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WirelessRudy
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Chock treatment..., life saver.....

Fri Apr 08, 2016 6:00 pm

Client with a SEXTANT had no more internet, antenna was not connected to AP.
Send technician; antenna was dead. Nor with power adapter, nor pocket 18V batter unit would start.... bad news.. :(

In the office prepared new one and told tech to bring in the old one.
First thing we always do is check if failing unit indeed fails, so we connect to our workbench setup....

BANG! a big spark and some smoke from the ethernet connector when the ethernet plug with poe (24V) was connected.
Well, that unit must be dead....... eeehhhhh, board boots up...? Checked PC, winbox loader... yes board is running!
Logged in, checked everything... all systems running! :?

Disconnect unit since two more times, two more time no more light effects, normal boot procedure, running fine.... how weird..

Gave board closer look, some spider rags around... but no dead or cremated spider.... so what happened we don't know, but the unit is back reday for production! A real chock treatment! :D
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Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
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pukkita
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Re: Chock treatment..., life saver.....

Fri Apr 08, 2016 8:43 pm

electrotherapy! :D
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docmarius
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Re: Chock treatment..., life saver.....

Sat Apr 09, 2016 5:19 pm

Probably a short (possible a decoupling capacitor or a foreign object) on a power supply line.

As long as it could not draw enough power, the short circuit did hold. Once you powered it up with enough "juice", the part blew and the short was resolved. Check for small, rectangular, once yellow-brown, now black, parts on the PCB, with a small smoke halo.
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pe1chl
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Re: Chock treatment..., life saver.....

Sat Apr 09, 2016 7:32 pm

so what happened we don't know, but the unit is back reday for production!
I am happy I am not your customer!
 
WirelessRudy
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Re: Chock treatment..., life saver.....

Mon Apr 11, 2016 2:04 am

so what happened we don't know, but the unit is back reday for production!
I am happy I am not your customer!
And why is that? This unit is now working normally for 3 days in a test site and works fine. I see no defects...
If I had to ditch everything that sometimes shows some weird symptoms or effects I would have a container full by now of units that sometimes still could work for years.....
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Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
pe1chl
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Re: Chock treatment..., life saver.....

Mon Apr 11, 2016 10:24 am

For experiments, yes. But in a production environment for a paying customer? No.
At least I would have the thing investigated by someone who can say more than "what happened we don't know".
Failures like this are more likely to be caused by an exploding capacitor than by a dead bug that is now out of the way.
And also, the remaining charred material will probably present a low-resistant path, if not now then in the future
when it gets moist.

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