Trying to track down the source of the screeching in my recently acquired Sharp X68000 Super... I've already replaced the fan in the PSU with a quiet Noctua, which reduced the fan noise significantly (bearings were shot on the original), but the PSU squeals when in use. Which is a shame, as it works perfectly and, otherwise, the system is in tip top condition. It's just the noise that's an issue:
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Every electrolytic has been replaced, but common wisdom says to up the capacitance of the two 5600uF filtering caps to 6800uF. So I'll try that.
My collection database and technical wiki:
https://www.target-earth.net