1. Introdución
The Extech MO257 is a pinless moisture meter designed for non-invasive measurement of moisture content in various building materials, including wood, wallboard, sheetrock, cardboard, concrete, plaster, and mortar. Its pinless design allows for measurements without causing surface damage. The device features a measurement depth ranging from 0.78 inches (20mm) to 1.6 inches (40mm) below the surface, user-settable alarm levels with audible and visual indicators, and a triple backlit LCD for clear readings.
2. Características clave
- Non-invasive measurement of moisture levels in wood, wallboard, sheetrock, cardboard, concrete, plaster, and mortar.
- Measurement depth from 0.78 inches (20mm) to 1.6 inches (40mm) below the surface.
- Two user-settable alarm levels with an audible beeper and visual (flashing "RISK" or "WET") indicators.
- Triple backlit LCD for enhanced visibility in various lighting conditions.
- Moisture Icons provide a visual reference for low, medium, and high levels of moisture.
- Audible Alert Tone increases in frequency as moisture level rises.
- Data Hold Function to freeze readings on the display for convenient recording.
3. Información de seguridade
Please read and understand all safety instructions before operating the Extech MO257 moisture meter. Failure to follow these instructions may result in injury or damage to the device.
- Do not attempt to open or modify the meter. There are no user-serviceable parts inside.
- Keep the device away from water and excessive humidity to prevent damage.
- Evite deixar caer o medidor ou sometelo a impactos fortes.
- Store the meter in a dry, cool environment when not in use.
- Dispose of batteries according to local regulations. Do not mix old and new batteries.
4. Compoñentes do produto
The Extech MO257 Pinless Moisture Meter consists of the main unit and its integrated sensor. Familiarize yourself with the following parts:

- Pinless Sensor Ball: Located at the top of the meter, this spherical sensor is used to detect moisture without penetrating the surface.
- Pantalla LCD: A triple backlit screen that shows moisture readings, alarm indicators, and other operational information.
- Botón de encendido: Úsase para acender e apagar o dispositivo.
- Botóns de función: Buttons for setting alarms, adjusting parameters, and activating data hold.
- Compartimento de batería: Located on the rear of the device, housing the AA batteries.
5. Configuración
5.1. Instalación da batería
- Localice a tapa do compartimento das baterías na parte traseira do medidor.
- Deslice a tapa cara abaixo para abrir o compartimento.
- Insert three (3) AA batteries, ensuring correct polarity as indicated inside the compartment.
- Volva colocar a tapa do compartimento da batería deslizándoa cara arriba ata que encaixe no seu lugar.
5.2. Acendido inicial
Press the power button to turn on the meter. The LCD will illuminate, and the device will perform a brief self-test before displaying the ready-to-measure screen.
6. Instrucións de funcionamento
6.1. Facer unha medida
Para medir o contido de humidade:
- Ensure the meter is powered on.
- Place the pinless sensor ball flat against the surface of the material you wish to measure. Ensure full contact for accurate readings.
- The moisture reading will be displayed on the LCD. The meter will automatically adjust for different material densities within its measurement range.
- Observe the moisture icons (low, medium, high) and listen for the audible alert tone, which will increase in frequency with higher moisture levels.

6.2. Using the Data Hold Function
Press the "HOLD" button (if available, or refer to specific button on device) to freeze the current reading on the display. Press it again to release the hold and resume live measurements.
6.3. Setting Alarm Levels
The MO257 allows you to set two user-defined alarm levels. Consult the full manual for detailed instructions on navigating the menu to set these thresholds. When the measured moisture exceeds a set alarm level, the meter will provide an audible beep and flash "RISK" or "WET" indicators on the display.
7. Mantemento
7.1. Limpeza
Wipe the meter with a dry, soft cloth. Do not use abrasive cleaners or solvents. Ensure the sensor ball is clean and free of debris for accurate readings.
7.2. Substitución da batería
When the battery indicator appears on the display, replace the batteries as described in Section 5.1. Prompt battery replacement ensures optimal performance and accuracy.
7.3. Almacenamento
If storing the meter for an extended period, remove the batteries to prevent leakage. Store the device in its pouch case in a cool, dry place, away from direct sunlight and extreme temperatures.
8 Solución de problemas
This section addresses common issues you might encounter with your Extech MO257 moisture meter.
| Problema | Causa posible | Solución |
|---|---|---|
| O medidor non se acende. | Baterías gastadas ou instaladas incorrectamente. | Check battery polarity; replace batteries if necessary. |
| Lecturas inexactas ou inconsistentes. | Poor contact with surface; dirty sensor; environmental interference; material outside measurement range. | Ensure full contact with the surface; clean the sensor ball; move away from strong electromagnetic fields; verify material is within specified measurement capabilities. |
| A pantalla está escura ou parpadea. | Batería baixa. | Substitúe as pilas. |
| Audible alarm not working. | Alarm feature disabled or volume too low (if adjustable); moisture level below alarm threshold. | Check alarm settings; ensure moisture level exceeds set threshold. |
If the problem persists after attempting these solutions, please contact Extech customer support for further assistance.
9. Especificacións
| Parámetro | Valor |
|---|---|
| Número de modelo | MO257 |
| Tipo de medida | Pinless, Non-invasive |
| Measurement Depth | 0.78 a 1.6 polgadas (20 a 40 mm) |
| Fonte de enerxía | 3 pilas AA (incluídas) |
| Voltage | 4.5 voltios (DC) |
| Dimensións do produto | 2.5 x 1.1 x 9.2 polgadas |
| Peso do elemento | 10.58 onzas (0.3 quilogramos) |
| Fabricante | Extech |
| Tipo de montaxe | Montaxe en superficie |
10. Garantía e soporte
Extech Instruments products are designed for reliability and performance. For information regarding warranty coverage, technical support, or service, please refer to the official Extech websitio web ou póñase en contacto co seu departamento de atención ao cliente. Garde o recibo da compra como proba de compra para reclamacións de garantía.
Para obter a información de soporte máis actualizada, visite a Tenda Extech en Amazon or the official Extech Instruments websitio.





