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SERVICE MANUAL
PUBLISHED IN JAPAN, July, 2001
FILE NO. 2B0-200110
SG-1991
CORDLESS TELEPHONE


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-- 1 --
CONTENTS
SAFETY PRECAUTIONS ...................................................................................................................... 1
OPERATING CONTROLS ..................................................................................................................... 2
ALIGNMENT PROCEDURE .................................................................................................................. 3
BLOCK DIAGRAMS ............................................................................................................................... 5
SCHEMATIC DIAGRAMS ...................................................................................................................... 8
TROUBLESHOOTING HINTS ............................................................................................................. 16
IC AND TRANSISTOR VOLTAGE CHART ......................................................................................... 27
SEMICONDUCTOR LEAD IDENTIFICATION ..................................................................................... 35
ELECTRICAL PARTS LOCATION ...................................................................................................... 39
WIRING DIAGRAMS ............................................................................................................................ 43
EXPLODED VIEW AND MECHANICAL PARTS LIST ........................................................................ 45
PARTS LIST ......................................................................................................................................... 48
ASSEMBLY PARTS LIST .................................................................................................................... 67
SPECIFICATIONS ............................................................................................................................... 68
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
in the schematic diagram and the parts list. Before replacing
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.


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-- 2 --
OPERATING CONTROLS
BASE UNIT CONTROLS AND FUNCTION
MEM
VOL
CID
FLASH
TA
L
K
ABC
2
JKL
5
TUV
8
OPER
0
DEF
3
MNO
6
WX
YZ
PQ
RS
9
#
GHI
4
7
1
RDL/P FUNCTION SELECT
CHANNEL
DELETE
INTCOM
TALK Button
MEM (Memory) Button
RDL/P Button
Charging contacts
DELETE
INTCOM
Button
SELECT
CHANNEL Button
FLASH Button
Dialpad
Rechargeable
Battery Pack(back)
Antenna
Headset jack
FUNCTION Button
VOL (Volume/Ringer) Button
2.4GHz DIGITAL
SPREAD
SPECTR UM
LCD
Number of calls
Dot matrix display
Date
Time
Caller's telephone number
Caller's name
L.D.
LOCAL
TONE
L.D. Button
(TONE
) Button
CID Button
LOCAL Button
(
) Button
#
2.4GHz DIGITAL
SPREAD
SPECTRUM
DIGITAL CALLER ID / ANSWERING SYSTEM
CORDRESS TELEPHONE
IN USE
CHARGE
SPEAKER
MUTE
REPEAT
SKIP
VOLUME
TIME
PIN
DELETE
PLAY / STOP
GREETING
MEMO
/ 2 WAY REC
MIC
ANSWER
MEMORY
REDIAL
/ PAUSE
FLASH
TONE
MUTE
INTCOM
SPEAKER
1
23
4
56
78
9
0
ABC
DEF
GHI
JKL
MNO
PQ
RS
TUV
WX
YZ
OPER
VOLUME Buttons
Antenna
LED display
DC in 9V jack
TEL LINE jack
IN USE/CHARGE LED
PLAY/STOP Button
ANSWER
Button
RING TIME switch
REC TIME switch
MEMORY Button
SPEAKER
Button
INTCOM
Button
MUTE
Button
Microphone
FLASH
Button
SKIP /
Button
TIME
Button
DELETE
Button
GREETING Button
REPEAT /
Button
PIN
Button
MEMO/2 WAY REC
Button
REDIAL/PAUSE Button
Speaker
Ringer ON/OFF switch
TONE/PULSE switch
SPEAKER/MUTE LED
HANDSET CONTROLS AND FUNCTIONS


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ALIGNMENT AND ADJUSTMENT
BASE UNIT
Transmitter Section
Connections
Spectrum Analyzer
Frequency Counter
Alignment Point Location on Base Main PCB and Base RF PCB
AC Adapter
(120V 60Hz)
Base Unit
Test Point
(J301)
Test Point
(REF)
Frequency Counter
Spectrum Analyzer
RF PCB
Test point (MOD)
Antenna Wire
Test point (REF)
Before alignment, remove solder and
take off hot side of antenna
wire from PCB.
Test point (J301)
CT1
S4
S3
J2
J1
S2
S1
RF UNIT
Alignment Procedure
Step
Adjustment
Remarks
1
CT1
(Frequency Adjust)
Connect the Frequency Counter to test point (REF).
Adjust CT1 so that the frequency is 6.144 MHz.
2
--
Connect the Spectrum Analyzer to test point (J301).
Confirm that the power instructions of the Spectrum Analyzer reaches more
than 8 dBm. After alingnment, be sure to re-solder the hot side of Antenna
wire on RF PCB.
Preset
a) Before alignment, be sure to remove solder and take off hot side of antenna wire from RF PCB (refer to the
illus. below).
b) Turn on AC power while the "INTCOM" key is being depressed. (Hold about 1sec.)


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-- 4 --
Alignment Point Location on Handset Main PCB and Handset RF PCB
Handset Unit
Test
Point
(J801)
Spectrum Analyzer
Test Poin
RF PCB
t
(REF)
Frequency Counter
Remove solder before alignment
Test point (REF)
Test point
(J801)
Test point (MOD)
IC601
CT601
X601
IC604
RF UNIT
Alignment Procedure
Step
Adjustment
Remarks
1
CT601
(Frequency Adjust)
Connect the Frequency Counter to test point (REF).
Adjust CT601 so that the frequency is 6.144 MHz.
2
--
Connect the Spectrum Analyzer to test point (J801).
Confirm that the power instructions of the Spectrum analyzer reaches more
than 8 dBm. After alignment, be sure to re-solder the pattern of Main PCB.
HANDSET UNIT
Transmitter Section
Connections
Spectrum Analyzer
Frequency Counter
Preset
a) Before alignment, be sure to remove solder on the pattern of Main PCB (refer to the illus. below).
b) Turn the power ON (Connect battery) while depressing " " and "#" keys.
c) Press "1" key.