I've recently taken to poking at the internals of Control4 home automation equipment in my free time. I was able to locate an inexpensive HC-300 which I wouldn't feel bad about taking to pieces. When powered, it would boot successfully but made an extremely audible high-pitched whining noise. My initial diagnosis was an ailing switched-mode power supply.
There are several Phillips screws on the bottom which must be removed to open the unit up. Four are hiding under the two rubber feet which run back to front. Use care when peeling the rubber up as it doesn't stick back down on its own very well. After undoing all of the screws the bottom plate can be removed which frees the top housing to slide off.
Upon opening the unit up I was greeted with a rather tragic power supply board and connecting leads.
The AC to DC power supply is marked Phihong PSA15LN3-XXX. I prodded the output section with a multimeter and measured +5VDC. Thankfully this is a bog standard Phihong PSA15LN3-050-R board which can be had for under $20 (Mouser part number 552-PSA-15LN3-050-R). It's important to find the +5VDC output variant of this board as it comes in +12VDC, +15VDC, and +24VDC variations as well. I also ordered a replacement two-pin socket for the DC power lead to replace the socket that got a little too toasty.
After everything was installed there was no more audible noise when powered.
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