Xbox 360 No Power

Xbox 360 No Power

If the Xbox 360 is unresponsive to the power button, the board is died-died.

General

 * Try a known good RF board and power supply
 * Check if an SMC heartbeat is present on the test point for DBG_LED0
 * Heartbeat consists of the signal blipping high about once a second
 * If heartbeat is missing, continue below

V_5P0STBY

 * Check if V_5P0STBY is present
 * If missing, check if V_5P0STBY is shorted
 * If it is, check decoupling capacitors and V_5P0DUAL circuit
 * This rail comes directly from the power supply
 * Check 5V on DC jack
 * If missing, check DC jack

V_3P3STBY

 * Check if V_3P3STBY is present
 * If missing, check if V_3P3STBY is shorted
 * If it is, check the regulator and decoupling capacitors
 * Check circuit components
 * Replace the regulator

V_1P8STBY

 * This rail is not present on Corona, Waitsburg, Stingray, and Winchester
 * Check if V_1P8STBY is present
 * If missing, check if V_1P8STBY is shorted
 * If it is, check the regulator and decoupling capacitors
 * Check circuit components
 * Replace the regulator

V_1P2STBY

 * This rail is only present on Corona, Waitsburg, Stingray, and Winchester
 * Check if V_1P2STBY is present
 * If missing, check if V_1P2STBY is shorted
 * If it is, check the regulator and decoupling capacitors
 * Check circuit components
 * Replace the regulator

V_5P0DUAL

 * Only check this rail if all above rails are present
 * Check if V_5P0DUAL is present
 * If missing, check if V_5P0DUAL is shorted
 * If it is, check the regulator and USB ports
 * Check if VREG_V5P0_SEL is high
 * If it is, check regulator input resistors
 * If resistors are fine, replace the regulator
 * If low, SMC is not alive, continue below

Standby Clock

 * Xenon, Zephyr, Falcon, Jasper, Tonasket, and Trinity
 * Check STBY_CLK for 48 MHz clock signal
 * If bad/missing signal, check crystal for 27 MHz
 * Check STBY_CLK series resistor
 * Replace clock chip (Cypress or HANA)
 * Corona, Waitsburg, Stingray, and Winchester
 * It is not possible to check STBY_CLK
 * Check crystal 25 MHz

SMC Reset

 * Check if SMC_RST_N is present
 * If missing, check series resistor and pulldown
 * If still missing, replace ANA/HANA/KSB

SMC and Flash

 * Read the nand image and check that it is valid
 * Try writing a known good image and check if the board powers on
 * Try reading back a written image and verifying it matches
 * If image read back does not match, replace the flash
 * Some boards using Phison or eMMC may have high failure rates
 * The Phison or eMMC must be replaced, or the board must be converted to use a nand
 * Ensure to program the correct image back when finished
 * If needed, retrieve the CPU Key and LDVs via XeLL and rebuild the image

Southbridge

 * If all else fails, replace the Southbridge