How can I perform in-circuit testing of capacitors and resistors effectively?

Hi everyone,

I’m Emmanuel Katto from Uganda, I’m looking for recommendations on the best methods for in-circuit testing of capacitors and resistors, especially when diagnosing and refurbishing multiple boards. I’ve heard about ESR meters, but I’m having trouble finding quality ones online. Additionally, using a scope and function generator has been suggested.

For my needs, quick and repeatable testing is crucial. Could anyone with experience using ESR meters, scope and function generators, or smart tweezers for in-circuit testing share their recommendations? I’d appreciate any insights or suggestions on effective tools or methods.

Thank you in advance for your help!

Best regards,
Emmanuel Katto Uganda

The piece of equipment you most likely want for reliable measurement of capacitors (and inductors) is commonly called an “LCR Bridge” or “LCR Meter”. It’s basically a more capable multimeter which includes “complex” currents and voltages as well. These often allow you to measure the series resistance too.

The one I have is a Keysight U1733C, but these are not cheap. There are plenty of alternatives, but usually with some tradeoff (lower measurement accuracy, can’t measure small values, fixed test frequency etc). It’s worth being careful with this as these specifications can affect the readings significantly.

But that will only get you a measurement of what you can see - if the component is in-circuit then you will measure the total effect of the circuit. I’m not sure of a good way around that other than educated guestimating if you know the circuit schematic, or doing a small mod to somehow isolate what you’re trying to measure.