Q: Why does the OLIVETTI LOGOS 694ΑT calculator perform an automatic multiplication when entering an addition?

The OLIVETTI LOGOS 694ΑT calculator has a constant calculation function that allows for repeated multiplications or divisions with a stored value. If you notice that a multiplication occurs automatically when entering an addition, it is likely that a constant calculation mode has been accidentally activated or misinterpreted. Probable cause: The constant calculation mode is intended to multiply or divide a number by a fixed value stored in memory. If this mode is active, entering a number and then pressing an operation key other than the standard addition may trigger a multiplication. Also, ensure you are using the correct keys: for a simple addition, you should use the [+]1 or [+]2 key depending on the chosen totalizer, not a special function key. Procedure for using simple addition: Enter the first amount to add Press the [+]1 key (or [+]2 for the second totalizer) Enter the next amount Press [+]1 (or [+]2 ) again Continue for all your additions To obtain the result, press [T]1 or [T]2 (Total key) If the problem persists: It is possible that a key is faulty or physically stuck, or that a memory function is programmed on your machine. Press the [C/CE] key twice to completely reset the calculator (this clears all contents, including totalizers and Grand total memory). Then test a simple addition to check that normal operation is restored. If addition still triggers a multiplication, consult a specialized calculator repair technician, as this may indicate a hardware malfunction or modified internal programming.

Question 1

How to disable or reduce the backlight of the LCD display?

Accepted Answer

The technical manual of the OLIVETTI LOGOS 694ΑT calculator does not mention any control or setting to adjust or disable the backlight of the 14-character LCD screen.

This device, dating from the 1970s-1980s, does not have a built-in software function to manage the brightness of the display. This is a common feature of desktop calculators from that era.

Possible alternatives:

If the brightness bothers you, you can slightly decrease the distance between your eyes and the screen or adjust the viewing angle
Check that the calculator is not overheating - the manual specifies that optimal operation is between 0-40°C
If the display seems abnormally bright, a technical check with the manufacturer can determine if it is a malfunction

Question 2

The LCD display shows a lot of zeros but the numbers I enter do not display correctly - how can I fix this?

Accepted Answer

This problem is characteristic of old liquid crystal LCD screens that degrade over time. Your OLIVETTI LOGOS 694ΑT calculator has a 14-character LCD screen, and this symptom usually occurs after several years of use.

Possible causes:

Degraded liquid crystals - after years, the liquid crystals lose their effectiveness, causing erratic display of some pixels (hence the visible zeros but the other numbers being invisible).
Overheating - according to the manual, the operating temperature range is 0-40°C. Make sure you are not covering the calculator while it is in use (risk of overheating) and that the area is well-ventilated.
Excessive humidity or exposure to sunlight - the manual recommends avoiding areas with high humidity, dust, and direct sunlight exposure.

Solutions to try:

Let the calculator rest for a few hours at room temperature, then turn it back on. Sometimes, the liquid crystals

Question 3

Why does the OLIVETTI LOGOS 694ΑT calculator perform an automatic multiplication when entering an addition?

Accepted Answer

The OLIVETTI LOGOS 694ΑT calculator has a constant calculation function that allows for repeated multiplications or divisions with a stored value. If you notice that a multiplication occurs automatically when entering an addition, it is likely that a constant calculation mode has been accidentally activated or misinterpreted.

Probable cause: The constant calculation mode is intended to multiply or divide a number by a fixed value stored in memory. If this mode is active, entering a number and then pressing an operation key other than the standard addition may trigger a multiplication. Also, ensure you are using the correct keys: for a simple addition, you should use the [+]1 or [+]2 key depending on the chosen totalizer, not a special function key.

Procedure for using simple addition:

Enter the first amount to add
Press the [+]1 key (or [+]2 for the second totalizer)
Enter the next amount
Press [+]1 (or [+]2) again
Continue for all your additions
To obtain the result, press [T]1 or [T]2 (Total key)

If the problem persists: It is possible that a key is faulty or physically stuck, or that a memory function is programmed on your machine. Press the [C/CE] key twice to completely reset the calculator (this clears all contents, including totalizers and Grand total memory). Then test a simple addition to check that normal operation is restored. If addition still triggers a multiplication, consult a specialized calculator repair technician, as this may indicate a hardware malfunction or modified internal programming.

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