Reviving the NetComm NB1300 Plus 4

Not long ago, I dug up an old ADSL modem, the NetComm NB1300 Plus 4. I remember that it was working a while back, but suddenly stopped working. Since I had some spare time on my hands, I thought I might want to see what I can do about it.

This can also be used as a fully illustrated, step-by-step guide to the procedure I used in order to revive the ADSL modem.

Signs and Symptoms

I’m assuming we know what a working ADSL modem looks like. You know, like it powers on, and lights blink. But with this one, the power light comes on, but nothing else really works. The nice thing is, when I plug in a LAN cable to the LAN ports, it’ll still light up and make the connection and I think it’ll still work as a 4-port switch. Maybe.

But I don’t just want a 4-port switch, I want to fix it and get the modem back. I searched the internet, and found a possible solution at the Whirlpool forums.

Cause

Reading through most of the posts on the forum, it appears that this can happen at any time with no prior warning. It seems as though the flash memory chip can suddenly lose its data, since it supposedly can be fixed by reflashing it.

How to Repair the ADSL Modem

So let’s go through how I’ve managed to revive this ADSL modem, back to its working order.

Tools and equipment

For this operation, we’ll need:

• A medium-sized Phillips head screwdriver
• A standard jumper connector
• The power adaptor
• A USB-A to USB-B cable
• An ethernet cable
• A blank CD
• A blank floppy
• A computer
• The NB1300_DIY_REPAIR.rar package

Preparing for the operation

Before trying to flash the modem, let’s get our tools ready. Download the NB1300_DIY_REPAIR.rar package, that is required for getting the floppy and the CD. There are also CD-boot alternatives, but that is another story.

So to get started, let’s write the floppy image, “bootable image.IMZ”, to disk. I’m not going to show you how to do it, since you’ll be able to find guides on how to do that in another corner on the internet. Essentially, all I did was “dd if=bootable image.IMZ of=/dev/fd0″ under linux of course.

With the CD image, use your favourite CD writing application capable of reading the Nero .nri CD image format. Naturally, I’ve used Nero Burning Rom. Just write the image onto the disk, and you’ll be good to go. Since the image was only about 20MB, I’ve used a CD-RW to avoid wasting the rest of the CD capacity.

Reflashing the modem

The NetComm modem operates in one of two modes – normal operation mode or program mode. There is a “jumper” on the modem PCB that looks like two gold pins that sticks up from the board, about 2mm apart, that determines whether the modem should start up for normal operation or be ready to have its memory chip flashed.

If we flip the modem over, we’ll see that there are two rubber feet towards the rear of the modem. Use sharp fingernails or a small flat screwdriver to gently remove them. There is no adhesive that sticks the rubber feet onto the modem.

After removing the two rubber feet, the silver metal screw will be exposed. Remove the two screws.

At this point, the base plate is ready to be removed. Pivoting on the front of the modem, gently lift the rear part and remove the base plate.

Then, remove the green PCB from the top case, flip it over and let’s see what we have:

Not very interesting.. to me at least. Perhaps someone can make sense out of all the bits on the PCB. However, just looking at it, you can identify the Realtek network chip, probably a network switch controller. To top left, you’ll see some I/O pins, not sure what they’re for. Just next to that, labelled “NetComm V6.1021.2SD” is the Intel flash memory that we’re going to write onto. Further right, that’s the Conexant modem controller.

See that big black package just above the silver hub of LAN ports? It’s actually just a transformer, as indicated by the symbol. It’s nothing really too spectacular there, other than its being rather large compared to the other bits.

Now let’s find the jumper that allows us to put the modem into program mode.

Plug in a jumper connector, or anything that can short circuit those pins. If you’re good, you can just twist a paper clip into a suitable shape.

Now that we’ve set the modem to start up in program mode, we’re ready to connect that to the computer. Connect the power cable, USB cable and ethernet cable. Connect the other end of the USB and ethernet cable to the computer you’ll be using to flash.

Now we’re ready to boot up our PC.

Starting the computer

The computer I used was an old Intel Celeron 1.3GHz, running on an Intel 8xx series chipset. I’ve connected the USB to one of the ports at the back of the computer, and ethernet cable on the onboard LAN.

Set your computer to boot from floppy, either via BIOS settings, or startup boot menu. Boot from floppy disk.

This will start up similar to your regular Win98 disk (if you’ve used that before).

But instead of giving you a command prompt, it’ll take you to the modem flashing utility.

The prompt will ask you for the speed of your computer. The reason for this is, a fast computer will need to be manually slowed down so that you don’t send the firmware data faster than what the modem is capable of receiving.

So I’ve selected option 2, meaning that my computer is faster than 500MHz, and needs to be slowed down. Then it’ll go ahead and get the computer ready for flashing.

Now just follow the instructions. We’ve already done the jumper step, so all we need to do is turn the modem on, and then press a key.

The program will then proceed to detect the modem. If it can’t find the modem, try switching the modem on. If it is switched on, then you might need to try another USB port. I’ve found that it helps to remove all other USB devices from the computer, since the software has the tendency to look at the first USB device and decide that it is not a modem that it can flash. You really don’t want to accidentally erase your other USB devices. (Even though it can’t.)

It’ll go ahead and erase the existing firmware, and put the new one on.

If all goes well, then it’ll tell you that flash was erased successfully. Now we need to supply the MAC address of the NetComm modem. For the first one, use the modem’s MAC address, which should be written on the modem’s base plate.

For the second one, just use the same MAC address, with the last 3 octets as FF’s. The recommended address given should be correct. Hit enter, and the software should be able to find the modem through the ethernet connection, and start uploading the new firmware onto it.

Again, if all goes well, then it’ll tell you to be happy. Otherwise, repeat the entire process and play around with your setup. Feel free to ask me for advice if yours isn’t working.

So that’s how I got the NetComm NB1300 plus 4 back into working order. I hope this works for you as well.

Related files:

Since a few people has had a bit of trouble finding these files, I’ve made them available below. I’ve put the RAR inside a ZIP to keep WordPress happy. Enjoy!

• NB1300_DIY_REPAIR.zip (6.12MB, contains NB1300_DIY_REPAIR.rar)
• NB1300_V6.1021.2_FTP_Upgrade_Unix.zip (1.60MB)