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May 8, 2025
Every now and then, a console comes across my workbench that just won't play nice. This time, it was a Microsoft Xbox 360 Corona. Within minutes, its temperature would climb to a toasty 78°C, and the fan would roar to life, sounding less like a whisper and more like a jet engine preparing for takeoff.
I figured this was a simple case, a quick fix, and I would have it running silently and cool in no time. Little did I know, this was the beginning of a long and frustrating journey.
My first thought was thermal paste, but in taking the system apart I found a couple of potential culprits. The fan connector was a little loose, and the heatsink wasn't fully tightened down. I made those adjustments, reassembled the system, and fired it up. Could it be that easy?
The fan was still roaring, the temperature was still climbing. My initial hope was quickly dashed. I knew there had been some corrosion on the heatsink that had been cleaned previously, maybe it was affecting the thermal conductivity? Maybe I had just botched the thermal paste application?
I decided to take the heatsink from a known-good system I had for parts and swap it in if this one didn't look good. Time for another teardown.
I disassembled the system again and inspected the thermal paste application on the APU and everything seemed to be okay. The paste was well-spread, though maybe a little too generous. Still, I wouldn't expect that to cause a catastrophic issue. I cleaned the old paste from the heatsink and the top of the APU and found no signs of corrosion on the underside.
The mystery deepened. If it wasn't the heatsink and it wasn't the paste, what was left? I had a sinking feeling I knew the answer: the thermal paste under the IHS had probably turned to a useless crust.
But wanting to avoid delidding I tried my spare heatsink with some false hope. I reassembled the unit and booted it up. Within minutes, the temperature was at 77°C. The fans weren't as loud as before, but the temperature was still too high. My best guess had to be correct—the paste under the IHS was done for.
Ugh. It was time to delid the APU.
With a deep breath and a steady hand, I delidded the APU, successfully getting it apart without nicking a single component. I cleaned the old, crusty paste from the die, applied a fresh coat, and reassembled everything.
The console booted up, and I eagerly watched the temperature.
The temperature started at 78°C almost immediately and climbed to 85°C. The fan ramped up to get it back down, and I realized with a heavy heart that for whatever reason, this particular Xbox 360 was still a hot runner.
I took the system apart again just to see how the fresh paste looked under the IHS. The amount of paste seemed to be good, with full coverage so I cleaned it all up and repasted it the same way one more time. I powered up the system and started playing a CD to give the system something to do. Within a few minutes, the temperature was back at 85°C. The console was mocking me. I was at a dead end. Or so I thought.
Then I remembered something that I wish I had remembered sooner. Corona units have a relatively common failure mode tied to resistors which form part of the temperature probe system. They are supposed to be 0-ohm, but as they degrade, their resistance can increase, leading to false temperature readings.
With nothing left to lose, I broke out my multimeter.
I found the following: R4D3: 0.8Ω, R4D4: 1Ω, R4D6: 3.2Ω, R4D8: 50Ω. Bingo. These weren't supposed to have any resistance at all! The console was faking a fever because the resistors were giving it bad information.
I carefully removed all six of the temperature-related resistors and replaced them with solder bridges.
I powered up the system, and the temperature readout was a beautiful sight to behold: it started in the high 30s °C and then after running for a while, it settled at a comfortable 68°C. The fan was a quiet whisper once again.
It was a long road, filled with failed attempts and false hopes. I delidded the APU, swapped heatsinks, and repasted more times than I care to admit. But in the end, the culprit wasn't a lack of cooling; it was a case of the console misreading its own temperature.
This little adventure is a perfect reminder that sometimes fixing things requires a lot of persistence. The Xbox 360 is back in action, running cool, quiet, and ready to play for years to come.
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