1. Introduction
The Extech 412355A is a precision instrument designed for calibrating process devices and accurately measuring DC process signals. It functions as both a current and voltage calibrator and meter, capable of sourcing and measuring signals from 0 to 24mA or as mV in voltage ranges. Its robust design, featuring an oyster case with a flip-up display, makes it suitable for both handheld and benchtop applications.
Figure 1: The Extech 412355A Calibrator/Meter. This image shows the device in its open, operational state, displaying the LCD screen and control buttons for power, mode, unit selection, memory, and zero adjustment. A white cable is connected to the side port.
2. Safety Information
Please read all safety instructions before operating the Extech 412355A. Failure to follow these instructions may result in electric shock, fire, or personal injury.
- Do not operate the device if it appears damaged or if the case is open.
- Ensure correct connections are made before applying power or signals.
- Always use the device within its specified voltage and current limits.
- Refer to the specifications section for detailed operating ranges.
- Replace batteries promptly when the low battery indicator appears to ensure accurate readings.
3. Package Contents
Verify that all items are present and in good condition upon unpacking.
- Extech 412355A Current and Voltage Calibrator/Meter
- 9V Battery (pre-installed or included separately)
- Calibration cable with spade lug terminals
- Carrying case
- Neck strap
- AC Power Adapter
4. Product Features
- Precision source for calibrating process devices and measuring DC process signals.
- Oyster case with flip-up display for versatile handheld or benchtop use.
- Large 3-1/2 digit LCD display for clear readings.
- Intuitive touch keypad for easy operation.
- Displays readings in mA, as a percentage of the 0 to 24mA range, or as mV in voltage ranges.
- Provides adjustable 0 to 24mA and 0 to 10V calibration source.
- Five stored calibration values for quick recall and efficient calibrations.
5. Setup
- Battery Installation:
The device requires a 9V battery. If not pre-installed, open the battery compartment on the rear of the unit, connect the 9V battery to the terminal, and place it inside. Close the compartment securely.
- AC Power Adapter Connection:
For extended use or when batteries are low, connect the supplied AC power adapter to the DC input jack on the side of the calibrator and plug it into a standard AC outlet.
- Connecting Test Leads:
Attach the calibration cable with spade lug terminals to the appropriate input/output jacks on the calibrator based on whether you are sourcing or measuring current/voltage. Ensure connections are firm and correct for the intended measurement or calibration task.
6. Operating Instructions
6.1 Power On/Off
- Press the POWER button to turn the unit on or off.
- The LCD will illuminate and display the last used mode.
6.2 Mode Selection (Source/Measure)
- Press the MODE button to switch between SOURCE and MEASURE functions.
- In SOURCE mode, the calibrator outputs a signal.
- In MEASURE mode, the calibrator measures an external signal.
6.3 Unit Selection (mA, %, mV)
- Press the UNIT button to cycle through the available display units: mA, percentage (of 0-24mA range), or mV (for voltage ranges).
6.4 Adjusting Output/Reading Values
- Use the UP (▲) and DOWN (▼) arrow buttons to adjust the output value in SOURCE mode or to fine-tune settings.
6.5 Memory Functions (MEM/ZERO)
- Press the MEM/ZERO button to access stored calibration values (M1-M5) or to perform a zero adjustment. Refer to the full manual for detailed memory programming instructions.
7. Maintenance
7.1 Cleaning
Wipe the device with a damp cloth and mild detergent as needed. Do not use abrasive cleaners or solvents. Ensure the device is powered off and disconnected from any power source before cleaning.
7.2 Battery Replacement
When the low battery indicator appears on the display, replace the 9V battery immediately to maintain measurement accuracy. Follow the battery installation steps outlined in the Setup section. Dispose of used batteries according to local regulations.
7.3 Storage
Store the calibrator in its carrying case in a cool, dry environment when not in use for extended periods. Remove the battery if storing for several months to prevent leakage.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Device does not power on. | Low or dead battery; AC adapter not connected or faulty. | Replace 9V battery or connect AC power adapter. Ensure AC adapter is functional. |
| Inaccurate readings. | Incorrect mode/unit selection; poor test lead connection; device needs calibration. | Verify MODE and UNIT settings. Check test lead connections. If issues persist, consider professional calibration. |
| No output in SOURCE mode. | Incorrect connections; output value set to zero; internal fault. | Check output connections. Adjust output value using arrow buttons. If problem continues, contact support. |
| Display shows "OL" or "OVERLOAD". | Input signal exceeds device's measurement range. | Disconnect the signal immediately. Ensure the input signal is within the specified range of the calibrator. |
9. Specifications
| Model | 412355A |
| Functions | Current Source/Measure, Voltage Source/Measure |
| Current Range | 0 to 24mA |
| Voltage Range | 0 to 10V |
| Measurement Accuracy | ±0.5% |
| Display | 3-1/2 digit LCD |
| Power Source | 9V Battery (Alkaline), AC Power Adapter |
| Battery Type | Alkaline |
| Dimensions (L x W x H) | 4.2 x 1.8 x 3.8 inches (10.7 x 4.6 x 9.7 cm) |
| Weight | 0.35 Kilograms (12.3 ounces) |
| Operating Temperature | Refer to full product datasheet for details. |
10. Warranty and Support
10.1 Warranty Information
The Extech 412355A Current and Voltage Calibrator/Meter is covered by a 1-year limited warranty from the date of purchase. This warranty covers defects in materials and workmanship under normal use. It does not cover damage resulting from misuse, unauthorized modification, accident, or neglect. Please retain your proof of purchase for warranty claims.
10.2 Technical Support
For technical assistance, troubleshooting, or warranty service, please contact Extech customer support. Visit the official Extech website for contact details and additional resources.
