background image
CORDLESS TELEPHONE
SERVICE MANUAL
PUBLISHED IN JAPAN, Jun., 1998
FT-7807R
FILE NO. 2B0-9803


background image
-- 1 --
CONTENTS
SAFETY PRECAUTIONS ...................................................................................................................... 1
OPERATING CONTROLS ................................................................................................................... 2
ALIGNMENT PROCEDURE ................................................................................................................. 3
BLOCK DIAGRAMS .............................................................................................................................. 7
SCHEMATIC DIAGRAMS ..................................................................................................................... 9
TROUBLESHOOTING HINTS ........................................................................................................... 13
IC AND TRANSISTOR VOLTAGE CHART ....................................................................................... 19
SEMICONDUCTOR LEAD IDENTIFICATION ................................................................................... 23
ELECTRICAL PARTS LOCATION ..................................................................................................... 27
WIRING DIAGRAM ............................................................................................................................. 29
EXPLODED VIEW AND MECHANICAL PARTS LIST ...................................................................... 30
PARTS LIST ........................................................................................................................................ 34
ASSEMBLY PARTS LIST ................................................................................................................... 48
SPECIFICATIONS .............................................................................................................................. 49
APPENDIX .......................................................................................................................................... 52
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.


background image
-- 2 --
OPERATING CONTROLS
HANDSET CONTROLS
BASE UNIT CONTROLS
LCD
(
) button (down arrow button)
Used to scroll down the display screen.
(
) button (up arrow button)
Used to scroll up the display screen.
"
%
#
&
!
$
'
ABC
JKL
TUV
GHI
PQ
RS
WX
Y Z
MNO
DEF
OPER
FLASH
CH
VOL/RING RDL
FUNC DELETE CANCELPAUSE
TALK
MEM
CID
0-9, , # Dial buttons
TONE
TONE button
RDL(Redial)/PAUSE button
Battery compartment
VOL/RING/CHANCEL button
CH (channel)/DELETE button
FLASH/FUNC (Function) button
Press to enter the Function Mode to
perform various settings. Each time
the
button is pressed, the
menu changes in the following order:
DIAL MEMORY
AREA CODE
CIDCW ON\OFF
AUTO TALK
ON\OFF.
CID (Caller ID) button
Press to enter the caller ID mode.
MEM button
TALK button
Liquid Crystal Display (LCD)
Helical antenna
Charging contacts
Number 1 button
Used for long distance dialing.
Number 8 (
) button (time button)
Used to display the date and time of the received calls.
Number 9 (
) button
Used to display the number of calls attempted by a caller
.
FUNC
talk
call id
mem
talk icon
Blinks
-while the handset is connecting
to the base unit.
-when a channel is being changed.
Displayed during a call in progress
on the handset.
Displayed during the caller ID
review mode.
call id icon
mem icon
Displayed
-while data is being stored in an
deleted from memory.
-while the Function Mode is in
use.
Dot matrix display
Twelve digits by two lines dot
matrix LCD. Shows the time, caller
ID, memory location, instructions,
error messages, and other
information.
The back light of the LCD operates
in the following manner:
Turns on during an incoming call
when the ringer is OFF.
Turns on for 5 seconds and then
off
-when a button is pressed (except
in battery low status).
-when the phone rings and the
handset is lifted from its cradle on
the base unit to answer a call.
Battery icon
Displayed while the handset is being
charged.
Displayed while the handset is being
charged during the battery low status.
Blinks when the battery low status
occurs during standby and phone
conversation.
ALL DIGITAL CALLER ID
CORDLESS TELEPHONE
25 CH SCANNING FT-7807
IN USE
CHARGE
POWER
PAGE
IN USE LED
CHARGE LED
POWER LED
PAGE button
Cradle
LINE modular jack
DC IN 9V jack
Tone/Pulse switch
Base antenna


background image
-- 3 --
ALIGNMENT PROCEDURE
BASE UNIT / TRANSMITTER
Test Equipment Required and Connections
· Oscilloscope
· Dummy Load, 50-ohm
· Frequency Counter
· AC Power Supply: 120V, 60Hz (With AC Adapter)
· Digital Voltmeter
Preset
a) Set T/P SW to Pulse Mode.
b) Turn on AC power while the Page key is being depressed.
c) Release the Page key about 2 seconds later, then the TX Mode is entered (CH21).
Alignment Procedure
Step
Adjustment
Remarks
1L10
Connect the oscilloscope across a 50-ohm load to RF test point.
Set the digital voltmeter at the test point of TX VCO.
Adjust L10 to indicate DC 2.8
±0.05 V (VCO).
2
Connect the frequency counter across a 50-ohm dummy load to RF test
point. Make sure that the frequency is 46.770 MHz
±1500 Hz.
Alignment Point Location on Main (Base Unit) PCB
-
+
AC Adapter
(120V 60Hz)
Base Unit
J2
DC IN 9V
JACK
RF Test
Point
Dummy Load
(50-ohm)
Frequency Counter
Oscilloscope
Digital Voltmeter
TX VCO
Test Point
TX VCO Test Point
DC IN 9V Jack
T/P SW
P
T
J2
S1
L10
RF Test Point
L1


background image
-- 4 --
RECEIVER
Test Equipment Required and Connections
· SG: RF Signal Generator, 49.830 MHz, 49.160 MHz
· Dummy Load, 600-ohm
· Digital Voltmeter
· AF SSVM
· SINAD Meter
Alignment Procedure
Step
Preset to
Adjustment
Remarks
1
SG: 1 mV
No modulation
L7
Connect the SG to the RF test point.
Connect the digital voltmeter to the test point of the RX VCO.
Adjust L7 to indicate DC 1.4
±0.05 V.
2
SG: 1 mV
1 kHz
±3kHz
deviation
L3
Connect the digital voltmeter to the test point of Discriminator.
Adjust L3 to indicate DC 2.0
±0.05V.
3
SG: 1 mV
1 kHz
±3 kHz
deviation
RT1
Adjust RT1 to make AF SSVM value
-5 dBm ±0.5 dB.
4
SG: 1 mV
1 kHz
±3 kHz
deviation
L6
Set T/P SW to TONE Mode. Press the Page key once, then CH
changes to CH 8.
Connect the AF SSVM to the TEL LINE across a 600-ohm dummy
load.
Keep the SINAD reading at 12 dB by adjusting the SG output. Adjust
L6 for maximum SINAD reading.
Preset
a) Set T/P SW to Pulse Mode.
b) Turn on AC power while the Page key is being depressed.
c) Release the Page key about 2 seconds later, then the TX Mode is entered (CH21).
d) Press the Page key 4 times, then the RX Mode is entered (CH21).
Alignment Point Location on Main (Base Unit) PCB
-
+
SG
Base Unit
AF SSVM
Digital Voltmeter
SINAD
Meter
MOD = 1KHz
DEV = ±3kHz
AC Adapter
(120V 60HZ)
Dummy Load
(600-ohm)
RX VCO
Test Point
RF Test
Point
TEL Jack
RT1
L3
L7 L6
RX VCO
Test Point
Discriminator
Test Point
DC IN 9V Jack
T/P SW
J2
S1
RF Test Point
L1
P
T