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Today we’ll be taking a look at the Netcomm NB1300 Rev2 ADSL Ethernet Modem which is an 10/100 Ethernet & USB ADSL modem, quite an old one back from 2003 and a bit dusty too.


Two screws later and we’re in.

Looks like the layout is pretty relaxed, lots of space left over. We’ve got a fair few electrolytic capacitors which are all branded Teapo, we have a single chip solution and interestingly there’s a VCXO. Date code is 35th week of 2003.

This device runs off 12VAC so we have a bridge rectifier going through two 0 ohm resistors (option of 2 inductors) to an UTC MC34063 DC-DC converter with a couple of 470uF around plus 2x LD1117 LDOs; nothing too fancy.

The main chip is a Conexant AccessRunner CX82310 which has a 168 MHz ARM940T processor, 10/100 Ethernet MAC, USB 1.1, integrated ADSL transceiver/AFE/Line Driver and could also be hooked up to an 802.11b through the PCMCIA interface. I believe it’s running from the the 35.328Mhz VCXO.

The memory we have is an MX MX29LV160 16Mbit Flash and an ISSI IS42S16400 64Mbit SDRAM.

For the ethernet side, we have a Delta LF8505 for the isolation transformer with a Micrel KS8721B 10/100 transceiver running with a 25 MHz crystal. There isn’t anything special for the USB side and the RJ11 side has the usual gas discharge tube and transformer, no other chips needed as the line driver is done by the Conexant. Apart from that we just have a logic chip, a 74HC14D hex inverting schmitt trigger near the bottom left.

And that’s all.

One Response to “Inside the Netcomm NB1300 Rev2 ADSL Ethernet Modem (Dated 2003)”

  1. ANAND RAJ says:


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