Xbox 360 No Power

Board is unresponsive to power button

  1. 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

  2. Standby Power Rails
    • Check power rails in the following order:
    • Power Rail Source Location: Phat Location: Trinity Location: Corona/Winch
      V_5P0STBY Standby 5V directly from PSU FT8N1 FT6M1 FT6M1
      V_5P0DUAL 5V, switched between V_5P0STBY and V_5P0 FT1R2 FT1N9 FT1N9
      V_3P3STBY 3.3V, created from V_5P0STBY FT5N1 FT5M1 DB5A2
      V_1P8STBY 1.8V, created from V_5P0STBY FT5N2 FT5N2 N/A
      V_1P2STBY 1.2V, created from V_5P0STBY N/A N/A DB3C2
    • 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 C5B1, C5B2 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

  3. 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 Y3B1 for 25 MHz single-ended clock
      • This is as far as we can check STBY_CLK circuit on these boards

  4. 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

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