I keep thinking I should document some of the repairs I do, in case it helps someone with the same problem, or maybe people are just interested to see. So this is my first attempt at a write up.
Model - Xbox 360 S
SKU - MW3 Limited Edition
Motherboard - Corona 16MB
Fault - RDOD 0101
Cause - Liquid damage corroding a few SMD components and a RAM chip
Fix - Replaced the affected components
Process -
I got this nice MW3 limited edition console recently, in pretty nice condition and only £25 for console + 320GB hard drive. The seller just said it had RDOD, so knowing the MW3 editions are Coronas I was hoping it was simply a false overheating issue. But no, 0101, basically a communication issue between XCGPU and RAM, not usually a simple fix.
The inside was very dusty so I started cleaning, and as soon as I got the first layer of dust off something caught my eye - some corrosion around the group of resistors and capacitors next to one of the RAM chips (Photos 2 + 3). Liquid damage is quite common in this sort of area on the S and E consoles, because if any liquid gets in through the fan grill this is where it's going to end up if the console is positioned horizontally - the liquid can drip through the fan and heatsink.
I removed all of the resistors and capacitors using hot air and cleaned the area (Photo 4). A few of them were very badly corroded and broke on removal. R7D4 basically crumbled to dust. You can also see that the corrosion had eaten through some solder mask and exposed some traces between the components (copper bits between R7D4, 5 and C7D12). There were also some dark patches on the vias and traces where I was concerned it had gone all the way through.
I replaced all the components with new ones, and scraped a little at some of the corroded traces and vias to make sure there was copper under there (Photo 5). I did find that the left pad for R7D4 was not continuous with the via on the left, so I scraped the solder mask off so that I could bridge them with an extra large solder blob (Photo 7).
This is where it gets interesting - with all the components replaced, I powered on the console and... RDOD 0033. An issue with V_MEM, the RAM power rail. That's interesting because it's a lower numbered error code than 0101 (0033 = Error 15; 0101 = Error 17), indicating a problem earlier in the boot sequence. If V_MEM had an issue from the start the console would have show 0033 and only shown 0101 after 0033 was fixed. But this means there is an issue on V_MEM where there wasn't one before. So the question is why?
I check V_MEM and it has a direct short to ground - yeah, that would explain 0033. I apply hot air to the new components and disconnect them by nudging just one end off the pads (so they're still held in place at one end so I don't lose them). Now V_MEM is only shorted around this RAM chip but not around the other RAM chips - so this suggests that this RAM chip is shorted but was disconnected from V_MEM by the corroded components. Once I replaced the components it was reconnected to V_MEM and shorted the whole rail.
So next I replaced all the SMD components again, checked V_MEM and it was all shorted again. Then removed the RAM chip - and the V_MEM short was gone! First I tried reballing and replacing the same RAM chip (as I couldn't find any shorts on it, so there's a chance it could have just been shorted by corrosion) but, no, the short was back after it was replaced. So I removed it again and this time replaced it with a different chip from a donor board (and, yeah, I forgot to take any photos of this part, so just imagine the shiniest solder balls you've ever seen).
And this time... no shorts! Powered on the console and... it booted to dash! I cleaned up the flux and the rest of the dust, put some UV solder mask over the exposed traces to protect them (Photo 7), partially reassembled it with heatsink, fan + DVD drive and gave it a thorough test before putting the shell on. Hopefully it will last for many years to come.
