Introduction
The Extech MO55 is a versatile combination pin/pinless moisture meter designed for quick and accurate moisture measurements in various materials. It is an essential tool for building restoration projects, moisture detection in floors, tiles, and behind walls, and analyzing the effects of water leakage. This manual provides detailed instructions for the proper use, maintenance, and troubleshooting of your MO55 moisture meter.
Figure 1: Extech MO55 Combination Pin/Pinless Moisture Meter. This image shows the front view of the green and orange meter with its digital display showing "99.9%".
Key Features
- Dual Measurement Modes: Offers both pin (invasive) and pinless (non-invasive) measurement capabilities for diverse applications.
- Material Versatility: Measures moisture levels in wood, wall board, sheet rock, cardboard, concrete, plaster, and mortar.
- Moisture Icons: Provides visual indicators for low, medium, and high moisture content levels on the display.
- Audible Alert: Features an audible tone that increases in frequency as moisture levels rise, aiding in quick detection.
- Pinless Depth: Non-invasive mode can read moisture up to 1 inch (25mm) below the surface.
- Data Hold: Allows freezing of the current reading on the display for convenient viewing.
- Compact Design: Lightweight and easy to handle for on-site measurements.
Figure 2: Close-up of the Extech MO55 display showing moisture level icons. The display indicates a 50.0% reading with three water droplet icons, signifying a high moisture level.
Figure 3: Close-up of the Extech MO55 display highlighting the battery life indicator and the button to toggle material type. The display shows a 50.0% reading and a full battery icon.
Figure 4: Close-up of the Extech MO55 display showing the audible alert icon and the button to toggle display lock and audible alert. The display shows a 50.0% reading and an active audible alert icon.
Setup
Battery Installation
- Locate the battery compartment on the back of the MO55 meter.
- Open the battery compartment cover.
- Insert one 9V battery, ensuring correct polarity (+/-).
- Close the battery compartment cover securely.
Initial Power On
Press the power button (⑂) to turn on the device. The display will illuminate, and the meter will be ready for use.
Operating Instructions
Selecting Measurement Mode (Pin vs. Pinless)
The MO55 offers two measurement modes:
- Pin Mode: For direct contact measurements using the integrated pins. Ideal for wood and building materials where penetration is acceptable.
- Pinless Mode: For non-invasive measurements, suitable for detecting moisture behind surfaces like tiles or walls without causing damage.
To switch between modes, refer to the mode selection button on your device. The display will indicate the active mode.
Taking Pin Measurements
- Remove the protective cap from the pins.
- Gently push the pins into the material you wish to measure. Ensure both pins make firm contact.
- Read the moisture content percentage displayed on the screen.
- The audible alert will beep faster as moisture levels increase.
- Press the Data Hold button to freeze the reading if needed.
Figure 5: A hand holding the Extech MO55, with its pins inserted into a wooden stud to measure moisture content. The display shows a reading of 17.4%.
Figure 6: A hand holding the Extech MO55, with its pins inserted into an OSB (Oriented Strand Board) panel, likely checking for moisture. The display shows a reading of 28.5%.
Taking Pinless Measurements
- Ensure the meter is in pinless mode.
- Place the back of the meter flat against the surface of the material.
- Move the meter slowly across the surface to scan for moisture.
- Observe the moisture content percentage on the display. The meter can read up to 1 inch (25mm) deep.
- The audible alert will indicate increasing moisture levels.
Figure 7: A hand holding the Extech MO55, using its pinless sensor against a wall surface to detect hidden moisture. The display shows a reading of 35.7%.
Interpreting Moisture Readings
The MO55 provides visual moisture icons (water droplets) on the display to indicate low, medium, and high moisture levels. Consult the material-specific moisture content chart (often found on the back of the device or in the full user manual) for accurate interpretation of readings for different materials.
Maintenance
Cleaning
Wipe the meter with a dry, soft cloth. Do not use abrasive cleaners or solvents. Ensure the pins are clean and free of debris after each use.
Battery Replacement
When the battery indicator shows low power, replace the 9V battery as described in the "Setup" section. Remove the battery if the meter will not be used for an extended period to prevent leakage.
Storage
Store the MO55 in a cool, dry place, away from direct sunlight and extreme temperatures. Always replace the protective cap over the pins when not in use to prevent damage and injury.
Figure 8: The Extech MO55 moisture meter shown with its protective cap removed and placed beside it, revealing the two measurement pins.
Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Meter does not power on. | Dead or incorrectly installed battery. | Replace the 9V battery, ensuring correct polarity. |
| Inaccurate readings. | Dirty pins (pin mode), improper contact, or measuring outside specified range. | Clean pins. Ensure firm contact with material. Verify material type is within meter's range. |
| Audible alert not working. | Audible alert feature is turned off. | Press the button to toggle the audible alert on (refer to Figure 4). |
| Meter turns on accidentally in pocket/bag. | Power button is too sensitive. | Store the meter in a protective case or position it to prevent accidental button presses. |
Specifications
| Feature | Detail |
|---|---|
| Model Number | MO55 |
| Product Dimensions | 2.6"W x 6.7"H (2.6 x 1.2 x 6.7 inches) |
| Item Weight | 4.32 ounces |
| Power Source | 1 x 9V battery (included) |
| Pin Wood Moisture Range | 5 to 50% |
| Pin Building Material Range | 1.5 to 33% |
| Pinless Wood Moisture Range | 0 to 99% |
| Pinless Building Material Range | 0 to 99% |
| Moisture Icons | Yes |
| Data Hold | Yes |
| Audible Alert | Yes |
| Color | Green |
| Manufacturer | Extech |
| Country of Origin | China |
Figure 9: A comparison table showing specifications for various Extech moisture meter models, including MO50, MO53, and MO55, detailing their measurement ranges, features like moisture icons, data hold, and audible alerts.
Warranty and Support
For warranty information and technical support, please refer to the official Extech website or contact their customer service. A comprehensive user manual in PDF format is also available for download:
