Power Up Basics (Xbox Original)

starting with the power board of the console to check it is working to at least the standby (non switched) rails remove all components from the power supply so it is not connected to the hdd, disc drive or motherboard connect the mains power plug into the socket on the back of the console going into the power board minimum boot in order to boot the system needs all power rails present (except audio 9v) no dvd or hdd are needed to get to the boot up animation at least, but if you want to try and successfully boot from a hard drive you must also have a dvd present otherwise it can cause the boot animation or dashboard to crash if you want to just get to the power led stage of boot to see if you get past frag, you can boot with nothing at all connected, and you should see the boot up animation and service error message that the dvd or hdd are missing (error 12 or 7 usually) although the xbox will also look for a default xbe from the dvd drive, if there is no hdd present it will not boot from the dvd drive so, you must have a working hdd to be able to load from dvd (even with a mod chip installed) the drive can be unformatted, or correctly formatted, but it cannot be corrupt or absent if the hdd is not formatted with the right partitions and the dvd you are loading wants to write to it (such as the xbox installer) it will hang indefinitely or fail with something like error 21, so really it is advised to have a fully working drive testing 110/230v input take your multimeter and test on voltage ac and measure you are getting power over both sides of the fuse warning be very careful not to touch the probes together or touch any exposed metal as there is mains voltage running through the power board that can kill warning be very careful not to touch the probes together or touch any exposed metal as there is mains voltage running through the power board that can kill put the com/black probe on the neutral pin, and then voltage/red probe on each side of the fuse one at a time if you get 110/230v (depending on your region) on both sides of the fuse, your power board is at least getting mains power into it if it does not, disconnect the power, leave it 10 minutes so it is safe to touch and work on testing fuse set your multimeter into continuity mode and test the fuse it should read around 0 to 3r and beep if it reads 0l the fuse is blown and needs swapping if all that is good, move on to checking the output of the power board connector, making sure it is disconnected from the console testing standby rail with mains ac applied , but the connector not inserted into the motherboard, the only rail you will get is the standby rail (3 3v or 5v depending on version) this is 3 3v on version 1 0 to 1 5 and 5v on v1 6 below is a v1 6 power supply, so the 3 orange wires (plus another orange wire on the other row you cannot see) are the 5v standby rail voltages take your multimeter, turn it to voltage dc , and test the black and orange wires for 5 5v (it drops to 5v once connected to motherboard) if you do not get this rail, something on your power board is damaged and needs fixing power supply pins each version of the xbox has different connectors on a v1 6 version below, the orange 5v and the blue 3 3v power ok rails should be 5v and 3 3v respectively, even before connecting to the motherboard psu out of standby to bring the psu out of standby and enable the 3 3/5/12v rails, the white wire must be given 3 3v this is done by the smc once the power button is pressed connect the front panel cable (in this case the yellow cable) into the motherboard and press the power button on the console to trigger power on this will get read by the smc/motherboard and the smc/motherboard once it detects a power button press should then send 3 3v to the power on (white wire) the power supply should then output all other rails (the 3 3v, 5v and 12v rails) on v1 0 to 1 5 you can simply short the brown/grey/purple 3 3v standby pin to the power ok (white) pin on v1 6, you can use a basic voltage divider off the orange 5v standby rail to trigger the power supply to fully juice up all rails regardless of the smc for testing purposes if you like place a 1k resistor between the power on pin and ground , and a 4 7k resistor between the 5v rail and the power on pin (make sure to do this with the power off, and make 100% sure the connections are good if the 1k resistor is not installed correctly you will be sending 5v directly into the 3 3v rail potentially damaging something if the 1k resistor is not installed correctly you will be sending 5v directly into the 3 3v rail potentially damaging something confirm these voltage rails are all active with a multimeter when pressing the power button or bypassing the power on make sure to have your probes on the wires before pressing the power button as if there is a fault you should still see the power rails come up momentarily for example, go on the yellow 12v wire and press the power button it should show 12v instantly, and if there is a failure it will collapse shortly after psu power ok once the power on (white wire) is sent to 3 3v, the psu should output 3 3v on the power ok (blue wire) to indicate the psu is working and all rails are stable the smc reads this power ok voltage and resets the cpu/gpu/mcpx fan spin make sure to connect the fan next, and when pressing the power on button the first thing that happens is the case fan starts to spin this is even before you get leds on the front panel this is a good first indicator of power getting to the system and the power supply working if you get fan spin, it is highly likely your power supply is good