Casio fx-7400G Troubleshooting guide

R
fx-7400G(ZX-930A)
MAR. 1996
(without price)
fx-7400G
INDEX

CONTENTS
1. SCHEMATIC DIAGRAMS ..................................................................................1
2. SPECIFICATIONS............................................................................................. 3
3. REPLACING BATTERIES..................................................................................4
4. RESET OPERATION..........................................................................................6
5. ERROR MESSAGE ............................................................................................8
6. OPERATION CHECK .......................................................................................10
7. EXPLODED VIEW ............................................................................................12
8. PARTS LIST .....................................................................................................13

— 1 —
1. SCHEMATIC DIAGRAMS

— 2 —

— 3 —
2. SPECIFICATIONS
Display system: 13-character ×6-line display; 10-digit mantissa and 9-digit mantissa and 2-
digit exponent when using exponential format for calculations; displays
sexagesimal, fraction values
Power supply: Main: Two AAA-size batteries (LR03 (AM4) or R03 (UM-4))
Back-up: One CR2032 lithium battery
Power consumption: 0.05 W
Battery life*: LR03 (AM4): Approximately2,000hours(continuousdisplayofmainmenu)
Approximately 2 years (power off)
R03 (UM-4): Approximately1,000hours(continuousdisplayofmainmenu)
Approximately 2 years (poweroff)
Back-up: Approximately 2 years
* The batteries that have been installed in this unit when user purchased
it had been used in the factory test, so it will be impossible to fully satisfy
this specifications when these batteries are used.
Auto power off: Power is automatically turned off approximately six minutes after last
operation.
Ambient temperature range: 0°C ~ 40°C (32°F ~ 104°F)
Dimensions: 18.9 mm (H) ×77 mm (W) ×158 mm (D) (3/4" (H) ×3" (W) ×61/4" (D))
Weight: 130 g (4.6 oz) including batteries
Accessories: Hard case
Current Consumption:
TYP [µA] MAX [µA]
ON (MENU) 317.4 425.7
OFF 15.4

— 4 —
3. REPLACING BATTERIES
• To replace the main power supply batteries
1Press
SHIFT OFF
to turn the calculator off.
2Push the battery compartment cover on the back of the calculator
in the direction noted in the illustration and remove it.
3Remove the two old batteries.
4Load a new set of two batteries, making sure that their positive+
and negative -ends are facing in the proper directions.
5Replace the battery compartment cover and press
AC/ON
to turn
power on. The memory back-up battery provides power to the
memory while the main batteries are removed, so memory data
is not lost .
• Power will not switch on if you press
AC/ON
while the main power
supply battery compartment cover is open.
• Do not leave the unit without main power supply batteries loaded
for long periods. Doing so can cause deletion of data stored in
memory.
• If the figures on the display appear too light and hard to see after
you turn on power, adjust the contrast using the following
procedure.
1. Press
MENU
.
2. Use the cursor keys ( , , , ) to select the CONT icon and press
EXE
or simply
press 7to display the contrast adjustment screen.
3. Press to make the figure on the screen lighter or to make them darker.
4. After getting the contrast the way you want it, press
MENU
to return to the main menu.
REMARK
* Never remove the main power supply and the memory back up batteries from the unit at the same time.
* Be sure to switch the unit off before replacing batteries. Replacing batteries with power on will cause
data in memory to be deleted.
* Never replace the main power supply battery compartment cover or turn the calculator on while the
main power supply batteries are removed from the calculator or not loaded correctly. Doing so can
cause memory data to be deleted and malfunction of the calculator. If mishandling of batteries causes
such problems, correctly load batteries and then perform the RESET operation to resume normal
operation.
* Be sure to replace all two batteries with new ones.

— 5 —
• To replace the memory back up battery
1Press
SHIFT OFF
to turn the calculator off.
2Push the battery compartment cover on the
back of the calculator in the direction noted in
the illustration and remove it.
3Remove screw Don the back of the calculator,
and remove the back up battery holder.
4Remove the old battery.
5Wipe off the surfaces of a new battery with a
soft, dry cloth. Load it into the calculator so that
its positive +side is facing up.
6Pressing down on the battery with the battery
holder, replace the screw that secures the
holder in place.
7Replace the battery compartment cover and
press
AC/ON
to turn power on. The main battery
provides power to the memory while the back-
up batteries are removed, so memory data is
not lost.
REMARK
* Before replacing the memory back up battery, turn on the unit and check to see if the "Low battery!"
message appears on the display. If it does, replace the main power supply batteries before replacing
the back up power supply battery.
* Neverremove themain powersupply and thememory backup batteriesfrom theunit at thesame time.
* Be sure to switch the unit off before replacing batteries. Replacing batteries with power on will cause
data in memory to be deleted.
* Be sure to replace the back up power supply battery at least once 2 years, regardless of how much
you use the unit during that time. Failure to do so can cause data in memory to be deleted.
Important
Data stored in memory can be corrupted or lost if battery power drops below a certain level. When this
happens, you must perform the RESET operation to restore normal operarion. Note that the RESET
operation clears all data from memory. Because of this, you should be sure to keep written copies of
all important data to avoid losing it due to low battery power.
D

— 6 —
Memory
Memory Usage
Reset
Select
Set :
:[ ] [ ] [ EXE ]
✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽
✽ ✽
✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽
R E S E T
R E S E T
A L L M E M O R I E S ?
Y E S NO
RESET ALL
4.RESET OPERATION
Warning!
The procedure described here clears all memory contents. Never perform this operation unless you
want to totally clear the memory of the calculator. If you need the data currently stored in memory, be
sure to write it down somewhere before performing the RESET operation.
•To reset the calculator
1Press
MENU
to display the Main menu.
2Highlight the MEM icon and press
EXE
, or press 8.
3Use to move the highlighting down to "Reset" and then press
EXE
.
4Press F1 (YES) to reset the calculator or F4 (NO) to abort the operation without resetting
anything.
F4F1
✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽
✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽ ✽
R E S E T
A L L M E M O R I E S !

— 7 —
Resetting the calculator initializes it to the following settings.
Initial Setting
RUN
Rad
Norm 1
Automatic
Display
Rectangular coordinate (Y=)
Automatic
Clear
Clear
Clear
Clear (initialized)
Clear
Clear
Clear (initialized)
Clear
Clear
Clear
Clear
Clear
Item
Icon
Angle Unit
Exponent Display Range
Fraction Reduction
Mixed Fraction
Graph Type
Statistical Graph
Variable Memory
Answer Memory (Ans)
Graphic Display/Text Display
View Window
View Window Memory
Graph Function
Enlargement/Reduction Factor
Table & Graph Data
List Data
Statistical Calculation/Graph Memory
Program
Input Buffer/AC Replay
• Performing the RESET operation while an internal calculation is being performed (indicated by a blank
display) will cause all data in memory to be deleted. Make sure that no calculation be being performed
before starting a RESET operation.
• If the calculator stops operating correctly for some
reason, use a thin, pointed object to press the
RESET button on the back of the calculator. This
should make the RESET confirmation screen
appear on the display. Perform the procedure to
complete the RESET operation.
RESET button

— 8 —
5. ERROR MESSAGE
Meaning
1Calculation formula contains an error.
2Formula in a program contains an
error.
1Calculation result exceeds calcula-
tion range.
2Calculation is outside the input range
of a function.
3Illogical operation (division by zero,
etc.)
4Poor precision in differential calcula-
tion results.
1No corresponding Lbl nfor Goto n.
2No program stored in program area
Prog “file name”.
3No corresponding “Next” for “For”, no
corresponding “LpWhile” for “Do”, or
no corresponding “whileEnd” for
“While”.
• Nesting of subroutines exceeds 10
levels.
• Execution of calculations that exceed
the capacity of the stack for numeric
values or stack for commands.
Message
Syn ERROR
Ma ERROR
Go ERROR
Ne ERROR
Stk ERROR
Countermeasure
1Use or to display the point
where the error was generated and
correct it.
2Use or to display the point
where the error was generated and
then correct the program.
123
Check the input numeric value and
correct it.
When using memories, check that the
numeric values stored in memories
are correct.
4Try using a smaller value for ∆x
(xincrement/decrement).
1Correctly input a Lbl ntocorrespond to
the Goto n, or delete the Goto nif not
required.
2Store a program in program area Prog
“file name”, or delete the Prog “file
name” if not required.
3Correctly match “Next” with “For”,
“LpWhile” with “Do”, or “whileEnd”
with “While”.
• Ensure that Prog “file name” is not
used to return from subroutines to
main routine. If used, delete any un-
necessary Prog “file name”.
• Trace the subroutine jump destina-
tions and ensure that no jumps are
made back to the original program
area. Ensure that returns are made
correctly.
• Simplify the formulas to keep stacks
within 10 levels for the numeric values
and 26 levels for the commands.
• Divide the formula into two or more
parts.