1 Answer
To check the voltage on a printed circuit board (PCB), you generally need a digital multimeter (DMM). Here's a simple step-by-step guide to measure the voltage:
### 1. **Prepare the Multimeter:**
- Set the multimeter to the correct voltage range. For most common PCBs, you should set the meter to **DC voltage (V with a straight line or dotted line under it)**, unless you're measuring AC voltage (which is indicated with a tilde ~).
- If your multimeter is auto-ranging, it will select the correct range automatically. If not, choose a range that’s higher than the expected voltage (e.g., set it to 20V for measuring 5V or 12V).
### 2. **Connect the Multimeter Probes:**
- **Black probe**: Insert it into the common (COM) terminal.
- **Red probe**: Insert it into the voltage (VΩmA) terminal.
### 3. **Check Ground Reference:**
- Find a ground point on the PCB, typically the negative terminal of a power supply or a ground plane. The black (negative) probe of the multimeter should be connected to this ground.
### 4. **Measure the Voltage:**
- Place the **red probe** (positive) on the point where you want to measure the voltage.
- If you're measuring a component’s voltage, like a capacitor or IC, carefully place the red probe on the component's pin or lead you want to measure. For traces, you can touch the probe directly on the PCB trace or via pad.
- Read the voltage value displayed on the multimeter.
### 5. **Observe Polarity:**
- The multimeter will show a **positive (+)** or **negative (-)** sign in front of the voltage value.
- **Positive voltage**: This means the point you're measuring is higher than ground.
- **Negative voltage**: This means the point you're measuring is lower than ground (or reverse polarity).
### Tips:
- **Be cautious**: Always measure voltage on the PCB with the power on, but avoid shorting components with the probe.
- If you're measuring a **low-voltage circuit** (like 5V or 3.3V), ensure the multimeter's range is set to an appropriate setting (like 20V or 200mV).
This method will help you check the operating voltage of various parts of your PCB.
### 1. **Prepare the Multimeter:**
- Set the multimeter to the correct voltage range. For most common PCBs, you should set the meter to **DC voltage (V with a straight line or dotted line under it)**, unless you're measuring AC voltage (which is indicated with a tilde ~).
- If your multimeter is auto-ranging, it will select the correct range automatically. If not, choose a range that’s higher than the expected voltage (e.g., set it to 20V for measuring 5V or 12V).
### 2. **Connect the Multimeter Probes:**
- **Black probe**: Insert it into the common (COM) terminal.
- **Red probe**: Insert it into the voltage (VΩmA) terminal.
### 3. **Check Ground Reference:**
- Find a ground point on the PCB, typically the negative terminal of a power supply or a ground plane. The black (negative) probe of the multimeter should be connected to this ground.
### 4. **Measure the Voltage:**
- Place the **red probe** (positive) on the point where you want to measure the voltage.
- If you're measuring a component’s voltage, like a capacitor or IC, carefully place the red probe on the component's pin or lead you want to measure. For traces, you can touch the probe directly on the PCB trace or via pad.
- Read the voltage value displayed on the multimeter.
### 5. **Observe Polarity:**
- The multimeter will show a **positive (+)** or **negative (-)** sign in front of the voltage value.
- **Positive voltage**: This means the point you're measuring is higher than ground.
- **Negative voltage**: This means the point you're measuring is lower than ground (or reverse polarity).
### Tips:
- **Be cautious**: Always measure voltage on the PCB with the power on, but avoid shorting components with the probe.
- If you're measuring a **low-voltage circuit** (like 5V or 3.3V), ensure the multimeter's range is set to an appropriate setting (like 20V or 200mV).
This method will help you check the operating voltage of various parts of your PCB.