Hi,

I have recently acquired a tenda 3G150B device, and after some playing (very short really) I've managed to turn it into a brick.. really easy.

Here's the inside overview:
3G150B 150Mbps Portable 3G wireless Router

My questions to the experts:
-Would I be able to recover this brick with a re-flash?
-Would I be able to reflash with OpenWrt

Due to tenda's great support, they preferred to return the money.

Thanks

J2 might be a serial port, so there might be a chance to get more information on whats wrong and to flash a valid firmware.

Hi, thank you for your feedback.

Thought about that and based on the power voltage tried to connect a UART adapter to it, without success.

It's clear that something is being output through that J2, from left to right for each pin: 3,3v constant - 0v constant - 3,3v varying - ground

J2 Serial port: Connecting to a UART TTL 3,3v:
VCC - RX - TX - [GND]

Many Thanks!

Edited: Serial Pinout

(Last edited by gsmart on 14 May 2012, 10:29)

0v constant should be the routers rx, 3,3v varying its tx. Also make sure to use 3,3v levels when connecting to the router, so no direct connection to pc serial ports!

Hi All,

Got it! Managed to connect the UART TTL 3,3v to J2 Serial and recovered my box.

Attached serial output.

Serial output

Just remember, my root problem was a wrong firmware upgrade, now I got access to the serial and managed to load the correct firmware through U-Boot.

Thanks!

Edited: Replaced unanswered questions with answers.

(Last edited by gsmart on 14 May 2012, 10:16)

i have done this scenario. what should i do?

i tried to edit its settings in the server page, but accidentally installed wrong firmware of 3G150M in my router. Now my router is not working. I tried to go back to server page to revert back to original firmware, but its not opening. I am stuck now. Can you tell me how I can reset 3G150B router to its default settings. I pushed the Reset button present in router, but its of no use, as wrong firmware cannot be resetted like this. All lights are showing up so its only firmware problem.

just do serial recovery, like gsmart did.

how to do serial recovery? please guide me on doing it on windows xp?

search the wiki for terms like "serial", "debrick" and "tftp" and read the articles.
Serial pinout is mentioned there.
This logfile provides all the steps necessary to recover the device.

any tutorial please or i will have to pay 70 dollars for it to service center!

the wiki and this thread provides sufficient information, no need for another tutorial. you either put some effort in informing yourself, or you will have to pay someone else for it.

Hi arizshah,

you must have some base knowledge before trying this. This operation will void the warranty.

Material:
Philips and slotted screwdrivers to open the box
Solder iron
Some 0,5 wire
USB Serial 3,3v Adapter

Free software:
Putty and TFTPD32

Steps:
-Open the box (http://goo.gl/pZHSp)
-Solder the J2 pads, according to the provided pinout RX - TX - [GND], only these are needed.
-Connect the serial adapter to the wires
-Connect putty to the serial adapter COM port
-Boot the router and follow the same procedure as the provided in previous post, stopping the boot process and proceeding with the firmware download from tftpd32 server.
-Reboot it
-Clear the solder and close the box.
-You're done

Like said, this operation requires some time and knowledge, If you've never done this kind of things it may take a while and you'll be on your own..

Good luck!

-Solder the J2 pads, according to the provided pinout RX - TX - [GND], only these are needed.

where are these J2 Pads? i dont get them please mention it.

J2 is to the right of the Rallink chip in the picture linked above:
https://www.dropbox.com/s/hb87nue3r3i4l … 012753.jpg

bro how to get flash file for the device?

http://www.tenda.cn/tendacn/DownLoads/s … ductid=391

robthebrew bro

bro if u have full detail could you send it to me as i don't know how to insert this flash file into bricked device or do all the steps. i m noob into all this.

proceeding with the firmware download from tftpd32 server.

that portion???

Hello everyone

I need your help. I'm desperate. I have little idea, but I want to try the solution you have this same problem I have.

I ask you, please, help and a little patience with me.

Indeed, I saw the J2 pads to the right of Rallink chip.
But I understand that there are four solder points:

From left to right: □ ○○○ (Square - Round - Round - Round)

On the other hand, I have the USB cable where I can specify that:
- Red wire (VCC 5v / 3.3v)
- Wire Black (GND)
- White Cable (TX)
- Wire Verde (RX)

What exactly the order they would to solder?

Could it be ...

      - Square: NOTHING
      - Round 1: Green
      - Round 2: White
      - 3 Round: Black ???

What do I do with the red wire?

I do not understand the next step indicated:

"-Connect the serial adapter to the wires"
"-Connect putty to the serial adapter COM port"

Would I could explain?

thank you very much

Transmit from your adapter (white wire) goes to receive on the router (first round pad) and vice versa.  So it would be (red) white green black.  In most cases you do not need to hook up the red wire, but if you find you are receiving data from the router but can't type to it, go ahead and hook up the red wire to the +3.3v pin (square pad).

If you have a windows computer, download and install the program "putty" and plug in your USB adapter then configure putty to use the adapter's COM port which is usually COM3.  For most U-boot devices the baud rate is 57600 but if you receive garbled data try 115200.

Thank you very much for the help you are giving me.

Now I soldered the wires to the board router as I said MK24 friend. What was introduced to a USB port and the lights came on !!

http://www.subirimagenes.net/i/150412035717872219.jpg

I installed the "putty" program, but seems to work well.
I pass the image to see what I'm inserting values.

http://www.subirimagenes.net/i/150412035306324295.jpg

A beep ago, but I do not know if it is correct or not.

In the tftpd32 program would have to leave the router in the combobox?

http://www.subirimagenes.net/i/150412035309531632.jpg

What am I doing wrong?

Thanks for you help

Are you using a USB-serial adapter or just a raw USB cable?  Your cable must have a board with a chip between the USB plug and the wires you connect to the router.  You cannot connect the USB port directly to the pads on the router, it will not work and is likely to cause hardware damage.

You don't have to worry about running tftp until after you are able to control the router by typing commands in putty.  Since that is how the process works, you use putty to command the router to make a tftp transfer.

(Last edited by mk24 on 13 Apr 2015, 03:26)

MK24 thank you very much for your help.

Indeed, the cable I have been using a simple USB cable. Now I'll check that you have not damaged the motherboard of the router. But I have seen that there are several models of USB-serial adapter. All serve or have to use some special?

Thank you very much again.
regards