1. Introduction
Thank you for choosing the BENETECH GM760 Digital LCD PH Meter. This high-precision, waterproof device is designed for accurate measurement of pH levels and temperature in various solutions. Featuring an easy-to-read LCD display, automatic calibration, and temperature compensation, it is ideal for a wide range of applications including laboratories, aquariums, hydroponics, and water quality testing. Please read this manual thoroughly before use to ensure proper operation and to maximize the lifespan of your device.
2. Safety Information
- Always handle the glass electrode with care.
- Do not immerse the entire meter in water; only the electrode tip is designed to be submerged.
- Keep the device out of reach of children.
- Store the meter in a cool, dry place when not in use.
- Do not attempt to disassemble or modify the device, as this will void the warranty.
- Dispose of batteries according to local regulations.
3. Package Contents
Upon opening the package, please verify that all items are present and undamaged:
- BENETECH GM760 PH Meter (or selected model: GM761, GM762, GM763)
- User Manual
- Button Battery LR44 1.5V * 3 (may be pre-installed)
- Protective cap for electrode
4. Product Overview
Familiarize yourself with the components and controls of your PH meter:
Figure 1: Front view of the GM760 PH Meter with protective cap.
Figure 2: Front view of the GM760 PH Meter with electrode exposed.
Figure 3: Hand holding the GM760 PH Meter, showing the LCD display and control buttons.
Key Components:
- LCD Display: Shows pH and temperature readings, battery indicator, and hold function.
- Power Button (On/Off): To turn the device on or off.
- HOLD Button: To freeze the current reading on the display.
- ℃/℉ Button: To switch between Celsius and Fahrenheit temperature units.
- CAL Button: For initiating the automatic calibration process.
- Electrode: The sensor tip for measuring pH and temperature.
- Protective Cap: Covers the electrode when not in use to keep it moist and protected.
5. Setup
5.1 Battery Installation
The GM760 PH Meter uses 3 LR44 1.5V button batteries. If the display does not turn on or shows a low battery indicator, replace the batteries:
- Locate the battery compartment, usually at the top of the meter.
- Open the battery compartment cover.
- Insert three LR44 1.5V button batteries, ensuring correct polarity (+/-).
- Close the battery compartment cover securely.
5.2 Initial Preparation
- Remove the protective cap from the electrode tip. If the electrode is dry, soak it in distilled water for 10-15 minutes before first use.
- Rinse the electrode with distilled water before each use.
6. Operation
6.1 Powering On/Off
- Press the Power button to turn the meter ON.
- Press and hold the Power button for a few seconds to turn the meter OFF. The device features power-off memory, retaining previous settings.
6.2 Taking Measurements (pH and Temperature)
- Turn on the meter.
- Immerse the electrode tip into the solution to be tested. Ensure the electrode is fully submerged but do not immerse the entire meter.
- Gently stir the solution and wait for the reading to stabilize on the LCD display. The display will show both pH and temperature.
- After measurement, rinse the electrode with distilled water and replace the protective cap.
Figure 4: GM760 PH Meter measuring a solution.
6.3 Calibration (Automatic)
The GM760 features automatic calibration. Regular calibration ensures accuracy. It is recommended to calibrate the meter before first use, after long periods of inactivity, or if readings appear inaccurate.
- Prepare standard buffer solutions (e.g., pH 4.00, pH 6.86, pH 9.18).
- Turn on the meter and immerse the electrode into the first buffer solution (e.g., pH 6.86).
- Press the CAL button. The meter will automatically recognize the buffer solution and calibrate itself. Wait for the reading to stabilize and for the calibration indicator to confirm completion.
- Rinse the electrode with distilled water.
- Repeat the process for other buffer solutions (e.g., pH 4.00 and pH 9.18) if multi-point calibration is desired for higher accuracy.
6.4 Data Hold Function
During measurement, press the HOLD button to freeze the current reading on the display. Press it again to release the hold and resume live measurement.
6.5 Temperature Unit Switch
Press the ℃/℉ button to toggle the temperature display between Celsius and Fahrenheit.
7. Maintenance
7.1 Cleaning the Electrode
- Always rinse the electrode with distilled water before and after each use to prevent contamination.
- If the electrode is heavily soiled, gently clean it with a soft brush and a mild detergent solution, then rinse thoroughly with distilled water.
7.2 Storage
- Always replace the protective cap after use. The cap should contain a small amount of electrode storage solution or pH 4.0 buffer solution to keep the electrode moist. Never store the electrode dry.
- Store the meter in a cool, dry place away from direct sunlight and extreme temperatures.
7.3 Battery Replacement
Refer to section 5.1 for instructions on replacing the LR44 batteries when the low battery indicator appears or the device fails to power on.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Meter does not turn on | Dead or incorrectly installed batteries. | Replace batteries (LR44 x 3) and ensure correct polarity. |
| Inaccurate or unstable readings | Dirty electrode, dry electrode, or meter needs calibration. | Clean the electrode, soak in distilled water, or perform calibration. |
| Slow response time | Electrode is dry or aged. | Soak electrode in storage solution or distilled water. If problem persists, electrode may need replacement. |
| Temperature reading incorrect | Sensor issue or environmental factors. | Ensure the meter has acclimatized to the environment. If problem persists, contact support. |
9. Specifications
The following table outlines the technical specifications for the GM760 series PH meters:
Figure 5: Product Parameters for GM760 and GM761.
| Parameter | GM760 | GM761 (for comparison) |
|---|---|---|
| PH measuring range | 0.0 ~ 14.0pH | 0.00 ~ 14.00pH |
| PH resolution ratio | 0.1 | 0.01 |
| PH measuring error | ±0.1% | ±0.1% |
| Temperature measuring range | 0~60℃ (32~140℉) | |
| Temperature resolution ratio | 1℃ | |
| Temperature error | ±1.0 ℃ | |
| Power supply | Button Battery LR44 1.5V * 3 | |
| Display | LCD large screen display | |
| Working environment temperature | 0~60℃ | |
| Working environment humidity | ≤85%RH | |
| Backlight | White backlight | |
| Dimension (Size) | 41*42*189.23mm | |
| Weight | 83.8g | |
| Calibration | Automatic calibration | |
| Function | Solution temperature compensation | |
Figure 6: Measurement Range and Working Environment.
10. Applications
The BENETECH GM760 PH Meter is suitable for a variety of applications, including but not limited to:
- Industrial processes
- Agricultural testing
- Drinking water quality monitoring
- Medical and laboratory research
- Aquariums and hydroponics
Figure 7: Range of Applications.
11. Warranty and Support
The BENETECH GM760 Digital LCD PH Meter comes with a 1-year warranty from the date of purchase. This warranty covers manufacturing defects and malfunctions under normal use. It does not cover damage caused by misuse, accidents, unauthorized modifications, or improper maintenance.
For technical support, warranty claims, or service inquiries, please contact your retailer or the BENETECH customer service department with your purchase details.
