XDK LEDs Tutorial

Learn how to add XDK LEDs to Phat HDMI Motherboards

Xbox 360 XDK Motherboards come with 2 LEDs installed, one for CPU CheckStop and one for SMC “Heartbeat”.

This tutorial will cover how to add these LEDs to non-XDK motherboards (or XDKs missing them).

Tutorial by Octal450


The CPU CheckStop LED will work on any Phat motherboard. It is illuminated when the CPU is running.

Component List:
– ON Semiconductor MMBT2222 General Purpose Transistor – Q8B6
– 2K Ohm 0402 Resistor – R8B6
– 1K Ohm 0402 Resistor – R8A5
– Green (or another color) 0603 LED – D8B4

D8B4, Q8B7, R8A5, and R8B6 Installed:
Located at right hand side of fan cutout, top side

DBG_LED0_LED: (SMC Heartbeat)

The SMC Heartbeat LED will work on any non-Xenon motherboard. It does not work on Xenon motherboards.
It flashes slowly when in standby and FullOn states, and flashes rapidly when transitioning between those states.

Component List:
– Texas Instruments SN74LVC1G14DCK (SC70-5 package) Single Schmitt-Trigger Inverter – U1U1
– 249 Ohm 0402 Resistor – R1U3
– Yellow (or another color) 0603 LED – D1F1

If you can’t find 249 Ohm (or 250 Ohm) for R1U3, use slightly higher resistance, I used 270 Ohm.

D1F1 Installed:
Located at front left corner of board, top side, in front of HDD port

R1U3 and U1U1 Installed:
Front right corner of board, bottom side, about underneath where D1F1 is on the top