Netgear CMD31T - any hope?

[neo_]

It does have a SPI chip, and like all SPI chips THEY ALL use the same wiring diagram. Simply use a USBJTAG NT and flash it like every other ForceWare modem. You DO NOT need any unique guide specifically for this modem.

Good point about that, they all do use a standard pin configuration depending on the package, ie, 8 pin or 16 pin. But if you're curious theinfiniti just find the flash ship on the board and google "partnumber datasheet" and read it, you'll find the pins there.

Every ForceWare modem has the same number of pins and pinout.

Here is a complete USBJTAG NT guide. Even though it is for another modem, the procedure is exactly the same.

How To Jtag Motorola SB6121 Modem With USBJTAGNT





The SB6121 uses a 16-pin SPI chip and the method is done the exact same way as the SB6120. There is plenty of information how to solder a SB6120 online. There is one “trick” I discovered which lead me to about 5 hours total (going mad) to dump the SPI when it should have only taken 30 minutes. To help others avoid this (as I’ve found in this forum and others) since there are people running into the same issue without an answer, I am writing this tutorial. This is mostly to help all the lazy individuals who cannot search hard enough. I also thought I'd share my method of soldering as I believe that if it is truly your testing modem it should be easily flashable. The test clip is cool but it requires you to disassemble the modem (every time) and is way too expensive now. I use a 8-9" 14 pin cable which can be bought at usbjtag website for an expensive $2.00. I like buying a IDC (2 x 7) 14pin ribbon cable (anywhere around 18”) on ebay or elsewhere for a whole lot cheaper in bundles of 10 or so. Once soldered you will never have to open up the modem again and can just flash with the external IDC connector. I am going to break this down to baby steps as this modem is cute and I believe all the new “testers” will buy this since it can commonly be found for $50.

**Before you continue you should test the modem and make sure everything is working as it should as you do have to cut the serial/mac sticker to disassemble**



Requirements

-Motorola SB6121 Modem
-Soldering Iron & Solder + soldering paste/flux
-T10 screwdriver + small flat head screwdriver (1.5)
-Wrench / Needle nose
-USB cable for external 5V
-USB JtagNT
-Electric tape
-Scissors and / or wire stripper
-Knife



Disassembly

1) Remove T10 screw above the ethernet & hexagon nut on the coaxial F-type connector
2) Cut the sticker
3) Depress 4 clips on the 2 top and 2 bottom of the modem ( use a small flat)
4) Remove PCB and flip over as the SPI chip is located in the back.



Prepare The Ribbon cable

1) cut the cable 8-9" long
2) strip and separate wires (you can cut the unused short to eliminate shorts & clutter)
**Use the RED cable for reference as it is easily identified as pin/wire number 1**
3) Wires 2 and 13 conductors should be twisted and tinned
4) use electric tape to wrap around the ribbon cable 2 inches from the IDC connector. (Used to protect cable and prevent stress on the solder joints)
5) Cut and seperate wires 14 & 13 near the IDC and
a)solder to your connector (here I used an old CD drive audio cable)
b)twist conductors to prevent fraying


Soldering

1) Tin the wire conductors using soldering paste then dip in paste and solder to corresponding pin. ( easiest way to a wire to the SPI joint is to come from on top and point downward so the wire and the pin are vertical.
2) Inspect all soldered joints
3) Place a piece of electric tape over the SPI chip.

5-Volt USB cable

1) Strip outer jacket to expose 4 wires and strip some of the commonly red and black coated wires (+ and GND)
2) twist or connect the + and - external power to modem.
** For the 5V source try to use either a PC jack or under 1 amp charger because of the low amps and not your 2 amp phone charger as I do not know how sensitive the chip is**

Confirm Soldering / SPI Access

1) Plug in USB 5V cable
2) connect DC jack on modem and let the modem boot (done waiting when the blue light is flashing "Receiving")
**Note: Sometimes the modem will boot with 2/3 dim LED's instead. Just wait 1 minute after providing power then proceed to #3**
3) while waiting go ahead and connect your USBJtagNT usb cable on both ends and start the software
4) set Category as Modem, Protocol to SPIFLASH and Target to SB6120
5) Connect USBJtagNT to ribbon cable (pay attention to pin 1 on the RED side)
6) set range to AllFlash and press ID to identify the chip
7) It should fail with FF,FF,FF
8) Unplug DC jack from modem (took me some time to find out)
9) ID the chip it should now be successful
**You can now reassemble the modem since the soldering was good**

Reassembly



1) Feed the 14 pin cable through the back plate's Ethernet port cutout.
2) Replace and hand tighten the F-type hexagon nut keeping the electric tape on the ribbon cable centered in between the shield and ethernet jack.
3) Reverse the disassembly process

Complete



Congrats you should now be good to go and never have to open up that modem again (unless you want serial). It was a pain figuring out that the modem needed power than it had to be removed in order for USBJtagNT to communicate with it.

****
Notes:
- You cannot use pin1 of USBJtag on pin 2 of SPI flash for Voltage, just not enough power.
- I know about the 5V on the NT, but I'd rather keep the insulator around the board, I'm sure many other new testers would.
- I will post the ISP point once I try it myself but soldering on the large SPI flash is easy and can save new solderers trouble.
- With this method I'm 110% sure this way would always work and would not have varying results.