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I'm repairing a Breville Smart Grinder circuit board and found that the issue is due to a bad capacitor. I have removed the said capacitor (C15 in the schematic below) and I am now wondering how to find its capacitance value in order to replace it. The schematic:

enter image description here

I can remove C14 and measure its value but do you have any idea if I can retrieve the value by calculation (I know the values of the resistors) or by the role of the capacitors in the circuit?

Thank you

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    \$\begingroup\$ Measure C14. They will be identical. And R19 = R21, R20 = R22 as a crosscheck. But the actual issue may be something else altogether. \$\endgroup\$
    – user16324
    Commented Sep 30, 2020 at 13:59
  • \$\begingroup\$ I agree as to finding the value but the switch or switches may be what caused the capacitor to fail. It’s similar to old breaker point ignition. If the points became worn or there was too larger a gap or a gap too small, the huge voltage spikes could cause the condenser (a capacitor) to fail. I’d replace both caps and both switches to avoid a comeback. \$\endgroup\$
    – Jason Burchell
    Commented Mar 23, 2023 at 1:09

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If you measure or know the resistor values, and observe the capacitor voltage charging and discharging waveforms with an oscilloscope when pushing and releasing buttons, the capacitor value can be calculated from the RC time constant. So it might be easier to remove the working capacitor and measure it, if you have a device that can measure capacitor values.

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