Xbox 360 No Power

Xbox 360 No Power

No Power
Board is unresponsive to power button

Undo Bad Writes/Check For Faulty NAND


 * The board cannot power on if it cannot load a valid SMC and config from the NAND flash
 * Read NAND and check that the dump is valid
 * If you cannot get valid flash config, continue to next step
 * Replace NAND if flashing a valid image does not yield a valid read
 * Some 4GB Coronas may have a faulty Phison (V2) or eMMC (V4/V6) chip, they must be replaced or downgraded to 16MB
 * This is a common fault, where the controller wears out with extended use of the internal 4GB MU
 * Usually the system will stop saving settings or updating before going completely dead due to controller degradation
 * Can be diagnosed by attempting read/write
 * If faulty, replace Phison/eMMC (U1E3) or convert the board to 16MB
 * Ensure to program the correct image afterwards
 * If the image could not be read/decrypted before replacing, boot XeLL to grab the CPU Key and LDVs and rebuild the image

Standby Power Rails


 * Check power rails in the following order:

Missing V_5P0STBY:
 * This rail comes directly from the PSU. Check DC jack:
 * Phat: J9A1 Pin 8
 * Slim: J7A1 Pin 10
 * Check for shorted filtering caps for V_5P0STBY:
 * Phat: C5B7, C8B1, C9A4
 * Slim: C6A1, C6A4, C6A5

Missing V_5P0DUAL:
 * This rail comes from either V_5P0 or V_5P0STBY, depending on VREG_V5P0_SEL
 * Check regulator pins 5-8 for 5 volts:
 * Phat: U1R1
 * Slim: U1B1
 * Check front and rear USB port pins are not shorted or damaged
 * Check VREG_V5P0_SEL is high (so that V_5P0DUAL will be created from V_5P0STBY)
 * Phat: FT1R1
 * Trinity: FT1P1
 * Corona/Winchester: FT2R1
 * Check 4.75K Ohm resistor:
 * Phat: R1D6
 * Slim: R1P1
 * If VREG_V5P0_SEL is still missing, replace Southbridge:
 * Phat: U2C1
 * Slim: U3D1

Missing V_3P3STBY:
 * Phat:
 * If U5B1 circuit is present:
 * Check U5B1 regulator for shorts, NCP1117 or compatible
 * Check C5B1, C5B2 for shorts
 * If U9C1 circuit is present (Some Phat Jasper Kronos only)
 * Some boards use this different circuit, manufacturer choice, U5B1 circuit will not be present
 * Check U9C1 regulator for shorts
 * Check R9C5: 0 Ohms
 * Check C9C8, C9C10 for shorts
 * Trinity:
 * Check U5A1 regulator for shorts
 * Check R5A11: 0 Ohms
 * Check C5A1, C5A2, C5A3 for shorts
 * Corona/Winchester:
 * Check U5A1 regulator for shorts
 * Check R5A8, R5A12: 0 Ohms
 * Check C5A1, C5A2, C5A3 for shorts

Missing V_1P8STBY:
 * Phat:
 * If U5B2 circuit is present:
 * Check U5B2 regulator for shorts, NCP1117 or compatible
 * Check C5B4, C5B6 for shorts
 * If U9D1 circuit is present (Some Phat Jasper Kronos only)
 * Some boards use this different circuit, manufacturer choice, U5B2 circuit will not be present
 * Check U9D1 regulator for shorts
 * Check R9D4: 0 Ohms
 * Check C9D5, C9D9, C9D10, C9D11 for shorts
 * Trinity:
 * Check U5B1 regulator for shorts
 * Check R5B4: 0 Ohms
 * Check C5B1, C5B2, C5B6, C5B7 for shorts
 * Corona/Winchester: See below, uses V_1P2STBY instead

Missing V_1P2STBY:
 * This rail exists only on Corona/Winchester and is a replacement of V_1P8STBY
 * Check U5A2 regulator for shorts
 * Check R5B4, R5A13: 0 Ohms
 * Check C5A9, C5B1, C5B2, C5B3, C5B7 for shorts

Standby Clock


 * STBY_CLK is created by the ANA/HANA and is used to run the System Management Controller (8051 core) in the Southbridge
 * Phat/Trinity:
 * Check STBY_CLK for 48 MHz single-ended clock:
 * Phat: FT2R2
 * Trinity: FT3N2
 * If bad/missing signal:
 * Check master crystal Y3B1 for 27 MHz single-ended clock
 * Check STBY_CLK resistor for 33 Ohms:
 * Xenon: R3B7
 * Zephyr, Falcon, Jasper: R4B24
 * Trinity: R3B15
 * Replace clockgen chip:
 * Xenon: Cypress CY28517 U3B4
 * Zephyr, Falcon, Jasper: HANA U4C2
 * Trinity: HANA U3B1
 * Corona/Winchester:
 * These boards do not have a STBY_CLK signal as the clockgen was integrated with the Southbridge (KSB), it is generated internally
 * Check master crystal Y3D1 for 25 MHz single-ended clock
 * This is as far as we can check STBY_CLK circuit on these boards

SMC Reset


 * SMC_RST_N must go high in order for the SMC to run
 * It is controlled by ANA/HANA (integrated in Southbridge for Corona/Winchester)
 * Check that SMC_RST_N goes high (3.3V):
 * Phat: J2B1 Pin 5
 * Slim: J2C3 Pin 5
 * Corona/Winchester: If R2C10 is missing, check R2C10 S Pad instead, resistor is not needed
 * If missing signal:
 * Xenon: Replace ANA U4C2
 * Zephyr, Falcon, Jasper: Replace HANA U4C2
 * Trinity: Replace HANA U3B1
 * Corona/Winchester: Replace Southbridge U3D1

Southbridge


 * If all else fails, Southbridge is bad and must be replaced:
 * Phat: U2C1
 * Slim: U3D1