Hello. I signed up just to reply to this thread. I purchased a few of these chinese W5100 boards and have been going nuts trying to get them running. The resistor network is definitely the issue.
There are a few ways to re-work it without the 49ohm network.
I used 47ohm radial resistors and tried 2 different methods. Both were successful.
Hopefully my pictures and notes help.
- Remove the resistor network labeled 511 behind the RJ45 socket. I used a hotair station. Careful hand iron would work with some chipquick solder probably.
- On the bottom solder shortened leads to pins 1,2,3,6. (Watch pin3, space the lead carefully)
- combine the loose ends of 1,2 and then 3,4.
- Run hookup wire from the junction of 1,2 to the cap behind the rj45 socket, on the end closest to the socket.
- Run hookup wire from junction of 3,4 to the cap to the right of the 102 resistor network, also to the side closest to the RJ45 socket.
1. Remove the resistor network labeled 511 behind the RJ45 socket. I used a hotair station. Careful hand iron would work with some chipquick solder probably.
2. Fold 4x 47 ohm resistors so they are radially configured. Snip the leads about 3mm from the bottom of the resistor. Then tin the ends with solder
3. Installing the resistors in an alternating pattern(for space) you can tack them to the surface mount pads. I was able to tack one side at a time and then go back to add more solder, being careful not to bridge any pads. I found removing the RJ45 socket made this much easier
4. The side of the pads away from the RJ45 socket are common to the capacitors, so you can double up and cross over the pads for each pair. Meaning pad1 and 2 can share the opposite side and 3,4 respectively.
The first method seems to be the easiest using 1/4w resistors. I have some 47ohm surface mount resistors at work that I may try, but with what I had at home, this worked quite well.
Here are some images of the re-work. I tested using the Webserver sample code and it worked immediately.
Link to Imgur gallery (images are larger than 1mb) http://imgur.com/a/JrPFD
Hope this helps!