Panasonic KX-TCD953RUB (serv.man2) Service Manual ▷ View online
9.1.6. CLOCK GENERATION (SEE Fig. 28)
A single clock generator in the BBIC uses an external crystal X1 to derive all clock frequencies used in the handset. The crystal is
tuned to the exact frequency of 10.368 MHz during manufacture by feeding a DC voltage from an internal DAC (from pin 12) to the
varicap diode D12 (TP25). The RFCLK output (pin 10, TP56) is a buffered clock signal at 10.368 MHz for the Frequency
Synthesizer, that is only active during the PLL lock period (see section 1.3). The basic data rate for TX-DATA and RX-DATA is
1.152 Mbits/s, which is divided by 9. The data rate for the serial interface to the phase-lock-loop is also 1.152 Mbits/s.
tuned to the exact frequency of 10.368 MHz during manufacture by feeding a DC voltage from an internal DAC (from pin 12) to the
varicap diode D12 (TP25). The RFCLK output (pin 10, TP56) is a buffered clock signal at 10.368 MHz for the Frequency
Synthesizer, that is only active during the PLL lock period (see section 1.3). The basic data rate for TX-DATA and RX-DATA is
1.152 Mbits/s, which is divided by 9. The data rate for the serial interface to the phase-lock-loop is also 1.152 Mbits/s.
9.1.7. KEYBOARD (SEE Fig. 28)
The keyboard “On” button is connected directly to pin 41 of the BBIC (TP10). When pressed it turns the handset on and off (must
be held for off). All other keys are connected in a row/column matrix. They are scanned in six rows using scan pulses (only active
when keys are pressed) from IC1 pins 28 to 33. The four key matrix columns are input to the BBIC on pins 31 to 34.
be held for off). All other keys are connected in a row/column matrix. They are scanned in six rows using scan pulses (only active
when keys are pressed) from IC1 pins 28 to 33. The four key matrix columns are input to the BBIC on pins 31 to 34.
Circuit Diagram
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KX-TCD953RUB
9.1.8. FACTORY SERIAL PORT (SEE Fig. 25)
In order to communicate with the handset during manufacture and servicing (using a PC) a serial data link has been provided.
Serial data input/output is provided on J6 (TP65), and a ground is provided on J7. The bi-directional serial data line is split into two
at IC1 pin 27 (input) and pin 26 (output). Data rate is 9600 baud or 115.2 kBaud. D13 provides ESD protection, and R37 and C56
provide RF de-coupling.
Serial data input/output is provided on J6 (TP65), and a ground is provided on J7. The bi-directional serial data line is split into two
at IC1 pin 27 (input) and pin 26 (output). Data rate is 9600 baud or 115.2 kBaud. D13 provides ESD protection, and R37 and C56
provide RF de-coupling.
9.1.9. BUZZER CIRCUIT (SEE Fig. 29)
A square-wave signal from IC1 pin 45 is used to sound the buzzer via switching transistor T5 (TP22). Various tones and cadences
are used dependent on function. Buzzer volume is varied by changing the duty cycle of the drive waveform. D11 provides
quenching of back-emf generated when T5 turns off.
are used dependent on function. Buzzer volume is varied by changing the duty cycle of the drive waveform. D11 provides
quenching of back-emf generated when T5 turns off.
9.1.10. BATTERY SUPPLY (SEE Fig. 29)
The three cell NiCd/NiMH rechargeable battery supplies the handset via 2A fuse (actually a coil), and is de-coupled by C3 and C4.
It directly supplies T3 in the baseband section, and also the Tx PA in the RF Section. It also supplies IC1 (de-coupled by C9), and
most of the RF Section (VCC-OC) (decupled by R35 and C47, C48 and VCC-PA).
It directly supplies T3 in the baseband section, and also the Tx PA in the RF Section. It also supplies IC1 (de-coupled by C9), and
most of the RF Section (VCC-OC) (decupled by R35 and C47, C48 and VCC-PA).
9.1.11. MAIN 3V REGULATOR (SEE Fig. 29)
The BBIC measures the battery voltage on pins 58 using an internal ADC. If the battery voltage is below 3.36 V, TC3 is switched
to power off mode. R7 and C5 provide a reset pulse (TP84) used for resetting the BBIC when power on. The +3 V supply (TP10)
is fed to the BBIC, Flash PROM, EEPROM, and Display Driver.
to power off mode. R7 and C5 provide a reset pulse (TP84) used for resetting the BBIC when power on. The +3 V supply (TP10)
is fed to the BBIC, Flash PROM, EEPROM, and Display Driver.
9.1.12. BATTERY CHARGING CIRCUIT (SEE Fig. 29)
The charge circuit is designed to operate with a constant current charger in the base. L1, L2, D2 and D4 protect against electro-
static discharge (ESD). The charging current from the base is turned on and off by T1 using a control signal from the BBIC (pin 39,
TP6) via T2. R3 provides initial current in the event of a totally flat battery, and D6 protects against the high voltage present on the
charge contacts if there is no battery in the handset. R4 and R5 provide a signal for the BBIC to detect (pin 40) that the handset
had been placed on the base charger. If the handset is off, it will be switched on, and charging will start. D2, D3, D4, and D5 act
as steering diodes to enable the handset to be placed on the cradle either way up (i.e. the handset is reversible).
static discharge (ESD). The charging current from the base is turned on and off by T1 using a control signal from the BBIC (pin 39,
TP6) via T2. R3 provides initial current in the event of a totally flat battery, and D6 protects against the high voltage present on the
charge contacts if there is no battery in the handset. R4 and R5 provide a signal for the BBIC to detect (pin 40) that the handset
had been placed on the base charger. If the handset is off, it will be switched on, and charging will start. D2, D3, D4, and D5 act
as steering diodes to enable the handset to be placed on the cradle either way up (i.e. the handset is reversible).
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KX-TCD953RUB
Circuit Diagram
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KX-TCD953RUB
Adjustment objectives
10 ADJUSTMENT (BASE UNIT)
Adjustment item
Symptom
Remedy
Clock frequency
Synchronization with the portable handset is lost immediately.
Perform the adjustments described in item(1).
No link is established.
Tools required for adjustments
•
Frequency counter
•
Personal computer
•
Serial communication tool
•
Test software (batch files)
•
Line simulator
•
Oscilloscope
•
Audio level meter
Item(1)
1. Connect the serial link to test computer to J102 (serial data) and J103 (GND).
2. Connect the AC adaptor.
3. Connect the frequency counter to TP148 (SCLK) and J103 (GND).
4. Send “SETFREQ.BAT” to set the clock frequency. The default value is 80. Increase the value to increase the frequency. The
clock frequency must be 3,456 kHz ± 0.007 kHz.
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KX-TCD953RUB
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