Toshiba FT 8901A Service Manual

FILE NO. 2BO-200113

SERVICE MANUAL

CORDLESS TELEPHONE

FT-8901A

PUBLISHED IN JAPAN, Oct., 2001

SAFETY PRECAUTIONS ...................................................................................................................... 1

OPERATING CONTROLS .....................................................................................................................2

ANSWERING MACHINE ....................................................................................................................... 3

ALIGNMENT PROCEDURE .................................................................................................................. 4

BLOCK DIAGRAMS ............................................................................................................................... 8

SCHEMATIC DIAGRAMS ....................................................................................................................10

TROUBLESHOOTING HINTS ............................................................................................................. 16

IC AND TRANSISTOR VOLTAGE CHART ......................................................................................... 23

SEMICONDUCTOR LEAD IDENTIFICATION ..................................................................................... 29

ELECTRICAL PARTS LOCATION ...................................................................................................... 31

WIRING DIAGRAMS............................................................................................................................ 34

EXPLODED VIEW AND MECHANICAL PARTS LIST ........................................................................ 36

PARTS LIST......................................................................................................................................... 38

ASSEMBLY PARTS LIST ....................................................................................................................55

SPECIFICATIONS ............................................................................................................................... 56

SAFETY PRECAUTIONS

Before returning any models to the customer, a safety check of the entire instrument should be made. The service technician must be sure that no protective device built into the instrument by the manufacturer has become defective or inadvertently degraded during servicing.

1. WARNING:

Alterations of the design or circuitry of these models should not be made. Any design changes or additions such as, but not limited to, circuit modifications, auxiliary speaker

jacks, switches, grounding, active or passive circuitry, etc. may alter the safety characteristics of these models and potentially create a hazardous situation for the user.

Any design alterations or additions will void the manufacturer’s warranty and will further relieve the manufacturer of responsibility for personal injury or property damage resulting therefrom.

2. PRODUCT SAFETY NOTICE

Many electrical and mechanical parts in this chassis have special characteristics. These characteristics often pass unnoticed and the protection afforded by them cannot necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts that have these special safety characteristics are identified in this manual and its supplements; electrical components having such features are identified by a any of these components, read the parts list in this manual carefully. The use of substitute replacement parts that do not have the same safety characteristics as specified in the parts list may create shock, fire or other hazards.

in the schematic diagram and the parts list. Before replacing

— 1 —

OPERATING CONTROLS

HANDSET CONTROLS AND FUNCTIONS

Antenna

TALK

TALK/BATT LOW LED

TALK Button

(TONE MODE) Button

MEM (Memory) Button

MUTE Button

/ BATT LOW

COMPANDOR NOISE REDUCTION

RLD/P

TALK

ABC

GHI

JKL

PQ RS

TUV

TONE

OPER

MEM

MUTE

RDL/P (Redial/Pause)Button

FLASH

DEF

MNO

VOL/RING

FLASH Button

Dialpad

VOL/RING Button CH (Channel)Button

SETTING THE DIAL MODE

1 Press and hold

2 To set the dial mode for pulse dialing,

(PULSE MODE) Button

FLASH

until you hear

a confirmation tone.

press tone dialing press

. Or to set the dial mode for

. A confirmation tone sounds to indicate the setting is complete.

Charging Contacts

BASE UNIT CONTROLS AND FUNCTIONS

DC IN 9V Jack

TEL LINE Modular Jack

COMPANDOR NOISE REDUCTION

POWER LED

IN USE LED

CHARGE LED

MENU Button

SET Button

REW REPEAT/SELECT

Button

GREETING Button

POWER

IN USE

CHARGE

SET

SELECT SELECT

GREETING

ALL DIGITAL ANSWERING SYSTEM

CORDLESS TELEPHONE

PAG E

MEMO/2WAY

Rechargeable Battery Pack(back)

REC

VOLUME

TIME

Antenna

PAGE Button REC MEMO/2WAY Button

ANSWER Button

VOLUME Button VOLUME Button

SKIP FF/SELECT Button PLAY/STOP Button

Charging Contacts

MIC

— 2 —

TIME Button DELETE Button

SETTING THE CLOCK

1. Press

twice, then press

ANSWERING MACHINE

SET

2. Select the day of the week by pressing

SET

SELECT

press

3. Select the hour by pressing

SET

4. Select the minute by pressing press

5. Select AM/PM by pressing

SELECT

. When the correct day is announced,

. When the correct hour is announced, press

SELECT

. When the correct minute is announced,

. When AM or PM is announced, press

RECORDING AND SETTING THE GREETING MESSAGE

To record the greeting message:

1. Press

once, then press

2. Start to record your message after the guidance.

3. Press

REC MEMO/2WAY

To change the greeting message:

1. Press

2. Press

GREETING

SELECT

REC MEMO/2WAY

PLAY/STOP

to finish recording.

to change to other.

SET

3. Press

PLAY/STOP

to exit the system.

SETTING THE SECURITY CODE (PIN):

1. Press

2. Press

3. Press

4. Press

three times.

SET

to change the security code (PIN).

SELECT

SET

to set the security code (PIN).

SELECT

until the desired number appears.

— 3 —

ALIGNMENT PROCEDURE

Base Unit

Transmitter Section

Connections

Power

Meter

Frequency

Counter

Deviation

Meter

Test Point

RF Test Point

Preset

Press and hold the “ANSWER” key about 5.0 seconds while turning the 7 SEG LED shows “8” .

Alignment Procedure

BASE Unit

J2 DC IN 9V Jack

TEL Line

Jack

1kHz -10.5dBm

AF GEN.

Adapter

AC 120V 60Hz

step

Adjustment

RT1

(TX Power)

CT1

(TX Frequency)

Connect the Power Meter to the RF test point on the Base MAIN PCB. Adjust RT1 for a -5.0dBm reading on the Power Meter.

Connect the Frequency Counter to the RF test point on the Base MAIN PCB. Adjust CT1 to make sure that the frequency is 926.897468 MHz.

Press the “SKIP / FF” key to enter the TEST MODE “9”. Connect the AF

RT2

(TX Modulation)

Generator to the TEL Line Jack on the Base Main PCB. Make sure that the output is 1 kHz -10.5dBm from the AF Generator. Connect the Deviation Meter to the RF test point on the Base MAIN PCB. Adjust RT2 to indicate ±8 kHz Dev.

Alignment Point Location on Base Main PCB

Base Main PCB

Remarks

J1 TEL LINE Jack

J2 DC IN 9V Jack

RT2

CT1

RT1

RF Test Point

— 4 —

Receiver Section Connections

RF SG

RF Test Point

TEL Line

Jack

Dummy Load

(600-ohm)

AC VoltmeterBASE Unit

AC 120V

60Hz

Adapter

DC IN 9V Jack

AF Test Point

DC Voltmeter

Preset

Place the Base Unit in RX SENS mode (step 11) in accordance with the precedure on page 4.

Alignment Procedure

step

Preset to

SG: 1mV

No modulation

SG: 1mV

1 kHz ±8kHz

deviation

SG: -6.0dBµV

No modulation

Adjustment

L15

(Discriminator

Voltage)

RT4

(RX AF

Voltage)

RT3

(SQ Point)

Remarks

Connect the RF Signal Generator to the RF test point on the Base MAIN PCB. Make sure that the frequency is 902.952467 MHz. Connect the DC Voltmeter to the AF test point. Adjust L15 to indicate DC 2.00 V.

Connect the AC Voltmeter across a 600-ohm dummy to the Telephone Line Jack. Adjust RT4 for a -11dBm reading on the AC voltmeter.

Press the “SKIP / FF” key to enter the TEST Mode 12. Make sure that the frequency of RF SG output is 902.952467 MHz. Adjust RT3 to turn to the point where the LED indication is just vibrated.

Alignment Point Location on Base Main PCB

Base Main PCB

RT3

RT4

L15

AF Test Point

J1 TEL LINE Jack

J2 DC IN 9V Jack

RF Test Point

— 5 —

Handset Unit

Transmitter Section

Connections

Power

Meter

Frequency

Counter

Deviation

Meter

RF Test Point

HANDSET Unit

J601 Battery Connector

MIC+Pin

DC 3.8V

AF GEN.

1kHz 9mV

DC Power Supply

Preset

a) Connect DC power supply to battery connector on the handset unit. b) Turn the DC power supply ON while pressing “ ∗ ” and “ # ” keys, and keep pressing the keys continuously for

approximate 2 seconds.

c) Release keys when entering TEST mode 1 with TALK LED lighting and beep.

Alignment Procedure

step

Adjustment

RT601

(TX Power)

CT601

(TX Frequency)

RT602

(TX Modulation)

Remarks

Connect the RF power Meter to the RF test point on the handset MAIN PCB. Adjust RT601 for a -5.0dBm reading on the Power Meter.

Connect the Frequency Counter to the RF test point on the handset MAIN PCB. Adjust CT601 to make sure that the frequency is 903.052467 MHz.

Press the “2” key to enter the TEST Mode 2. Connect the AF Generator to the MIC Connector. Make sure that the output is 1kHz 9mV from the AF Generator. Connect the Deviation Meter to the RF test point on the handset MAIN PCB. Adjust RT602 to indicate ±8 kHz Dev.

Alignment Point Location on Handset Main PCB

HAND Main PCB

RT602

J601

MC601

— 6 —

RF Test Point

RT601

CT601

Receiver Section

Connections

RF SG

DC Power Supply

Test PointSPTerminal

J601

Battery

Connector

DC 3.8V

Dummy Load

WHT BLK

AF Test Point

(150-ohm)

DC Voltmeter

AC VoltmeterHANDSET Unit

Preset

a) Connect DC power supply to battery connector on the handset unit. b) Turn the DC power supply ON while pressing “ ∗ ” and “ # ” keys, and keep pressing the keys continuously for

approximate 2 seconds.

c) Release keys when entering TEST mode 1 with TALK LED lighting and beep.

Alignment Procedure

step

Preset to

SG: 1mV

No modulation

SG: 1mV

1 kHz ±8kHz

deviation

SG: -6.0 dBµV

1kHz ±8kHz

Deviation

Adjustment

L615

(Discriminator

Voltage)

RT604

(RX AF

Voltage)

RT603

(SQ Point)

Remarks

Press the 4 key to enter the TEST Mode 4. Connect the RF Singal Generator to the RF test point on the handset MAIN PCB. Make sure that the frequency is 926.997467 MHz. Connect the DC Voltmeter to the AF Terminal of RT603. Adjust L615 to indicate DC 0.85 V.

Connect the RF Signal Generator to the RF test point on the handset MAIN PCB. Make sure that the frequency is 926.997467 MHz. Connect the AC Voltmeter across a 150-ohm dummy to the SP Terminal. Adjust RT604 for a -19.0 dBV reading on the AC Voltmeter.

Press the 5 key to enter the TEST Mode 5. Make sure that the frequency of RF SG output is 926.997467 MHz. Adjust RT603 to turn to the point where the indication is just vibrated.

Alignment Point Location on Handset Main PCB

HAND Main PCB

J601

RT604

— 7 —

RT603

RF Test PointAF Test Point

L615

Base Unit

BLOCK DIAGRAMS

— 8 —

Handset Unit

— 9 —

RF Section

Base Unit

SCHEMATIC DIAGRAMS

— 10 — — 11 —

Base Key Unit

— 12 — — 13 —

Handset Unit

RF Section

— 14 — — 15 —

TROUBLESHOOTING HINTS

1. The bell of base unit does not ring.

Check RINGER mode setting is Hi or Low.

When the PAGE SW of the base is pressed, does the ringer on the handset ring?

When the TEL SG is joined with the base to make bell signal, is there pulse wave at Pin 4 of IC3?

Is there pulse wave at Pin 79 of IC6?

Check IC6 and its peripheral circuit.

Set RINGER volume setting to Hi or Low.

See 2. The bell does not ring & page does not ring.

Check IC3 and TEL network circuit.

Check R76, R232 and R234.

If you want to reset the unit to the factroy settings

You can cancel the OGM, PIN, and the clock settings by the following process. 1 Disconnect the AC adaptor and telephone line cord from the base. Keep the AC adaptor connected to the wall

outlet. Make sure that the telephone line cord remains disconnected during this procedure.

While pressing the DELETE button, plug the AC power adaptor into the base. Keep pressing the DELETE button for more than 5 seconds.

A beep sounds and “ P” blinks in the LED display.

To resume using the unit, connect the telephone line cord and place the handset on the base.

Note: If you turn on the unit again, “ P” may flash.

— 16 —

2. The bell of handset does not ring & page does not ring.

Can the base and handset be connected?

Press handset DIAL key while in TALK MODE. Can key touch sound be heard from the ringer?

Check IC6 and its peripheral circuit.

See 3. The base and handset cannot be connected.

When the key of the handset is pressed, can the pulse output at Pin 38 of IC608 be seen?

At the Q612 collector, can the pulse wave be seen?

Check RINGER Y601.

Check IC608.

Check R715, R726, R727, R728, R730, Q612, Q613 and D613.

— 17 —

3. The base and handset cannot be connected.

Check whether the base is able to set in the test mode 8.

NGACheck IC6 and its

peripheral circuit.

Check base RF section.

Check the TX POWER and the TX FREQUENCY on the base unit.

Check base RF section.

NG Check whether there is a

250 Hz data waveform at RT2.

Check RT2, R91, R98, R123, C92 and C147.

Check base RF section.

NG Check whether there is a

250 Hz data waveform at RT4 AF test point.

Check IC4 and its peripheral circuit.

Check whether there is a 250 Hz data waveform at Pin 10 of IC2.

Check RT4, IC2 and their peripheral circuits.

Check whether there is a 250 Hz data waveform at Pin 64 of IC6.

Check IC6 and its peripheral circuit.

Check whether the handset is able to be set in the test mode 1.

Check IC608 and its peripheral circuit.

Check the TX POWER and the TX FREQUENCY on the handset unit.

NG Check handset RF

section.

Check R79, R214, R215, IC2 and their peripheral circuits.

Set the base in the test mode 10, check whether deviation of the TX data is app. 9.0 kHz Dev.

Set the base in the test mode 13,

902.952467MHz (250 Hz ±8 kHz Dev.) 1mV output signal from RF test point is applied. Does the CHARGE LED light?

— 18 —

Set the handset in the test mode 3, check whether deviation of the TX data is app. 9.0 kHz Dev.

NG Check whether there is a

250 Hz data waveform at RT602.

Check R668, R712, R713, R716, R717, C719, C748 and RT602.

Set the handset in the test mode 6, 926.997467 MHz (250 Hz ±8 kHz Dev.) 1mV output signal from RF test point is applied. Check whether the bell ring.

Check whether the 250 Hz data waveform from Pin 9 of IC603 is fed.

Check IC603 and its peripheral circuit.

Check whether there is a 250 Hz data waveform at Pin 10 of IC602.

Check IC602 and its peripheral circuit.

Check whether there is a 250 Hz data waveform at Pin 40 of IC608.

Check R648, R649, IC602 and their peripheral circuits.

Check IC608 and its peripheral circuit.

Place the handset on the base to charge about 5 seconds, then connect again.

Check handset RF section.

— 19 —

4. Cannot make a phone call (pulse).

Can the base and handset be connected?

While in TALK MODE, press dial key of the handset. Check whether square waveform from Pin 80 of IC6 is fed.

Check Q12, RL1 and their peripheral circuits.

5. Cannot make a phone call (tone).

See 3. The base and handset cannot be connected.

Check IC6.

Can the base and handset be connected?

While in TALK MODE, press dial key of the handset. Can tone waveform from Pin 36 of IC6 is fed?

Can tone signal be heard from the handset speaker?

Check the base TEL-line circuit and RELAY control circuit.

See 3. The base and handset cannot be connected.

Check IC6.

Check IC2, Q3 and their peripheral circuits.

— 20 —

+ 41 hidden pages

Toshiba FT 8901A Service Manual

CONTENTS

SAFETY PRECAUTIONS

OPERATING CONTROLS

ANSWERING MACHINE

ALIGNMENT PROCEDURE

BLOCK DIAGRAMS

SCHEMATIC DIAGRAMS

TROUBLESHOOTING HINTS