[Chugalug] [CHUGALUG] Hardware Bug Story

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[Chugalug] [CHUGALUG] Hardware Bug Story

willmwade
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So I had been having issues with my Linux laptop. Nice thin laptop. Works well with Linux. Long battery life. Currently running a version of Arch, but has had a few others.

Had developed one small issue. Occasionally, it would freeze. Sometimes just freeze, sometimes with the screen all messed up. I started checking everything. I checked the ram first off (always a prime cause of random issues), the ssd, the cpu, the graphics driver, switched distros, etc...

There was one other small and I thought unrelated issue. Sometimes the left side keyboard backlight would blink. Never was it connected to the halts however.

The issue started getting bad enough that I noticed that it only happened when I was moving the laptop (something that tends to happen with laptops.) I pulled the back off and cleaned up the inside. Same issue, but I thought perhaps I should try to see if I can cause the issue by pressing on different places on the keyboard.

After a few keys I pressed hard on the 'S' key. And instant feedback of a freeze.

So I pull the back and pull out the system board, looking for a bad ground, and what should I find? The ribbon power cable that goes to the left keyboard backlight is broken. Pull it out, so it cannot use the backlight, put it back together and it all works fine, even when hard pressing the 'S' key.

All along the issue was a shorting backlight power cable! Goes to show how small things can really cause unrelated issues.

This has been bug stories with Wil. Join us next time for the mystery of the Macbook Pro with random reboots, unless a Thunderbolt Ethernet adapter was plugged in (but not used)!

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Re: [Chugalug] [CHUGALUG] Hardware Bug Story

Stephen Kraus

*clears throat*.....

....it worked fine on my machine. *dodges angry developer debris*


On Sep 24, 2016 8:39 PM, "Wil Wade" <[hidden email]> wrote:
So I had been having issues with my Linux laptop. Nice thin laptop. Works well with Linux. Long battery life. Currently running a version of Arch, but has had a few others.

Had developed one small issue. Occasionally, it would freeze. Sometimes just freeze, sometimes with the screen all messed up. I started checking everything. I checked the ram first off (always a prime cause of random issues), the ssd, the cpu, the graphics driver, switched distros, etc...

There was one other small and I thought unrelated issue. Sometimes the left side keyboard backlight would blink. Never was it connected to the halts however.

The issue started getting bad enough that I noticed that it only happened when I was moving the laptop (something that tends to happen with laptops.) I pulled the back off and cleaned up the inside. Same issue, but I thought perhaps I should try to see if I can cause the issue by pressing on different places on the keyboard.

After a few keys I pressed hard on the 'S' key. And instant feedback of a freeze.

So I pull the back and pull out the system board, looking for a bad ground, and what should I find? The ribbon power cable that goes to the left keyboard backlight is broken. Pull it out, so it cannot use the backlight, put it back together and it all works fine, even when hard pressing the 'S' key.

All along the issue was a shorting backlight power cable! Goes to show how small things can really cause unrelated issues.

This has been bug stories with Wil. Join us next time for the mystery of the Macbook Pro with random reboots, unless a Thunderbolt Ethernet adapter was plugged in (but not used)!

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Re: [Chugalug] [CHUGALUG] Hardware Bug Story

Billy
In reply to this post by willmwade
There's a lurker in here that has worked at UTC for a long time. He used to have (probably still does) a framed Ethernet card on his wall. It brought down the whole network in mid-1990. It started spewing out Mac chatter, caused a broadcast storm that brought down everything.

I think he also had a bad patch cable that brought down a main server due to bad connectors.

Both things were difficult to track and served as reminders to check the simple things first.

--b

On Sep 24, 2016, at 8:29 PM, Wil Wade <[hidden email]> wrote:

So I had been having issues with my Linux laptop. Nice thin laptop. Works well with Linux. Long battery life. Currently running a version of Arch, but has had a few others.

Had developed one small issue. Occasionally, it would freeze. Sometimes just freeze, sometimes with the screen all messed up. I started checking everything. I checked the ram first off (always a prime cause of random issues), the ssd, the cpu, the graphics driver, switched distros, etc...

There was one other small and I thought unrelated issue. Sometimes the left side keyboard backlight would blink. Never was it connected to the halts however.

The issue started getting bad enough that I noticed that it only happened when I was moving the laptop (something that tends to happen with laptops.) I pulled the back off and cleaned up the inside. Same issue, but I thought perhaps I should try to see if I can cause the issue by pressing on different places on the keyboard.

After a few keys I pressed hard on the 'S' key. And instant feedback of a freeze.

So I pull the back and pull out the system board, looking for a bad ground, and what should I find? The ribbon power cable that goes to the left keyboard backlight is broken. Pull it out, so it cannot use the backlight, put it back together and it all works fine, even when hard pressing the 'S' key.

All along the issue was a shorting backlight power cable! Goes to show how small things can really cause unrelated issues.

This has been bug stories with Wil. Join us next time for the mystery of the Macbook Pro with random reboots, unless a Thunderbolt Ethernet adapter was plugged in (but not used)!
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Re: [Chugalug] [CHUGALUG] Hardware Bug Story

Dave Brockman
On 9/25/2016 3:11 PM, Billy wrote:
> There's a lurker in here that has worked at UTC for a long time. He used
> to have (probably still does) a framed Ethernet card on his wall. It
> brought down the whole network in mid-1990. It started spewing out Mac
> chatter, caused a broadcast storm that brought down everything.

Somewhere in my basement, I have two 3Com cards that have the same MAC
address.  I'm pretty sure I physically destroyed with extreme prejudice
the Netgear card that only put 8 bits of its MAC address on the wire.

> I think he also had a bad patch cable that brought down a main server
> due to bad connectors.
>
> Both things were difficult to track and served as reminders to check the
> simple things first.

Always, always, always try a different patch cable.  It's your first and
cheapest (in terms of labor and materials) troubleshooting option.  And
you may be surprised how often it actually changes things.

Regards,

dtb


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Re: [Chugalug] [CHUGALUG] Hardware Bug Story

Mike Harrison-4

> On Sep 25, 2016, at 4:48 PM, Dave Brockman <[hidden email]> wrote:
>
> On 9/25/2016 3:11 PM, Billy wrote:
>> There's a lurker in here that has worked at UTC for a long time. He used
>> to have (probably still does) a framed Ethernet card on his wall. It
>> brought down the whole network in mid-1990. It started spewing out Mac
>> chatter, caused a broadcast storm that brought down everything.
>
> Somewhere in my basement, I have two 3Com cards that have the same MAC
> address.  I'm pretty sure I physically destroyed with extreme prejudice
> the Netgear card that only put 8 bits of its MAC address on the wire.



Depressing:
Saw a batch of cheap (Realtek compatible generic, long time ago) cards once that seemed to only have a small number of Mac’s they rotated through. Had a bunch of dupes.

And a (name withheld due to NDA) WiFi router I have on my desk is one of many flashed with the same MAC address. We learned to edit a boot loader image with a hex editor and reload.
The vendor “Why would you have more than one?"

Worth knowing: Newer WiFi gear won’t let you (easily) reset the MAC for Wireless even with OpenWRT. Depending on the hardware, there are ways. The The FCC wants it more “secure”.

Had a house guest a few days ago that had a neat add-on: every time he rebooted, a script generated and set a new pseudo-random MAC.








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Re: [Chugalug] [CHUGALUG] Hardware Bug Story

Andrew Rodgers-2
@mike Windows 10 does this on every reconnect to wireless networks you deem "untrusted"

On Sun, Sep 25, 2016 at 5:56 PM Mike Harrison <[hidden email]> wrote:

> On Sep 25, 2016, at 4:48 PM, Dave Brockman <[hidden email]> wrote:
>
> On 9/25/2016 3:11 PM, Billy wrote:
>> There's a lurker in here that has worked at UTC for a long time. He used
>> to have (probably still does) a framed Ethernet card on his wall. It
>> brought down the whole network in mid-1990. It started spewing out Mac
>> chatter, caused a broadcast storm that brought down everything.
>
> Somewhere in my basement, I have two 3Com cards that have the same MAC
> address.  I'm pretty sure I physically destroyed with extreme prejudice
> the Netgear card that only put 8 bits of its MAC address on the wire.



Depressing:
Saw a batch of cheap (Realtek compatible generic, long time ago) cards once that seemed to only have a small number of Mac’s they rotated through. Had a bunch of dupes.

And a (name withheld due to NDA) WiFi router I have on my desk is one of many flashed with the same MAC address. We learned to edit a boot loader image with a hex editor and reload.
The vendor “Why would you have more than one?"

Worth knowing: Newer WiFi gear won’t let you (easily) reset the MAC for Wireless even with OpenWRT. Depending on the hardware, there are ways. The The FCC wants it more “secure”.

Had a house guest a few days ago that had a neat add-on: every time he rebooted, a script generated and set a new pseudo-random MAC.








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Re: [Chugalug] [CHUGALUG] Hardware Bug Story

Michael Scholten
We had a couple cheap android tablets do the same mac address dance. As I recall one was a Hisense brand. Can't remember if the other(s) was\were the same.

Also had a NIC nearly take down our network once when it decided to go belly up. Just started screaming on the network for an IP address but never acknowledged receiving one. Between it and the DHCP server flooding the network nothing else could really get through.

On Sun, Sep 25, 2016 at 6:24 PM Andrew Rodgers <[hidden email]> wrote:
@mike Windows 10 does this on every reconnect to wireless networks you deem "untrusted"

On Sun, Sep 25, 2016 at 5:56 PM Mike Harrison <[hidden email]> wrote:

> On Sep 25, 2016, at 4:48 PM, Dave Brockman <[hidden email]> wrote:
>
> On 9/25/2016 3:11 PM, Billy wrote:
>> There's a lurker in here that has worked at UTC for a long time. He used
>> to have (probably still does) a framed Ethernet card on his wall. It
>> brought down the whole network in mid-1990. It started spewing out Mac
>> chatter, caused a broadcast storm that brought down everything.
>
> Somewhere in my basement, I have two 3Com cards that have the same MAC
> address.  I'm pretty sure I physically destroyed with extreme prejudice
> the Netgear card that only put 8 bits of its MAC address on the wire.



Depressing:
Saw a batch of cheap (Realtek compatible generic, long time ago) cards once that seemed to only have a small number of Mac’s they rotated through. Had a bunch of dupes.

And a (name withheld due to NDA) WiFi router I have on my desk is one of many flashed with the same MAC address. We learned to edit a boot loader image with a hex editor and reload.
The vendor “Why would you have more than one?"

Worth knowing: Newer WiFi gear won’t let you (easily) reset the MAC for Wireless even with OpenWRT. Depending on the hardware, there are ways. The The FCC wants it more “secure”.

Had a house guest a few days ago that had a neat add-on: every time he rebooted, a script generated and set a new pseudo-random MAC.








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