Panasonic KX-TD7685 - Wireless Digital Phone User manual

© 2008 Panasonic Communications Co., Ltd. All
rights reserved. Unauthorized copying and distribu-
tion is a violation of law.
ORDER NO. KMS0802461CE
F19
DECT6.0 Portable Station
KX-TD7685
(for U.S.A.)

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KX-TD7685
TABLE OF CONTENTS
PAGE PAGE
1 Safety Precautions -----------------------------------------------3
1.1. For Service Technicians ----------------------------------3
1.2. Caution--------------------------------------------------------3
1.3. Battery Caution ---------------------------------------------3
2Warning--------------------------------------------------------------3
2.1. About Lead Free Solder (PbF: Pb free) --------------3
3 Specifications ------------------------------------------------------4
4 Technical Descriptions------------------------------------------5
4.1. Block Diagram (Handset) --------------------------------5
4.2. Circuit Operation (Handset) -----------------------------6
5 Location of Controls and Components------------------ 11
5.1. Handset----------------------------------------------------- 11
6 Installation Instructions--------------------------------------- 13
6.1. Connection and Setting--------------------------------- 13
6.2. Battery ------------------------------------------------------ 13
7 Test Mode ---------------------------------------------------------- 15
7.1. Required Equipment------------------------------------- 15
7.2. Initial Setting----------------------------------------------- 15
7.3. Command Reference ----------------------------------- 16
8 Service Mode ----------------------------------------------------- 24
8.1. Software Upload ----------------------------------------- 24
9 Troubleshooting Guide---------------------------------------- 29
9.1. Power Trouble (Handset) ------------------------------ 29
9.2. Battery Charge Trouble (Handset)------------------- 30
9.3. LED Trouble (Handset) --------------------------------- 32
9.4. Vibrator Trouble (Handset) ---------------------------- 33
9.5. Ringer Trouble (Handset) ------------------------------ 33
9.6. Key Click Sound Trouble (Handset) ----------------- 34
9.7. No Link Trouble ------------------------------------------ 35
9.8. No Voice Transmission --------------------------------- 36
9.9. No Voice Reception-------------------------------------- 37
9.10. Password Trouble---------------------------------------- 38
9.11. Things to Do After Replacing Main Board /
BBIC--------------------------------------------------------- 39
10 Disassembly and Assembly Instructions -------------- 40
10.1. Handset ---------------------------------------------------- 40
10.2. Charger----------------------------------------------------- 42
11 Measurements and Adjustments-------------------------- 43
11.1. Adjustment for Main Part (Handset) ---------------- 43
11.2. Adjustment for RF Part (Handset) ------------------- 46
11.3. Frequency Table ----------------------------------------- 54
12 Miscellaneous --------------------------------------------------- 55
12.1. Terminal Guide of ICs, Transistors and diodes--- 55
12.2. How To Replace a Flat Package IC----------------- 56
13 Schematic Diagram -------------------------------------------- 58
13.1. Handset ---------------------------------------------------- 58
13.2. Charger----------------------------------------------------- 62
14 Printed Circuit Board------------------------------------------ 63
14.1. Handset(Main)-------------------------------------------- 63
14.2. Charger Board-------------------------------------------- 64
15 Appendix Information of Schematic Diagram -------- 65
16 Exploded View and Replacement Parts List----------- 66
16.1. CPU Data -------------------------------------------------- 66
16.2. Cabinet and Electrical Parts Location -------------- 69
16.3. Accessories and Packing Materials----------------- 71
16.4. Replacement Parts List -------------------------------- 72

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KX-TD7685
1 Safety Precautions
1.1. For Service Technicians
•Repair service shall be provided in accordance with repair technology information such as service manual so as to pre-
vent fires, injury or electric shock, which can be caused by improper repair work.
1. When repair services are provided, neither the products nor their parts or members shall be remodeled.
2. If a lead wire assembly is supplied as a repair part, the lead wire assembly shall be replaced.
3. FASTON terminals shall be plugged straight in and unplugged straight out.
•ICs and LSIs are vulnerable to static electricity.
When repairing, the following precautions will help prevent recurring malfunctions.
1. Cover plastic parts boxes with aluminum foil.
2. Ground the soldering irons.
3. Use a conductive mat on worktable.
4. Do not grasp IC or LSI pins with bare fingers.
1.2. Caution
When you operate this unit, the AC outlets should be near the unit and easily accessible.
1.3. Battery Caution
Danger of explosion if the battery is replaced incorrectly. Replace only with the same or equivalent type recommended by the
manufacturer. Dispose of used batteries according to the manufacture’s Instructions.
2Warning
2.1. 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 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°~ 70°F, ( 3 0°~ 40°C) higher than Pb solder. Please use a soldering iron with tempera-
ture control and adjust it to 700°± 20°F, ( 3 7 0°± 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 figure, below).

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KX-TD7685
2.1.1. 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 manufac
turer'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: 0.3mm, 0.6mm and 1.0mm.
3 Specifications

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4 Technical Descriptions
4.1. Block Diagram (Handset)

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4.2. Circuit Operation (Handset)
4.2.1. Outline
Handset consists of the following ICs as shown in 4.1. Block Diagram (Handset).
•BBIC (Base Band IC): IC201
-All data signals (forming/analyzing ACK or CMD signal)
-All interfaces (ex: Key, Detector Circuit, Charge, LCD)
Include EEPROM and Flash memory
EEPROM stores the temporary operating parameters (for RF, etc.)
•AMPLIFIER IC: IC401
-Single OP_AMP for SPEAKER
•MIDI: IC301
-16-Tone 32-Poly PCM Sound Generator
-Port (LED direct driver with PWM)
•RF Module: IC601
-PLL Oscillator
-Detector
-Compress/Expander
-Amplifier for reception
-Amplifier for transmission
-Power control
4.2.2. Power Supply Circuit/Reset Circuit
When power on the Handset, the voltage is as follows;
BATTERY(3.5 V to 4.2V: Battery+) →Q104 (1.8V) →Q105 (2.7V)
The Reset signal generates pin 78 of IC201 and 1.8V.
3.1V for IC601 is generated with IC602.
5.0V for Key back-light and LCD back-light is generated with IC302.
Battery(3.5V to 4.2V) is used for RF Module (IC601), Amplifier IC (IC401), Vibrator, DC/DC Converter (IC302).
1.8V is used only for BBIC (IC201).
2.7V is used for BBIC (IC201), LCD, MIDI (IC301), INVERTER (LOGIC IC (IC303)), Red LED, Green LED.

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4.2.3. Charge Circuit (Include Charger)
When charging the handset on the charger, Q1 of charger is turned on and battery charging starts, the charge current is as fol-
lows;
DC+(6.5V) →L1 →Q1 →R3 →JT1(Charger) →JT101(Handset) →L101 →Q101→D102→L104 →BATTERY+ ... Battery ...
BATTERY- →GND →R115 →L102→JT102(Handset) →JT2(Charger) →R4 →R2 and R5 →GND
In this way, the BBIC on Handset detects the fact that the battery is charged.
The charge current is controlled by switching Q101 of Handset.
When charging is completed, the BBIC (IC201) of the handset sets the base of Q103 to "High", then Q102 is turned OFF. As a
result, the charging stops.
4.2.4. Battery Low/Power Down Detector
"Battery Low" and "Power Down" are detected by BBIC (IC201) which check the voltage from battery.
The detected voltage is as follows;
•Battery Low
Battery voltage: V(Batt) 3.5V ± 50mV
The BBIC detects this level and " " starts flashing.
•Power Down
Battery voltage: V(Batt) 3.3V ± 50mV
The BBIC detects this level and power down.
4.2.5. TX Audio Path
Microphone
An audio signal from microphone is input to pin 76 (MIC+) of IC201 via headset jack (CN404).
In IC201, the audio signal is converted from the analog signal to ADPCM, then to burst data, and sent from pin 19 (TXDA) to RF
Module (IC601). The stabilized supply voltage is fed to the microphone. From pin 77 (VREF+) of IC201.
To reduce consumption current, this voltage is supplied only while calling or receiving.
Headset
When a headset is inserted, a signal from microphone is cut off and an audio signal from a headset is input to pin 76 (MIC+).
Headset detection
When a headset is inserted, pin 23 (ADC2) of IC201 goes from High (around 1V) to Low and BBIC (IC201) detects the insertion
of the headset.

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KX-TD7685
4.2.6. RX Audio Path
Receiver
Burst data is input from RF Module (IC601) to pin 17 (RXDA) of IC201.
In IC201, the burst data is converted to ADPCM, then to analog signal, and sent from pin 68 (LSR+) and pin 69 (LSR-) to the
receiver.
Headset
When the headset is inserted, a signal to the receiver is cut off and audio signal from pin 68 (LSR+) of IC201 is input to the
headset.
Speakerphone
In Speakerphone mode, the BBIC (IC201) makes pin 1 of IC401 from Low to High.
And an audio signal from pin 70 (LSR_HS) of IC201 is sent to a monitor speaker through speaker Amplifier IC (IC401).

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4.2.7. LCD Circuit
The LCD is controlled by 3 control signal (SCL1, P2-1, P3-7) and SERIAL data (SDA1) of IC201.
4.2.8. LED Circuit
BBIC (IC201) controls each LED through MIDI (IC301).
Type of LED LED ON LED OFF
IC301 Transistor IC301 Transistor
Call/Charge indicator LED (green), D302 pin 34 = high Q302 = ON pin 34 = low Q302 = OFF
Call/Charge indicator LED (red), D301 pin 33 = high Q301 = ON pin 33 = low Q301 = OFF
LCD back-light LED (blue), D305-D307
Key back-light LED (blue), D308-D311 pin 31 = low Q304 = OFF pin 31 = high Q304 = ON

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4.2.9. Ringer Circuit
During ringing, a signal is sent from pin 10 and pin 11 of IC301 to a monitor speaker through speaker Amplifier IC (IC401). At this
time, BBIC (IC201) makes pin 1 of IC401 from low to high.
4.2.10. Key Click Sound Circuit
When the key is pushed, a signal is sent from pin 45 of IC201 to a monitor speaker through speaker Amplifier IC (IC401). At this
time, BBIC (IC201) makes pin 1 of IC401 from low to high.
4.2.11. Vibrator Circuit
BBIC (IC201) controls Vibrator through MIDI (IC301).
Pin 37 (VIB) of IC301 goes low and Vibrator turns ON.

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5 Location of Controls and Components
5.1. Handset

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6 Installation Instructions
6.1. Connection and Setting
6.1.1. Charger Connection
• The AC adaptor should be connected to a vertically oriented
or floor-mounted AC outlet. Do not connect the AC adaptor
to a ceiling-mounted AC outlet, as the weight of the adaptor
may cause it to become disconnected.
6.2. Battery
6.2.1. Battery Installation
Insert the battery, and close the cover as indicated below.
6.2.2. Battery Charge
At the time of shipment, the battery is not charged.
Please charge the battery for about 7 hours before using the handset for the first time.
• When the battery has been completely charged, the charge indicator will change from red to green.
• It is normal for the handset and charger to feel warm while the battery is charging.

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6.2.3. Battery Life
After your Panasonic battery is fully charged [at 25°C (77°F)]:
• Operating time may be shortened depending on usage conditions and ambient temperature.
• The battery will drain slowly even while the unit is turned off.
• The handset can receive calls while charging.
• Battery consumption increases when the handset is used out of range. If “ “ flashes, power off the handset.
6.2.4. Low Battery Warning
The battery needs to be charged in the following situations:
• “ “ flashes and the alarm sounds.*
• “Charge Battery” is displayed. In this situation, the handset cannot be operated.
* If the low battery warning occurs during a conversation, the call will be disconnected automatically one minute later.
6.2.5. Replacing the Batteries
• If “ “ flashes after using the phone for a short time, even when the battery has been fully charged, the battery should be
replaced.
Before replacing the battery, make sure the low battery warning is displayed, then turn off the power to prevent memory loss.
Replace the battery, and charge the new battery for at least 7 hours.
If you replace the battery before the low battery warnings appears, the battery strength icon may display an incorrect reading. In
this case, use the handset as normal with the new battery installed. When the low battery warning is displayed, charge the bat-
tery for about 7 hours. The battery strength icon will then display the correct reading.
1. Turn the power off to prevent memory loss.
2. Press the notch on the cover firmly and slide it as indicated by the arrow.
3. Open the cover and replace the battery.
4. Close the cover and charge the handset.
Please use a Panasonic batteries with the service part number N4HHGMB00005 or HHR-P103.
Operation Operating Time
While in use (TALK) Up to about 10 h
While not in use (Standby) Up to about 168 h

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7 Test Mode
7.1. Required Equipment
1. Personal Computer with serial port.
2. RS-232C cable for Handset (PSZZ1TD7896M).
3. Maintenance software for PC (PSZZ3TD7896M).
7.2. Initial Setting
1. Connect the handset with your PC with the RS-232C cable.
2. Copy the Maintenance software (FlashProgram.exe) from Floppy Disk to your PC and double click the FlashProgram.exe to
start the program. Then, following screen appears.

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KX-TD7685
3. Set communication environment
Click “Config” and configure as follows:
Click “OK”.
Selected items will be stored.
7.3. Command Reference
7.3.1. Select From Command Menu
- Example of Operation -
1. Click [test command] tag.

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2. Click [ Command menu ] button and select the command that you want execute. (in case of test command "EPW")
3. Set parameters if necessary.

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4. Click [send] button.
Maintenance Window is generated, and transmitted command and parameters are displayed.
Then receive data from the Handset is displayed.
- Operation of each test command -
A) Test Command "VDD control (VDD)"
1.Click [Command menu] button.
2.Point [battery].
3.Click [VDD control (VDD)].
4.Set the value ("00"-"0F") to the first parameter.
5.Click [Send] button.
(if returned value is "OK", It succeeded. )
B) Test Command "RFC clock (RFC)"
1.Click [Command menu] button.
2.Point [clock].
3.Click [RF clock (RFC)].
4.Set "1" (ON) to the first parameter.
5.Click [Send] button.
(if returned value is "OK", It succeeded. )
C) Test Command "frequency trimming (SFR)"
1.Click [Command menu] button.
2.Point [clock].
3.Click [frequency trimming (SFR)].
4.Set the value to the first parameter.
5.Click [Send] button.
(if returned value is "OK", It succeeded. )

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D) Test Command "AD1"
1.Click [Command menu] button.
2.Point [battery].
3.Click [VBAT1 read (AD1)].
4.Click [Send] button.
(if returned value is "OK", It succeeded. )
E) Test Command "loopback mode (PP)"
1.Click [Command menu] button.
2.Point [RF].
3.Point [test mode].
4.Click [loopback mode (PP)].
5.Set RFPI(5byte) to the first parameter.
(RFPI should be same as the value input to the instrument)
6.Click [Send] button.
((If returned value is "OK", it succeeded.)
F) Test Command "RSSI read (RSS)"
1.Click [Command menu] button.
2.Point [RF].
3.Click [RSSI read (RSS)].
4.Click [Send] button.
(Returned value are RSSI value and number of frame error)
G) Test Command "eeprom write (EPW)"
1.Click [Command menu] button.
2.Point [memory access].
3.Click [eeprom write (EPW)].
4.Set parameters as follows.
•First parameter: address No. (2 byte)
•Second parameter: Length ("1"-"10"(Hex))
•Third parameter: Data
5.Click [Send] button.
(Returned value is data you wrote. )
H) Test Command "set modulation (SMR)"
1.Click [Command menu] button.
2.Point [RF].
3.Click [set modulation (SMR)].
4.Set first parameter "25" as a provisional value.
5.Click [Send] button.
(Returned value is data you wrote.)
*Please adjust this value until the modulation reaches a value closest to ± 375kHz.
I) Test Command "PS ID write(IDW)"
1.Click [Command menu] button.
2.Point [RF].
3.Click [PS ID write(IDW)].
4.Set ID of Handset (5 byte) to the first parameter.
ID for Service
1DFFF0xxxx (xxxx-0000~1FFF)
Manage well so that there’s no overlap on PSID.
5.Click [Send] button.
(if returned value is "OK", It succeeded.)

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J) Test Command "PS ID read(IDR)"
1.Click [Command menu] button.
2.Point [others].
3.Click [PS ID read (IDR)].
4.Click [Send] button.
(Returned value is ID of Handset.)
K)Test Command "software version (VER)"
1.Click [Command menu] button.
2.Point [others].
3.Click [software version (VER)].
4.Click [Send] button.
(Returned value is software Version.)
L) Test Command "eeprom initialize(EPD)"
1.Click [Command menu] button.
2.Point [memory access].
3.Click [eeprom initialize(EPD)].
4.Set the value "F" to first parameter.
5.Click [Send] button.
(if returned value is "OK", It succeeded.)
M) Test Command "memory write(WRT)"
1.Click [Command menu] button.
2.Point [memory access].
3.Click [memory write(WRT)].
4.Set parameters as follows.
•First parameter: address No. (2 byte)
•Second parameter: Length ("1" -"10"(Hex) )
•Third parameter: Data
5.Click [Send] button.
(Returned value is data you wrote.)