A coworker of mine who works remotely about 100 miles from the office, and whom I consequently don’t see face-to-face very often, has been talking to me for probably close to a year about a) giving me his old not-believed-functional XBox with cables and controllers, and b) taking some of the retired 2TB hard drives out of my former NAS solution. By a miracle of happenstance, last week we both happened to be in the same city, so we effected an exchange, and it’s led to an interesting (and, maybe, ongoing) journey of debugging.
The original problem he reported was that the unit simply wouldn’t power on; it showed a red ring around the eject button. However, when I first plugged it in, the unit powered up immediately [this is a malfunction in itself; the device is supposed to stay off until power or eject is pressed], showed a blinking amber/green ring as it attempted to read a disk, and basically appeared to work mostly normally – no errors on screen, it came up to the regular “please set date and time” UI. However, on closer inspection it did have a different problem: pressing the eject button would power the unit off instantly, and pressing the actual power button did nothing at all. I managed to get the tray to eject by holding down the button – I don’t have any disks to test with it, but the hard drive and other parts of the system all seem to be working fine.
Some research led to this XBox repair page (among others talking about the same issue). I was kinda hoping that the problem would be a simple thing like a stuck pushbutton, but it is assuredly not the case. Even with the pushbutton board disconnected from the motherboard, the unit still powers up by itself when plugged in. So I disassembled the whole thing, and cleaned the affected trace area with 50/50 isopropyl alcohol/water. This left what look to be a couple of holes in the outermost trace (see picture), but it’s hard to tell – continuity check is OK, but that doesn’t mean there aren’t shorts I can’t see. Testing at this point – with only the power supply, fan and front button board connected to the motherboard – showed it to be working perfectly! Perhaps this “corrosion” issue had just been shorting a couple of traces, and removing the corrosion fixed the issue?
Nothing is that simple, of course. While I was reassembling the unit, I got as far as reinstalling the motherboard and reconnecting the optical drive, but not the hard drive yet. A test at that point showed that the unit now behaved worse – it would only power up for a fraction of a second – just long enough for the optical drive to start its initial spinup. However, disconnecting the power/control cable from the optical drive made the unit behave completely normally. So this doesn’t really feel like a flaky couple of front panel input channels – it seems more like either a short in the optical drive (making it draw too much current and sending the PSU into shutdown) or a problem with the power supply itself. Letting the unit “cool off” (unplugged) for a minute or two and plugging it back in let it stay powered up for maybe a second, but on subsequent powerup attempts it would switch off instantly.
At this point I decided to put everything back together so I wouldn’t lose any parts, and mull over the matter some more. (Let’s keep in mind here that an entire working XBox, no cables/controllers, can be had for $25 on eBay). After full reassembly, I tested again, and it was still acting as described above…
… until I left it alone for a few hours downstairs, which is (though this may be irrelevant) a great deal cooler than my upstairs office. Now it’s back to exactly the same behavior it showed when I first received it. So either it is a temperature issue, or the iso/water mix I used to clean the PCB dissolved some salts and formed a slightly conductive bridge, which has now dried up and ceased to allow current flow. In any case, my next step will be to scope all the power rails across the odd behavior, to see if any of them are sagging – but that will be a test for some future weekend.