TOSHIBA FT8981 Service Manual
FILE NO. 2B0-200104
SERVICE MANUAL
CORDLESS TELEPHONE
FT-8981
PUBLISHED IN JAPAN, May, 2001
CONTENTS
SAFETY PRECAUTIONS ...................................................................................................................... 1
OPERATING CONTROLS ..................................................................................................................... 2
ANSWERING MACHINE ....................................................................................................................... 3
ALIGNMENT PROCEDURE .................................................................................................................. 4
BLOCK DIAGRAMS ............................................................................................................................... 8
SCHEMATIC DIAGRAMS .................................................................................................................... 10
TROUBLESHOOTING HINTS ............................................................................................................. 14
IC AND TRANSISTOR VOLTAGE CHART ......................................................................................... 21
SEMICONDUCTOR LEAD IDENTIFICATION ..................................................................................... 26
ELECTRICAL PARTS LOCATION ...................................................................................................... 28
WIRING DIAGRAMS............................................................................................................................ 30
EXPLODED VIEW AND MECHANICAL PARTS LIST ........................................................................ 32
PARTS LIST......................................................................................................................................... 34
ASSEMBLY PARTS LIST .................................................................................................................... 48
SPECIFICATIONS ............................................................................................................................... 49
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
LCD
Dot matrix display
LCD Display
VOL/RING Button
REDIAL Button
TALK Button
L.D. Button
(TONE) Button
MEM (Memory) Button
PAUSE Button
COMPANDOR NOISE REDUCTION
REDIAL FLASH
VOL/
RING
SELECT
T
ALK
PAUSE
ABC
TUV
OPER
DEF
2
MNO
JKL
5
8
0
FUNC
1
GHI
4
PQ
RS
7
TONE
MEM
CID
LOCALL.D.
WX
YZ
DELETE
3
6
9
#
CH
FLASH Button
SELECT Button
CID Button
LOCAL Button
Dialpad
#
(PULSE) Button
DELETE CH Button
FUNC Button
Charging contact
BASE UNIT CONTROLS AND FUNCTIONS
DC IN 9V Jack
TEL LINE MODULAR Jack
Number of calls
Date Time
Caller’s telephone number
Caller’s name
Rechargeable
Battery Pack (back)
SETTING THE DIAL MODE
1 Press and hold
hear a confirmation tone.
2 To set the dial mode for pulse
dialing, press
mode for tone dialing press
confirmation tone sounds to
indicate the setting is complete.
FLASH
until you
#
. Or to set the dial
. A
POWER LED
IN USE LED
CHARGE LED
MENU Button
SET Button
REW REPEAT/SELECT
Button
GREETING Button
Charging Contact
COMPANDOR NOISE REDUCTION
DIGITAL CALLER ID / ANSWERING SYSTEM
CORDLESS TELEPHONE
POWER
IN USE
CHARGE
MENU
SET
SELECT SELECT
D
E
L
GREETING
MIC
REC
PAG E
MEMO/2WAY
W
S
E
R
N
A
S
K
I
P
P
O
T
E
T
E
S
/
Y
A
L
P
— 2 —
VOLUME
TIME
Antenna
PAGE Button
REC MEMO/2WAY Button
ANSWER Button
VOLUME Button
VOLUME Button
SKIP FF/SELECT Button
PLAY/STOP Button
TIME Button
DELETE Button
SETTING THE CLOCK
1. Press
MENU
twice, then press
ANSWERING MACHINE
SET
.
2. Select the day of the week by pressing
SET
SET
.
SELECT
SELECT
.
SELECT
press
3. Select the hour by pressing
SET
.
4. Select the minute by pressing
press
5. Select AM/PM by pressing
SELECT
or
or
SELECT
or
SELECT
SELECT
or
. 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
MENU
once, then press
2. Start to record your message after the guidance.
3. Press
REC MEMO/2WAY
or
To change the greeting message:
1. Press
2. Press
GREETING
SELECT
.
or
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
MENU
three times.
SET
to change the security code (PIN).
SELECT
SET
to set the security code (PIN).
or
SELECT
until the desired number appears.
— 3 —
ALIGNMENT PROCEDURE
Base Unit
Transmitter Section
Connections
RF
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
J1
1kHz -15dBm
AF GEN.
AC
Adapter
AC 120V
60Hz
step
1
2
Adjustment
RT301
(TX Power)
CT1
(TX Frequency)
Remarks
Connect the Power Meter to the RF test point on the Base MAIN PCB.
Adjust RT301 for a -6.0dBm 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
3
RT3
(TX Modulation)
Generator to the TEL Line Jack on the Base Main PCB. Make sure that
the output is 1 kHz -15dBm from the AF Generator.
Connect the Deviation Meter to the RF test point on the Base MAIN PCB.
Adjust RT3 to indicate ±8 kHz Dev.
Alignment Point Location on Base Main PCB and Base RF PCB
Base Main PCB
J1
J2
TEL LINE Jack
DC IN 9V Jack
CT1
— 4 —
RT3
Base RF PCB
RT301
RF Test Point
Receiver Section
Connections
RF SG
-
+
RF
Test Point
TEL Line
Jack
J1
Dummy Load
(600-ohm)
-
+
AC VoltmeterBASE Unit
AC 120V
60Hz
AC
Adapter
DC IN 9V Jack
J2
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
1
SG: 1mV
No modulation
SG: 1mV
2
1 kHz – 8kHz
deviation
SG: −6.0dBµV
3
No modulation
Adjustment
L4
(Discriminator
Voltage)
RT2
(RX AF
Voltage)
RT1
(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 L4 to indicate DC
1.00 V.
Connect the AC Voltmeter across a 600-ohm dummy to the Telephone Line
Jack. Adjust RT2 for a -12dBm reading on the AC voltmeter.
Press thePress the SKIP / FF key to enter the TEST Mode 12.
Make sure that the frequency of RF SG output is 902.952467 MHz.
Adjust RT1 to turn to the point where the LED indication is just vibrated.
Alignment Point Location on Base Main PCB and Base RF PCB
Base Main PCB
RT1
RT2
L4
RF Test PointAF Test Point
J1
J2
TEL LINE Jack
DC IN 9V Jack
— 5 —
Handset Unit
Transmitter Section
Connections
Power
Meter
Frequency
Counter
Deviation
Meter
RF
Test Point
RF
Test Point
HANDSET Unit
J603
Battery
Connector
MIC+Pin
DC 3.8V
AF GEN.
1kHz 9mV
DC Power Supply
Preset
a) Connect the handset RF unit to the handset main unit.
b) Connect DC power supply to battery connector on the handset unit.
c) Turn the DC power supply on while pressing “ ∗ ” and “ # ” keys, and keep pressing the keys continuously for
approximate 2 seconds.
d) Release keys when entering TEST mode 1 with beep.
Alignment Procedure
Step
1
2
3
Adjustment
RT501
(TX Power)
CT601
(TX Frequency)
RT603
(TX Modulation)
Remarks
Connect the RF power Meter to the RF test point on the handset MAIN PCB.
Adjust RT501 for a -5dBm 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 RT603 to indicate ±8 kHz Dev.
Alignment Point Location on Handset Main PCB and Handset RF PCB
Handset PCB
RT603
J603
CT601
MC601
— 6 —
RF PCB
RF Test Point
RT501
Receiver Section
Connections
RF SG
DC Power Supply
-
+
Battery
Connector
DC 3.8V
RF
Test Point
J603
SP
Connector
AF
Terminal
Dummy Load
(150-ohm)
-
+
DC Voltmeter
AC VoltmeterHANDSET Unit
Preset
a) Connect the handset RF unit to the handset main unit.
b) Connect DC power supply to battery connector on the handset unit.
c) Turn the DC power supply on while pressing “ ∗ ” and “ # ” keys, and keep pressing the keys continuously for
approximate 2 seconds.
d) Release keys when entering TEST mode 1 with beep.
Alignment Procedure
Step
Preset to
1
SG: 1mV
No modulation
SG: 1mV
1 kHz ±8kHz
2
Deviation
SG: -6.0 dBµV
1kHz ±8kHz
3
Deviation
Adjustment
L603
(Discriminator
Voltage)
RT602
(RX AF
Voltage)
RT601
(SQ Point)
Remarks
Press the 4 key to enter the TEST Mode 4. 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 DC Voltmeter to the Discriminator test point. Adjust L603 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 MIC Connector.
Adjust RT602 for a 80 mV 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 RT601 to turn to the point
where the Ringer just beeps.
Alignment Point Location on Handset Main PCB and Handset RF PCB
Handset PCB
J603
Discriminator Test Point
RT601
RT602
— 7 —
L603
RF PCB
RF Test Point
Base Unit
BLOCK DIAGRAMS
— 8 —
Handset
— 9 —
Base Unit
SCHEMATIC DIAGRAMS
— 10 — — 11 —
Handset
— 12 — — 13 —
TROUBLESHOOTING HINTS
1. The bell does not ring.
Check RINGER mode setting
is Hi or Low.
OK
When the PAGE SW of the
base is pressed, does the
ringer on the handset ring?
OK
When the TEL SG is joined
with the base to make bell
signal, is there pulse wave at
pin 4 of IC2?
OK
Is there pulse wave at
pin 79 of IC4?
OK
Check IC4 and its
peripheral circuit.
NG
NG
NG
NG
Set RINGER volume setting
to Hi or Low.
See 2. The bell does not ring
& page does not ring.
Check IC2 and TEL network
circuit.
Check R82, R182 and R94.
If you want to reset the unit to the factory 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.
2 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.
Deletion of the Caller ID memory
To delete the Caller ID memory in the RAM, proceed with the following process:
1) Connect the battery with pressing and # buttons, and keep pressing the buttons continuously for
approximate 2 seconds.
2) Release buttons when entering TEST mode with beep.
3) Press
4) A confirmation beep will sound, then the data for caller ID is deleted.
(Note: Do not disconnect the battery until you hear the confirmation beep, otherwise the data may not be
completely deleted.)
CID
button.
— 14 —
2. The bell does not ring & page does not ring.
Can the base and handset be
connected?
OK
Press handset DIAL key
while in TALK MODE.
Can key touch sound be
heard from the ringer?
OK
When the PAGE SW of the
base is pressed, does pin67
of IC4 change from high to
low?
NG
NG
NG
See 3. The base and handset
cannot be connected.
When the key of the handset is
pressed, can the pulse output
at pin 58 of IC603 be seen?
OK
At the Q616 collector, can the
pulse wave be seen?
OK
Check RINGER Y601.
Check DSP unit.
NG
NG
Check IC603.
Check R688, R673, Q616,
R689, R672, Q617, R629
and D604.
Check IC4 and its peripheral
circuit.
OK
— 15 —
3. The base and handset cannot be connected.
Check whether the base
is able to set in the test
mode 8.
OK
NGACheck IC4 and its
peripheral circuit.
Check base RF unit.
NG
Check the TX POWER
and the TX FREQUENCY
on the base unit.
OK
OK
NG
Check base RF unit.
NG Check whether there is a
250 Hz data waveform at
MOD of RF unit.
Check RT3, R76, R91,
R49, C129, C122,
C33 and C52.
NG
OK
Check base RF unit.
OK
NG Check whether there is a
250 Hz data waveform at
RT2 AF test point.
Check IC3, Q1 and their
peripheral circuit.
NG
OK
Check whether there is a
250 Hz data waveform at
the Q2 collector.
Check RT2, Q2 and their
peripheral circuit.
NG
OK
Check whether there is a
250 Hz data waveform at
pin 64 of IC4.
NG
OK
Check IC4 and its
peripheral circuit.
Check whether the
handset is able to set in
the test mode 1.
OK
NG
Check IC603 and its
peripheral circuit.
Check the TX POWER
and the TX FREQUENCY
on the handset unit.
OK
NG
Check handset RF unit.
OK
Check R27, R171, R172,
IC1 and their peripheral
circuit.
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?
— 16 —
A
Check handset RF unit.
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
"MOD" of RF unit.
Check R635, R636, R634,
R632, R619, C610, C611,
C669 and RT603.
NG
OK
Check handset RF unit.
NG
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.
NG
Check whether the 250
Hz data waveform from
pin 9 of IC606 is fed.
Check IC606, Q612 and
their peripheral circuit.
NG
OK
OK
Check whether there is a
250 Hz data waveform at
the Q601 collector.
Check RT602, Q601 and
their peripheral circuit.
NG
OK
Check whether there is a
250 Hz data waveform at
pin 55 of IC603.
Check R618, R621,
IC601 and their
peripheral circuit.
NG
OK
Check IC603 and its
peripheral circuit.
OK
Place the handset on the
base to charge about 5
seconds, then connect
again.
OK
— 17 —
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