Test Equipment-Techniques for finding bad components on Printed Circuit Boards (PCB)


Adding diagnostics equipment to enhance your test capabilities is an important part of any electronic repair environment. There are many techniques that can be used to find bad components on a Printed circuit boards (PCB), from a servo drive, or controller. Some of the more common testing equipment are: Multimeters, Huntrons, and capacitors. 


A multimeter, multitester, or a VOM (Volt-Ohm meter), is an electronic measuring instrument which combines several measurement functions into one unit. It is used for basic fault finding and field service work, or to measure at a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems.

4Digital multimeters (DMM, DVOM) display the measured value in numerals, which eliminates parallax errors, and may display a bar of a length proportional to the quantity being measured. Modern multimeters are often digital due to their accuracy, durability and extra features. In a digital multimeter the signal under test is converted to a voltage and an amplifier with electronically controlled gain preconditions the signal.

DMMs are able to offer as standard the basic measurements that would typically include:

  • Current (DC) -(Typically low current without an amp probe)
  • Current (AC)-(Typically low current without an amp probe)
  • Voltage (DC)
  • Voltage (AC)
  • Resistance

3Most DMMs are able to offer additional test capabilities. These may include some of the following:

  • Capacitance
  • Temperature
  • Frequency
  • Transistor test – hfe, etc
  • Continuity (buzzer)
  • Auto-ranging-selects the correct range for the quantity under test so the most significant digits are shown.
  • Auto-polarity-direct-current readings, shows if the applied voltage is positive or negative
  • Sample and hold-which latches the most recent reading for examination after the instrument is removed from the circuit under test.
  • Current-limited tests for voltage drop across semiconductor junctions, facilitating testing diodes and a variety of transistor types.
  • Graphic representation of the quantity under test making go/no-go testing simple and allows spotting of fast-moving trends.
  • Low-bandwidth oscilloscope
  • Automotive circuit testers, including automotive timing and dwell signals.
  • Simple data acquisition features to record minimum and maximum readings over a given period, a number of samples at fixed intervals.
  • Integration with tweezers for surface-mount technology.
  • A combined LCR meter for small-size SMD and through-hole components.


Analog multimeters use a microammeter whose pointer moves over a scale calibrated for all the different measurements that can be made. Although multimeters are far more common, analog multimeters are still preferable in some cases, for example when monitoring a rapidly-varying value.



Huntron Tracker power-off circuit board test uses analog signature analysis to detect and isolate component faults on boards beyond power-on functional testing. By comparing Tracker signatures from a working circuit board to the signatures of a non-working board, you can troubleshoot down to the component level.

7The benefits:

  • Test Circuit Boards that cannot be powered on
  • Schematics or documentation is unnecessary due to Analog Signature Analysis using Comparison troubleshooting
  • Reduce risk to the PCB from further damage if powered up
  • Screen PCBs for catastrophic problems before adding power


A capacitor is a passive two-terminal electrical component used to store energy electrostatically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric.  A capacitor stores energy in the form of an electrostatic field between its plates. Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass. In analog filter networks, they smooth the output of power supplies. In resonant circuits they tune radios to particular frequencies. In electric power transmission systems they stabilize voltage and power flow.


One of the best techniques are visual. Professional electronic technicians will use their eyes to first examine  the equipment for  contaminated areas on the board. The experts will search for any components showing contaminates such as discolor or aging. These components can be easily spotted by a trained eye and are a great place to start when searching for the damaged areas affecting your equipment.

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  1. In my thirty plus years as a machinist I have only worked with one E.T. that could do diagnostics at board level on CNC machine. great information!

  2. Nice post….It is very informative and great post.

  3. Good tips, im looking how to use a multimeter and find your site, thanks

  4. With the advancement of technology we need to develop the capabilities of finding the bad components on PCB which also plays an important role in any electronic repair. At BEST we also offer various techniques for PCB repair as its services along with tools i.e PCB Repair Tools.

  5. Really a great post. Nowdays, there are a number of techniques used to find bad components in printed circuit boards. The test equipment are nicely explained in this post. Thanks for sharing such a great post with informative techniques of finding bad components in PCBs.

  6. Thanks for the informative content, Cammy!!! The Discrete Component Testing is one of the best methods to troubleshoot PCB components. However, it’s a time-consuming process but to test each individual component such as the resistor, capacitor, diode, transistor, inductor, MOSFET, LED gives us the guarantee for the next step. Just like Troubleshooting before final assembly is important similarly inspection of assembled pcb is also important to get the quality product.

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