How temperature affects resistance in real world applications

[Alan]

Imagine you’re trying to fix a circuit that runs perfectly when it’s cold, but starts acting up as it heats up, and suddenly the ohms just don’t make sense. What are some real-life examples, quick tests, or handy rules of thumb you rely on when heat begins to alter resistance?

 

[TheOhmBreaker]

Cold solder joints or microcracks can seem fine at first but fail under heat due to thermal expansion. Use a heat gun on suspicious joints and watch for resistance spikes, that’s your issue. Reflow it properly, and the problem will be gone.

 

[ohmsweetohm761]

Check the resistance when cold, then after it warms up. A big difference often points to thermal issues, like cracked traces or bad connections. Using freeze spray can help pinpoint trouble spots while the circuit is powered and acting up.

 

[solderandchill]

Carbon resistors change with heat, and semiconductors can be even more sensitive. If a circuit works cold but fails when hot, I usually start by checking the electrolytic capacitors, they often fail first in hot conditions. Also, keep an eye out for discolored components; that's a sign they’re overheating gradually.