I recently bought a Linksys WRT54G v.1.0 from someone on ebay 'as-is'. The price was right and I was in the mood for a little project. It came with the old 5v2a power supply and when plugged in, only the 'power' and 'diag' lights came on. They were blinking. The unit didn't respond to pings.
Figuring it was bricked from a firmware upgrade gone bad, I soldered in a JTAG header and tried to fix it with the HairyDairyMaid debricker utility. I backed up CFE and NVRAM, then erased both, then flashed it. Whilst flashing, both the 'power' and 'diag' lights stopped blinking and stayed lit. But at about 5% of the way through the CFE flash, it froze. After monkeying with it, I found that by cycling power to the router when it froze, the flashing process would continue. I ended up using this method to flash everything, including the KERNEL, to the point where the HairyDairyMaid software reported success in all cases. However, upon disconnecting from JTAG and cycling power again, it was the same old story: blinking 'power' and 'diag' lights and no ping response.
About this time, I noticed that something was loose in the power supply. It rattled around inside when shaken. So I tested the power supply w/ a multimeter which reported that it still did put out 5v.
Some research indicated that these units can handle more voltage than what they're rated for. I noticed that the power adapter for my DSL modem was12v. It fit into the receptacle on the WRT54G, so I plugged it in and was greeted with a POP sound. I unplugged it immediately. There was a burnt circuitry smell, but no smoke and no visible damage to the PCB or any chips
- even under magnification.
Well, upon closer inspection of the power adapter, I noticed it's output is12v AC, and the router needs DC. Of course the router doesn't respond to any power supply now and the lights no longer come on at all. Clearly a boneheaded move on my part, but what's done is done.
My question: don't most electronic devices like this have some sort of fuse protection on the board, to protect the circuitry from boneheads like myself? Does anyone know if there's a varistor or something on the board that I could just replace to bring it back from the dead?