D-Link DSL-504T teardown and project proposition

[necercis]

D-Link DSL-504T/EU V.A1

I have got this router for over than 6 years. It was used in ADSL connection and provided connection for 2 computers and lan printer. Recently it started to disconnect form WAN on random matter so the decision was made and newer model was bought.

As I had some more time I looked into this device. The casing is held together by two nice threaded screws and a pair of catches. It opens very easily no worries about breaking the plastic. And there is board. Design is nice, clean and simple.
After quick look through components I noticed two burnt capacitors (C155, C156) and but for them everything seems to be undamaged.

The board is single sided and consists of bunch of caps, diodes, tranformers, crystals and a bunch of chips. There are also some pinouts that look like JTAG and serial connectors. I have not confirmed that.

Chips:

• Atmel's AT49BV322A (http://www.atmel.com/dyn/resources/prod_documents/doc3308.pdf), it is a low voltage 32-megabit memmory.
• Hynix HY57V281620HCT-H 128Mbit ram module
• IP175A 5Port 10/100 Ethernet Integrated Switch (http://www.icplus.com.tw/pp-IP175A.html)
• integrated cpu tnetd73000gdu (I have found simply no info on this part, it looks like some TI product but their search engine is crap), it seems to be MISP

And that would be all about teardown. It is time for fun part.

I want to make it into something useful. Of course it can be still used as 4 port Ethernet switch but I want more, maybe a tiny SSH server for my internal network or blinds/curtains controller. I do not care if I accidentally blow it up, it may happen and I want to learn something useful. As it is my first attempt with hacking and I have little knowledge about routers I would like to ask for advice.

The main drawbacks are: low computing power of the CPU and mainly SMD design. Also after looking through router modding pages no one really takes insight into hacking D-Link routers.

Any advices how to get with it? Or ideas for better usage?
If I get it done it will be posted.

~necercis

[nyo]

How do you know the caps are burned?

[necercis]

They look like something bad happened there. Due to lack of good meter with capacity measurement I checked with el cheapo one only for short circuit and it did not occured, but I do not trust this meter. The resistance is over 20 MOhms, as it is highest range of my meter. Also take a better look.

~necercis

[nyo]

oh, the smd ones, I see, thanks

[codeboy2k]

That CPU is a part of TI's AR7 family.  Specifically, I think it's the same as the AR7WRD .

This is used in a lot of  ADSL routers.  I didn't look , but there might be something hacked for it already on the net that you can flash onto the board using the JTAG port.

If you find something for the AR7WRD with source available you could do your own port to your  modem, if someone hasn't already done it.

[the_raptor]

I bet if you trace those caps they are near the phone line input. ADSL modems are more resistant in general to transient voltages then the old 56k softmodems were (when I worked in a computer shop you could guarantee you would see a bunch of these the day after a lightning storm) but they still blow occasionally.