How To: Erasing the effects of pin 9 short

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PUNiZZLE
DD-WRT User


Joined: 06 Apr 2008
Posts: 79

PostPosted: Mon Jul 13, 2009 20:20    Post subject: How To: Erasing the effects of pin 9 short Reply with quote
If you have ever used the method of shorting pin 9 on the Asus WL-500W or Asus WL500gP to recover your "bricked" router you have done hidden damage in the process of recovering it.

Pin shorting thread (http://www.dd-wrt.com/phpBB2/viewtopic.php?t=25070)

To remove the effects of pin 9 short:
1) Telnet/SSH into your router
2) Run the following commands:
Code:
erase /dev/mtd/3
erase /dev/mtd/4
reboot



This will erase the effect of pin 9. The pin 9 short has been known to cause various issues.

NOTE: This will reset your firmware to factory defaults.

This will not erase any hardware damage done by pin 9. Only the "software" damage.

Credit to Oleg. I can't remember where or when I found this, I just know he was the one to post it.

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I'll short all the pins on my router before I ever build a JTAG. Twisted Evil
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tzoom84
DD-WRT Novice


Joined: 18 Nov 2009
Posts: 8

PostPosted: Thu Nov 19, 2009 17:08    Post subject: Reply with quote
Uh oh,

I just did a pin-9 short last night as a last resort on a fairly new WL-500W. What kind of hardware issues can I expect to have?

From the originating pin-9 thread, it seemed to be successfully for many. Can I expect to have GUARANTEED hardware damage from this? Or just a likelihood?
redhawk0
DD-WRT Guru


Joined: 04 Jan 2007
Posts: 10909
Location: Wherever the wind blows- North America

PostPosted: Thu Nov 19, 2009 18:18    Post subject: Reply with quote
tzoom84 wrote:
Uh oh,

I just did a pin-9 short last night as a last resort on a fairly new WL-500W. What kind of hardware issues can I expect to have?

From the originating pin-9 thread, it seemed to be successfully for many. Can I expect to have GUARANTEED hardware damage from this? Or just a likelihood?


Just likely....I have a 500W that was donated to me and it was pin shorted...my unit flashes and runs fine as long as power isn't disconnected for longer than 3-5 minutes...if the power is disconnected longer than this....the unit reverts to default dd-wrt settings and a reconfig needs to be done (I used restore when it happens to me)

I'm sure there are other HW problems associated with pin shorting...but this is my experience.

redhawk

_________________
I currently test dd-wrt on Asus, Buffalo, Linksys, and Netgear. Too many to list.

Looking for more test units (newer models) for the project...got a brick?...PM me to make a donation. (USA) A donation is not a debricking service....it is a way to "Give back" to the dd-wrt project.

I do NOT provide personal assistance through chat or phone....so please don't ask.
tzoom84
DD-WRT Novice


Joined: 18 Nov 2009
Posts: 8

PostPosted: Thu Nov 19, 2009 19:08    Post subject: Reply with quote
Sounds like the shorting turned your NVRAM to just plain VRAM Smile.

I'll keep an eye out for quirky things. I still don't quite understand how shorting a data/address pin (pin 9) erases the nvram but I guess it is what it is ... And it is something I should always now avoid Smile
redhawk0
DD-WRT Guru


Joined: 04 Jan 2007
Posts: 10909
Location: Wherever the wind blows- North America

PostPosted: Fri Nov 20, 2009 18:39    Post subject: Reply with quote
Update on this.

As stated above my 500W unit would loose its configuration and revert to default dd-wrt values if I left the unit unplugged for 5 minutes or longer.

So...today I tried the

erase /dev/mtd/3
erase /dev/mtd/4
reboot

set of commands on it...it reboots itself...configures, then looses its config again after being unplugged for 5 minutes.

So...I thought, maybe it is comething in the FW partition causing my problem.

I decided to start from bare cfe only.

erase /dev/mtd/3
erase /dev/mtd/4
mtd unlock linux
mtd erase linux

Now I power cycled it and tftp'd the firmware to it again (mini_asus.trx)

After it booted up, set the new dd-wrt password, went to the Admin tab and reloaded 13230 NEWD big file.

Now reconfigured from scratch....and tested unit...working normal...unplugged for 30 minutes, plugged it back in...and all was well.

so it appears that in my case something in the linux partition was causing the unit to reset it's nvram section when power was disconnected for a length of time. I may never know what caused this...only that this process cured it.

redhawk

_________________
I currently test dd-wrt on Asus, Buffalo, Linksys, and Netgear. Too many to list.

Looking for more test units (newer models) for the project...got a brick?...PM me to make a donation. (USA) A donation is not a debricking service....it is a way to "Give back" to the dd-wrt project.

I do NOT provide personal assistance through chat or phone....so please don't ask.
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