My computers PSU makes a high pitch whine. Its quite annoying. I opened it up and listened for the noise but couldnt really tell where it was coming from. (It may have been lowest on the AC input filter... maybe i think my mind was playing tricks on me).
Does anyone have any ideas of how to fix this? I have googled this extensivly and just seen a lot of contradicting stuff. Some say its the inductors and some the caps. I tried pushing a rubber eraser against the inductor coils but that didnt help.
FWIW, I think every time I have had something whining, it was either a shorted component causing excessive current or a cap that has failed, causing an unstable circuit.
ESR meter only way to check caps quickly & easily in SWMPS. In circuit & discharged first. Ordinary cap testers & ohm meters are no good. Only other way is replace all caps.
The debate comes up often that capacitance testing does not accurately measure the effectiveness of the capacitor. The ESR meter measures the internal resistances at a given frequency. I specifically just repaired a SMPS circuit that was whining and would start and stop the load constantly. It turned out to be 2 small value caps that tested GOOD out of circuit with a cap meter but tested WAY out of spec with the ESR meter.
The debate comes up often that capacitance testing does not accurately measure the effectiveness of the capacitor. The ESR meter measures the internal resistances at a given frequency. I specifically just repaired a SMPS circuit that was whining and would start and stop the load constantly. It turned out to be 2 small value caps that tested GOOD out of circuit with a cap meter but tested WAY out of spec with the ESR meter.
The simple thing is if you are going to remove them for testing, than you may as well put new ones back in as the cost is bugger all, and saves the hassle of testing, very rare the large caps will be the problem normally always the little ones that cost nothing much.
You could guess all year and replace half the components in the PSU and never find it. Get yourself a microphone and using spectrum analyzer software like DL4YHF's Audio Spectrum Analyser
watch the spectral intensity as you move the microphone around the PSU, you should be able to locate the exact source within a few minutes.