Posted: Fri Dec 30, 2011 14:21 Post subject: Linksys E3000 brick - Serial recovery failed
I'm new on this forum and I need some help with my E3000 router which seems to be bricked. I updated the firmware from Cisco website as per there instructions. After approx. 2 weeks starts to get stuck and I have to reset the router twice a day. Finally, all the lights are not lit, only the power light is flashing. I spent a week reading all your wiki and start to debrick following the Peacock Thread. Because the LAN ports are dead I moved on to serial recovery.
1. I found a DKU-5 Nokia cable (USB-UART Tx line) with OTI6858 chipset, found the drivers and install it (PC found on COM6). Dismantle the USB and found the Tx, Rx and GND on the board (I was surprised that everything was marked).
2. Solder the 3 wires to the router GND (router) to GND, RX (router) to Tx and Tx (router) to Rx (USB adapter). I used the internal 5 pin serial port.
3. Open Putty, configured COM6, 115200, 8, 1, none, none.
4. Start router and very fast press Ctrl-C. Done this plenty of times and I'm sure is fast enough. The message I get is "Error writing to serial device".
5. I measured the voltage between GND and Tx and Rx. All values are equal approx. 3.25 V.
I used a laptop computer with Win7 and Putty.
Now, I'm not sure if I have to try with a CA-42 cable or i have to move on to JTAG. If I have to use JTAG, can anyone tell me if I can use a simple parallel cable (home made as per wiki) or I need a buffered JTAG adapter? Also, the last version of JTAG knows the chipset for E3000 (BCM4718)?
Joined: 26 Jan 2008 Posts: 13049 Location: Behind The Reset Button
Posted: Fri Dec 30, 2011 19:18 Post subject:
I have fixed many E3000's (& 610 V2's).
1st, it is not normal to have to reboot the router twice a day. I would suspect failing hardware. A power supply failure is very common. It may be just weak and not totally fubar. Check the PS before you do anything else.
2nd, assuming that the hardware is intact, no serial output is getting more common with this router. I have not been able to determine the cause.
Lets again assume that you have tested your serial adapter by connecting the tx to the rx of the adapter and verifying that your keystrokes are echo'd in the terminal.
if the hardware is intact, and your adapter is working properly, and you still have no serial output, then you will need jtag to erase nvram "only". Once nvram is erased, then serial should now operate properly.
The problem with the router is that linksys has disabled the jtag circuit on the pcb. You need to bridge 5 pads on the pcb to enable the circuit.
Thanks a lot for your fast reply. I will contact Tornado for JTAG and I will post the status. I changed the PS before the router got bricked because I experience same problem with my old WRT300N, 2 years ago. That time was the power supply faulty.