Have a unique issue with your BP-120 not covered here? Check the Casio subreddit or the manual PDF links above for schematics and repair logs.
: Keep the two metal sensors clean. Finger oils or dirt can cause "ERR" (Error) messages during readings.
To take a reading, the watch requires two points of contact: The case back must be touching your wrist. Casio Bp 120 Manual
Movement during measurement. Repeat test. Real-world fix: The internal o-rings dry out. Open the cuff unit, apply silicone lubricant to the valve piston, and reassemble.
Enter your (ideally taken from a professional medical cuff). The watch uses this data as a calibration offset to calculate your readings more accurately. 4. Time and Date Adjustment In Timekeeping Mode , hold Adjust until the seconds flash. Have a unique issue with your BP-120 not covered here
We live in an era of frictionless technology. An Apple Watch manual is three sentences: "Pair with phone. Wear it. Don’t swim with the leather band." The Casio BP 120 manual, by contrast, is a text of friction . It demands patience. It rewards obsession. It contains troubleshooting trees for sensors that measure altitude, temperature, and direction simultaneously, without any connectivity to the outside world.
: This model typically uses a CR2016 lithium battery. If the display dims or the BP sensor fails to activate, it is time for a replacement. Finger oils or dirt can cause "ERR" (Error)
First, a quick history. The Casio BP-120 was released in the early 1990s. It features a digital watch on one side and a detachable blood pressure monitor with an inflatable cuff on the other. Unlike modern smartwatches that use optical sensors, the BP-120 uses via an air pump.
The watch measures the time it takes for a pulse of blood to travel from your heart to your finger—a metric known as Pulse Transit Time (PTT). It then uses this data to calculate your systolic and diastolic blood pressure. Essential Setup and Calibration