๐ How to Know If the Fault Is in the Electronic Board? A Practical Guide to Measuring the Most Important Electronic Components Accurately
In the world of industrial maintenance, technicians and electricians often face a stopped machine and are immediately confronted with the big question:
Is the fault in the electronic board, or in another part of the machine?
Answering this correctly is the difference between a successful repair and a costly delay.
In this article, we’ll walk you through a practical and engaging step-by-step approach to determine if the fault is truly in the board. Then, we’ll show you how to measure its key components like a pro using a multimeter.
๐ ️ First: How to Determine If the Problem Is in the Electronic Board?
✅ 1. Start With Safety
Before any testing:
Disconnect power completely.
Wear appropriate PPE (gloves, insulated tools, safety glasses).
Discharge capacitors to avoid electric shock.
✅ 2. Perform a Visual Inspection
Use your eyes first. Look for:
Burn marks or blackened areas on the board.
Swollen or leaking capacitors.
Broken chips or cut tracks.
If you notice any of these signs, the board is highly likely to be faulty.
✅ 3. Check the Incoming Voltage
Use a multimeter to measure voltage entering the board from the power source.
Example: Is 24V DC or 230V AC present?
If no voltage is present, the problem is external to the board.
✅ 4. Observe the Output Signals
Does the board issue commands? Do lights turn on? Do relays click?
If voltage is entering but the board isn’t outputting anything, it may be silent or dead.
✅ 5. Test the Board in Another Machine (If Available)
Use the same type of board in a similar machine.
If it works: the fault is external.
If it doesn’t work: the board is faulty.
๐ง Second: How to Measure the Key Components on the Board?
You don’t need a lab just focus, patience, and a digital multimeter. Here are the essential components you should test:
๐ 1. Resistors
Measurement mode: ฮฉ (Ohm).
How to test: Place the probes on each side of the resistor.
Expected result: Matches the written or color-coded value.
Common faults: 0 or ∞ reading → burned or shorted resistor.
๐ 2. Capacitors
Measurement mode: Capacitance (ยตF) or resistance (if checking charge/discharge).
How to test: Best to desolder at least one leg for accurate reading.
Expected result: Value close to the one printed on it.
Common faults: 0 or ∞ → capacitor is dry or shorted.
> ⚠️ Always discharge capacitors before testing.
๐ 3. Diodes
Measurement mode: Diode test.
How to test: Red probe on anode, black on cathode.
Expected result: 0.5V–0.7V in one direction only.
Common faults: Reading in both directions or no reading at all → damaged diode.
๐ 4. Transistors
How to test: Like two diodes between Base-Collector and Base-Emitter.
Expected result: One-way conductivity per pair.
Common faults: Always 0 or no reading → faulty transistor.
⚡ 5. Relays
Coil resistance: Typically between 200ฮฉ and 1000ฮฉ.
Contact testing: Use the multimeter to see if the relay changes state when activated.
Common faults: Open coil or contacts not switching.
๐ง 6. Voltage Regulators (e.g., 7805, 7812)
How to test:
Pin 1 = VIN.
Pin 2 = GND.
Pin 3 = VOUT.
Expected result: Output voltage matches specification (5V, 12V, etc.).
Common faults: No output or very low output → regulator is damaged.
๐ Final Pro Tips:
Don’t rely on visual inspection alone test with a multimeter.
Record your measurements for reference.
Be methodical; don’t jump randomly between components.
If unsure about a component, desolder and test it out of circuit.
✨ Conclusion:
Being able to tell whether a fault comes from the electronic board or another part of the system requires method, experience, and accurate measurements. And with a solid understanding of how to test key components, you'll work faster, more confidently, and with greater precision.
For industrial maintenance technicians and electricians, these skills aren’t just tools they’re the language of the machine's heart.
