Casio SF7900 Service Manual
SF-7900(LX-522)
OCT. 1994
(with price)
SF-7900
R
CONTENTS
SPECIFICATIONS ................................................................................................................ 1
TO REPLACE THE BATTERY ............................................................................................. 2
TO CHECK THE MEMORY CAPACITY ............................................................................... 2
ERROR MESSAGE............................................................................................................... 3
TO RESET THE SF UNIT'S MEMORY ................................................................................. 4
TO SAVE THE DATA TO ANOTHER UNIT ......................................................................... 5
BLOCK DIAGRAM................................................................................................................ 8
CIRCUIT EXPLANATIONS
System chart................................................................................................................. 9
Power supply circuit .................................................................................................. 10
CPU pin description (HD62076C03).......................................................................... 12
Gate array pin descriptions (SSC2571F0A)............................................................. 13
Operation program ROM pin descriptions .............................................................. 14
RAM pin descriptions ................................................................................................ 14
DIAGNOSTIC OPERATION................................................................................................ 15
TROUBLESHOOTING ........................................................................................................ 20
SCHEMATIC DIAGRAM
Main PCB .................................................................................................................... 21
Display PCB................................................................................................................ 22
Key Matrix ................................................................................................................... 23
Key Matrix (Display side)........................................................................................... 24
PARTS LIST........................................................................................................................ 25
ASSEMBLY VIEW .............................................................................................................. 27
SPECIFICATIONS
Main modes: Telephone Directory, Business Card Library, Memo, Schedule Keeper,
Expense, Reminder, Calendar, Home Time, World Time and Calculator
Data storage: Storage and recall of telephone, business card, memo, schedule, expense,
reminder data, calendar display, secret area; editing; memory status display
Clock: World Time; reminder alarm; schedule alarm; daily alarm; accuracy under
normal temperatures: ±3 seconds average
Calculation: 12-digit arithmetic calculations; arithemetic constants (+, –, ×, ÷); independ-
ent memory; percentages; square roots; 24-digit approximations; date calculations; other mixed calculations
General:
Display element: 16-column × 8-line LCD
Memory capacity: 128kB (103436 bytes)
Main component: LSI
Power supply: 3 lithium batteries (CR2032)
Power consumption: 0.07 W
Battery life: Approximately 170 hours continuous operation in Telephone Directory;
approximately 130 hours repeating one minute of input and 10 minutes of
display in Telephone Directory; approximately 12 months for memory back
up
Auto power off: Approximately 6 minutes after last key operation
Operating temperature: 0°C ~ 40°C (32°F ~ 104°F)
Dimensions:
Unfolded: 9.55H × 144W × 155D mm (3/8"H × 5 11/16"W × 6 1/8"D)
Folded: 15.95H × 144W × 77.5D mm(5/8"H × 5 11/16"W × 3 1/16"D)
Weight: 124g (4.4 oz.)
• Design and specifications are subject to change without notice.
Current consumption:
Power switch TYP. [µA] MAX [µA]
OFF 11.7 37.1
ON 1,670.0 13,711.0
ON (Operating) 4,520.0 16,645.0
— 1 —
TO REPLACE THE BATTERY
To replace the batteries
1. Loosen the screw on the back of the SF unit that holds the battery compartment cover in
place, and remove the cover.
Caution
In the next step, be sure to remove only one battery at a time.
Otherwise, you will lose all data stored in memory.
Screw
2. Loosen the screw that secures one of the three battery holders
in place and remove the battery holder.
3. Replace the old battery with a new one, making sure that the
positive (+) side of the new battery is facing up (so you can see
it).
4. Replace the battery holder and secure it by tightening its screw.
RESET
+
TO CHECK THE MEMORY CAPACITY
Hold down CAPA to display a screen that shows the current memory status. To clear the memory
status display, release
Remaining memory
capacity
CAPA .
CAPACITY
FREE
USED
0 10050
76420Bytes
27016Bytes
26
%
Total number of characters stored in memory
— 2 —
ERROR MESSAGE
Message Meaning Action
DATA ITEM Search operation Current search operation
NOT FOUND! attempted when no data cannot be performed.
NO DATA is stored in memory.
IN MEMORY!
DATA ITEM Data specified in search Change specification or
NOT FOUND! operation does not exist cancel search.
MEMORY FULL! No more room in memory Delete unnecessary data
ALARM TIME Attempt to set a Schedule Set a different alarm time
ALREADY USED! Keeper alarm time that or change the existing alarm
ALARM TIME Attempt to set a Schedule Set a different alarm time
ALREADY PASSED! Keeper alarm time for a (for a future time/date.)
in memory.
for storage of data. items from memory.
is already used for time to another one.
another entry.
time/date that is already
passed.
SECRET DATA! Alarm for a secret Enter the secret memory
memory area data item is area to view details of the
sounding. alarm.
PASSWORD Attempt to enter the Use the correct password.
MISMATCH! secret memory area
using a password that
does not match the one
preset for the secret area.
TRANSMIT ERROR! Error during data Cancel the data
communications. communications
STOPPED! operation and try again.
DATA ERROR! Data corrupted by strong See page 11 of the
CONSULT THE impact, electrostatic owner's manual.
OWNER'S MANUAL! charge, etc.
SAME TYPE Attempt to store a label Use a different label.
ALREADY USED! that is identical to one
already stored.
— 3 —
TO RESET THE SF UNIT'S MEMORY
The following procedure erases all data stored in the memory of the SF unit.
Perform the following operation only when you want to delete all data and initialize the settings of the SF
unit.
Remember – you should always keep copies of important data by writing it down, by transferring it to a
personal computer or other SF unit.
To reset the SF Unit's memory
RESET button
RESET
1. Switch on power and press the RESET button with a thin, pointed object.
Warning!
The next step deletes all data stored in the SF unit's memory. Make sure that you really want
to delete the data before you continue!
2. Press Y to reset the memory and delete all data or N to abort the reset operation without
deleting anything.
Following the reset operation described above, the Home Time display appears and the SF unit
settings are initialized as noted below.
Home Time: 12-hour format
JAN/1/1995
AM/12:00 00
World Time: Washington D.C.
Daily Alarm: 12:00 PM
Sound: Schedule alarm → ON
Reminder alarm → ON
Daily alarm → OFF
Key → ON
Character input: CAPS
— 4 —
TO SAVE THE DATA TO ANOTHER UNIT
SF-7900 can transfer customers data to another SF-7900 with memory protection only when replacing
the LCD or the outer case.
How to transfer the data
* Before connecting the cable (SB-60 or SB-62), be sure to reset the slave unit to clear all
data.
1) Turn off the power switch and connect the two units using the cable (SB-60 or SB-62) as shown in
the drawing.
2) Turn on the power switch of both units.
3) The slave unit must be set the date of Feb. 3rd, 1901 into the memory under the calculator
mode.
Operation: 1 DATE 2 DATE 3 DATE M+
CLEAR
ON
CAL
If you don't set the date, the "PASSWORD" isn't transferred to the slave unit.
4) Check the hardware parameters, and if the units have another condition, reset as follows.
To change the hardware
parameters, press the
, , and
cursol keys.
PARITY NONE
BIT LENGTH 7
SET UP
To set the hardware
parameters, press the SET
BPS 9600
key.
TEL
FUNCTION FUNCTION 4 3
— 5 —
5) Set up the slave unit.
1 While in the Calendar Display, Telephone Directory, Business Card Library, Memo Mode, or
Schedule Keeper, press the FUNCTION key followed by 4 to select " DATA COMM", and
the following menu appears.
TEL
FUNCTION 4
1 SEND
2 RECEIVE
3 PRINT
4 SET UP
2 Press 2 to select "RECEIVE" and the following display appears to indicate that the slave unit
is ready to receive data.
2
DATA
RECEIVE OK
TO STOP
PRESS [ESC]
6) Set up the customer's unit.
1 While the transmitting unit is in the Calendar Display, Telephone Directory, Business Card
Library, Memo Mode, or Schedule Keeper, press the FUNCTION key followed by 4 to
select "DATA COMM", and the following menu appears.
TEL
FUNCTION 4
1 SEND
2 RECEIVE
3 PRINT
4 SET UP
2 Press 1 to select "SEND" and the following menu appears.
SEND
1
1 ONE ITEM
2 MODE DATA
3 ALL DATA
— 6 —
3 Press 3 to select "ALL DATA". The following display appears to confirm if you wish to
proceed.
SEND ALL
3
DATA ITEM ?
SET / ESC
4 Press the SET key to proceed with the data transmission, or press ESC if you wish to
cancel.
SET
NOW SENDING !
TO STOP, PRESS ESC
Data are transmitted in the sequence of Telephone Directory data, Memo data, Reminder data,
Schedule Keeper data and Calendar data.
* The following messages appear on the display of the receiving unit when a problem occurs during
data communications. All data transferred up to display of the message is retained in memory, but
data communication is terminated.
If one of the following error messages appear, press the , , , , ,
CAL
, keys, to clear the error message. Then, take corrective action and try data
CALENDAR
TEL
MEMO
HOME/WORLDSCHEDULE
REMINDER
communication again.
Message Meaning Action
TRANSMIT ERROR! Error during data Cancel the data
STOPPED! communications. communications operation
and try again.
DATA ERROR! Data corrupted by strong See page 9 of the owner's
CONSULT THE impact, electrostatic manual.
OWNER'S MANUAL! charge, etc.
— 7 —
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