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Old 09-20-2021, 06:04 PM   #54
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Default Re: xbox 360 blowing mosfet

See this diagram:

With the adapter plugged into the Xbox, you should be getting ONLY the voltage shown in PURPLE. This means you should also get 5V on the right leg of the 3.3V STBY regulator (the one circled in purple and labeled "STANDBY POWER"). This should be happening regardless of whether the regulator is actually on the board or not, as it's a direct connection to the power brick's 5VSB rail.

The multimeter readings in diode mode of the regulators don't mean much. The only way to test these regulators is to either have them installed on the board and supply them with power or build a test circuit on a breadboard and see if they work (look up "1117-33" and "1117-18" voltage regulator datasheets and copy the typical application circuit from it.)

That said, a good test to perform with your multimeter is to set it on lowest resistance test mode (typically 200 Ohms for manual multimeter) and measure the resistance between where the arrow points to 3.3V and any GND connection on the motherboard. Do this with the power adapter -disconnected- from the motherboard. Also check the 1.8V regulator the same way. If you have a low resistance under 100-200 Ohms on any of these regulator output pins, you might have shorted something else downstream when you were performing the mod.

Last edited by momaka; 09-20-2021 at 06:06 PM..
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