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As its been a while since I did any hardware stuff (other than some dabbling in Arduino), I decided I would try and resuscitate a bricked 941n router. I had given it to the staff to fiddle with, but they needed a push in the right direction for where to start.

First I needed tools.
Luckily China is pretty awesome when it comes to getting electronic bits and pieces so most of what I needed was a mere Taobao away.

As the crap soldering irons in the office weren’t going to hack it, my first purchase was a decent soldering iron.
I took a look at the Wellers (which I used in a previous lifetime), and decided that the pricing was a little too steep for my liking!
Taobao had plenty of cough, cough ‘clone’ Hako 936’s though, so I bought one of those, 10 tips and some solder for a little less than 200RMB delivered to the office.

I could have gone to buy it over in the electronics mall over in Beijing lu, but seriously, Taobao is easier.

While I was at it, I also orderd a Rek DC power supply, and some JTAG cables.
The PSU isn’t totally useful for router hacking, but we do have a lot of people that forget to bring laptop chargers with them, so it will come in handy for that. Looks pretty nifty too.

Hako 936 and Rek DC PSU

Next up was a serial to ttl adaptor, as the TP-Link uses TTL voltage apparently, and I needed to convert into standard pc serial.
I bought 2 adaptors, one USB one, with rather crappily made headers, and a rather nicer serial one with pin’s.

As I’m rather crap at soldering, I totally expected things to bork something up, but amazingly I got the headers installed relatively easily, and even managed to bridge pad (R356) to enable serial first go (as per the wiki).

I plugged in my serial adaptor to the computer, and powered up the router.
Suprisingly everything worked first time around, and I got some serial output in HyperTerminal.

A few nanoseconds later I got to experience again how much I hated HyperTerminal.
Grumble cpu usage grumble frozen input grumble mutter,… and installed PuttyTel instead.

Putty also seems to autodetect the kernel speed nicely (as boot changes from 9600 to 115,200baud), which is a bonus.

I still need to time it right so I can catch the u-boot in time to stop it, and, I also still need to reflash it, but the hard part is done!

Total cost – roughly 250RMB for parts (soldering iron, tips, serial ttl adaptor, pin headers, jtag stuff etc), plus about an hour of time, most of which emcompassed clearing my desk enough so I could solder ๐Ÿ™‚

I’m all setup for more journeys into equipment though, and I can now completely recover borked equipment handily.

Useful pages:
http://wiki.openwrt.org/inbox/tp-link.tl-wr941nd (Pinouts)
https://forum.openwrt.org/viewtopic.php?id=18354&p=1 (Thread on TL-WR941 hacking)

Firmware files:
http://downloads.openwrt.org/snapshots/trunk/ar71xx/

Taobao shopping:
http://item.taobao.com/auction/item_detail-db1-3fbe7be878a7aa35dd4ec1e4260113e8.jhtml (RS232 TTL)
http://item.taobao.com/auction/item_detail-db2-3c9886e66da40119a6c72fe03c4b8d38.jhtml (Hakko 936 + tips)
http://item.taobao.com/auction/item_detail-0db1-4fbc4e80f96ae37dbd34b9cb466aa642.jhtml?cm_cat=0 (Wiggler JTAG)