin 98 (RINGING)
Clip (: Calling Line Identification Presentation: Caller ID) signal detection:
The Clip signal voltage is transferred as follows;
•A→C121 →R123 →R128 →IC1 Pin 112 (CIDinn)
•B→C131 →R133 →R138 →IC1 Pin 107 (CIDinn)
ON/OFF hook circuit:
In the standby mode, Q104 is open, and connected as to cut the DC loop current and to cut the voice signal. The unit is conse-
quently in an on-hook condition.
When IC1 detects a ring signal or press the TALK Key onto the handset, Q105 turns on and Q104 turns on, thus providing an
off-hook condition (active DC current flow through the circuit) and the following signal flow is for the loop current.
•A→D103 →Q104 →Q171 →R178 →R179 →D103 →B [OFF HOOK]
4.2.4. Transmitter/Receiver
Base Unit and Handset mainly consist of RF Module and BBIC.
Base Unit and Handset transmit/receive voice signal and data signal through the antenna on carrier frequency.

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
4.3. Block Diagram (Handset)
Receiver
RF_UNIT
IC700
ANT
X1
10.368 MHz
EEPROM
IC2
LCD
Speaker
Charge Control
Q500
Q501
Q502
LCD_Light
LED2, 3, 4
Q101
D501
ANT_LED
KEY_Light
LED5, 6, 7, 8, Q100
Power Circuit
IC300, IC301
Q300, Q301, Q302
MIC
Charge
Battery
+
+
-
-
BBIC
IC1
KEYS
KX-TGA280 BLOCK DIAGRAM (Handset)

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
4.4. Circuit Operation (Handset)
4.4.1. Construction
The circuit mainly consists of DSP and RF part as shown in the block diagram.
4.4.1.1. BBIC: IC1
Function:
• Battery Low, Power down detect circuit
• Ringer Generation
• Interface circuit (RF part, Speaker, Mic, LED, Key scan, LCD)
Initial waves:
4.4.1.2. RF part
Mainly voice signal is modulated to RF, or it goes the other way.
4.4.1.3. EEPROM: IC2
ALL setting data is stored.

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
4.4.2. Power Supply Circuit
Circuit Operation:
When power on the handset, the voltage is as follows;
BATTERY (2.2 V ~ 2.6 V: J1) →L502 →L300, D300 →Q300 (3.4 V) →Q302 (1.8 V), Q301 (2.5 V)

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
4.4.3. Charge Circuit
Circuit Operation:
When charging the handset on the charger unit, the charge current is as follows;
DC+ (6.5V) →R304, R305, R309, R310 →CHARGE+ (Base) →CHARGE+ (Handset) →Q502 →D501 →L502 →
BATTERY+ --- Battery --- BATTERY- →L503 →GND →R504 →CHARGE- (Handset) →CHARGE- (Base) →GND →
DC- (GND)
In this way, the BBIC on handset detects the fact that the battery is charged.
The charge current is controlled by switching Q500 of handset.
4.4.4. Ringer and Handset SP-phone

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
4.4.5. Sending Signal
4.4.6. Battery Low/Power Down Detector
Circuit Operation:
“Battery Low” and “Power Down” are detected by BBIC which check the voltage from battery.
The detected voltage is as follows;
• Battery Low
Battery voltage: V (Batt) < 2.3V ± 50mV
The BBIC detects this level and “ ” starts flashing.
• Power Down
Battery voltage: V (Batt) < 2.1V ± 50mV
The BBIC detects this level and power down.
4.5. Circuit Operation (Charger Unit)
4.5.1. Power Supply Circuit
The power supply is as shown.

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
4.6. Signal Route

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
5 Location of Controls and Components
5.1. Controls
5.1.1. Base Unit

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
5.1.2. Cordless Handset
5.1.3. Charger
5.2. Display

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
6 Installation Instructions
6.1. Connections

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
6.2. Battery Installation/
Replacement
6.3. Battery Charge

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KX-TG2853BXS/KX-TG2854BXS/KX-TGA280BXS
6.3.1. Battery Strength
6.3.2. Recharging the Battery
6.3.3. Battery Performance