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Old 15th May 2005, 03:50 AM   #1
9am53 is offline 9am53  Canada
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Default resistors of a lower power rating

if the resistors in my amp are originally rated at 1/2 watt, and I replace them with 1/4 watt ones, what can happen? they work, I am just thinking that tey may fry...
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Old 15th May 2005, 03:57 AM   #2
rpapps is offline rpapps  Antarctica
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They can overheat, change in resistance value or simply go open circuit.
Measure the voltage accross them and use the e^2/r formula to work out the power being dissipated.
It's good practise for reliability to use resistors rated at least twice the power they are actually dissipating.

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Old 15th May 2005, 04:06 AM   #3
kmtang is offline kmtang  Canada
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Simply measure the voltage across the resistor. Then calculate the power dissipation of it with P=V*V/R.

Most of the time people put a higher power rating. With this calculation, you should know exactly what it should be.

For reliable operation, you should allow at least 50% margin on the resistor wattage rating.

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