Repair Actions/No Power

See also: Errors and Secondary Error Codes

Note  This page is a technician's reference and is not intended to teach diagnosis and repair of electronic circuits.

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

Standby Power Rails

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