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Help, accidentally connected 24v to a 12v ip camera and now it won't turn on.

Discussion in 'Power Electronics' started by Fedx, Nov 11, 2020.

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  1. Fedx

    Fedx

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    Nov 11, 2020
    Accidentally connected a 12v IP camera to a 24v poe port and I think I screw it because it won't trun on. Which components should I check first? Picture of PCB in the link attached. (Red is positive and green is gnd) thanks[​IMG]

    https://ibb.co/gTfJgyb
     
  2. Martaine2005

    Martaine2005

    2,968
    817
    May 12, 2015
    You should have no problem connecting a 24V device to 12V. It simply may not work and obvious polarity is a factor. Please tell us more.

    Martin
     
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  3. Fedx

    Fedx

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    Nov 11, 2020
    Hi, thanks for replying. The camera is a chinese 36x optical zoom 5 mp ip camera from ebay, its not natively POE supported but the seller told me to buy a POE splitter. I used the camera with its own 12v 4 amp adapter and a cat6 cable for 2 days without any problems but today i wanted to use the poe splitter so i connected everything and plugged my utp cable to my ubiquiti 150w switch, the problem is that the port was setup as 24v passive, after that when i connect the 12v adapter the camera wont turn on and the blue LED inside the adapter starts flashing. As soon as i disconnect the camera the LED stays on, i tried other devices with the adapter and its working fine. Thanks
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    10,591
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    Nov 17, 2011
    But he connected a 12 V camera to 24 V. If he's lucky, only a fuse has blown. But the flashing LED indicates that something else has happened. I guess there is a short circuit in the camera that leads to overcurrent which in turn makes the power supply LED go flashing.
    @Fedx : can you open the camera and look for obvious signs of destruction? Maybe take photos an upload them for inspection.
     
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  5. Fedx

    Fedx

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    Nov 11, 2020
    hello, i already took the camera apart but i don't see anything burned or damaged. I tried attaching the image in the first post but i guess it failed so i left a link to the image. I'm trying to reattach the image in this post. I desoldered the AMS117 regulator which btw there are 2 regulators one on top of the other (soldered to the same pads) but i keep getting the failure so i'm hopping that the only components fried are the diodes (i saw 2 M7 1 M3 and 1 that said MB or BM) i'm no electrical engineer so any help or tips would be greatly appreciated since i really like electronics:) i have a reflow station and a good soldering iron and a medium/advanced soldering skills so i would be able to pull out components and solder them back. Thanks!
     

    Attached Files:

  6. Harald Kapp

    Harald Kapp Moderator Moderator

    10,591
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    Nov 17, 2011
    No obvious signs of destruction visible.
    Start by checking the electrolytic capacitors. They are rated 16 V and may have been damaged by 24 V. Although they do not the show the typical signs of overload (blown up cases, leaking electrolyte).
    Remove all cables from the PCB except to power input to limit the possible sources of failure to this pcb.
     
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  7. Fedx

    Fedx

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    Nov 11, 2020
    Hi, i desoldered the first diode that is marked as "BM" the pcb slot is TVS1 and now when i connect the camera it turns on and the power supply is working fine now (solid blue led not flashing anymore as before) so i guess i need to replace it. Any tips on how to find the exact replacement? Thanks
     
  8. 73's de Edd

    73's de Edd

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    Aug 21, 2015
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  9. Fedx

    Fedx

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    Nov 11, 2020
    phew! I hope it was just that component because everything else seems to be working fine, i will try to get a replacement by any chance do you know which kind of devices mainly have those diodes in? I looked all around my arduinos, sensors and in a wireless router but couldn't find a similar diode hehehe
     
  10. 73's de Edd

    73's de Edd

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    Aug 21, 2015
    I don't think that you will be finding a "freebie" in any other "things" that you have laying around.
     
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