Zephyr has fixed his Roku power supply by replacing the C5 47μF capacitor and the 3842B integrated circuit.
A few notes:
The capacitor that I replaced was a 105Â°C, 35V 47μF capacitor. So it was already a high-temp one. I couldnâ€™t find a high-temp one, so I replaced it with a 85Â°C, 100V 47μF capacitor. Itâ€™s larger so perhaps the increased surface area will handle the heat a bit better. Its maximum rated voltage (100V) is also far greater than the operating voltage (30V) in the circuit, unlike the prior part (35V). Remember you need a capacitor with radial
The existing power supply can be easily removed by 5 screws. But once removed from the Roku cabinet, a metal shield still hides the two parts that I replaced. This shield is anchored to the power supply circuit board with a solder joint in each of the four corners. Itâ€™s necessary to remove those joints, one of which is a solder blob shared with two other capacitors. There are also two screws that anchor several high power transistors to the metal cover for heat sinking purposes. You'll need to at least loosen those screws; I didn't need to completely remove them. Obviously upon replacing the IC and capacitor, youâ€™ll need to resolder the cover back onto the power supply board.
The components are tightly packed, but not too difficult to work with. Thankfully the capacitor and the 3842B are at the top center edge of the power supply board. Remove the power supply from the Roku and most definitely donâ€™t have it plugged in while you are working on it.
The Roku case screws are very difficult to remove. The screws are also â€œsoftâ€, so itâ€™s easy to strip the Phillips heads on them. Be careful! I suggest a few drops of Liquid Wrench on each and letting it sit for a half hour before trying a P1 Phillips bit.
I ordered parts from digikey.com. They have an extra $5.00 fee if your order is less than $25 along with some shipping charges. I encountered similar fees from all other suppliers. My parts list:
565-1151-ND 47UF 100V ELECT SMG RADIAL CAPACITOR (0.37/each)
497-4602-5-ND IC CURRENT-MODE PWM CTRLR 8-DIP ST3842B (1.16/each)
I avoided the $5.00 extra fee by getting a few things I needed for other projects.