The UBNT EdgeSwitch 24 250W and probably a number of other devices have a problem: the PoE+ negotiation is set to "on" by default, requiring a change to the 24V-passive mode in order to power some of their devices.
That's all fine and dandy, but the PoE+ "detection" signaling triggers the PoE "protection" circuit on some devices, like older UAP-AC-LITEs, among others. Once the PoE "protection" has been triggered, the device is *dead*.
So, you can set the PoE to "off" or to "24V-Passive" and plug in a device, but if you happen to perform a factory reset with any of those vulnerable devices plugged in, they will be *dead* by the time you figure out just what happened. Further, UBNT is now refusing to do anything about any devices that are out of warranty when their PoE switch murders them.
That's all fine and dandy, but the PoE+ "detection" signaling triggers the PoE "protection" circuit on some devices, like older UAP-AC-LITEs, among others. Once the PoE "protection" has been triggered, the device is *dead*.
So, you can set the PoE to "off" or to "24V-Passive" and plug in a device, but if you happen to perform a factory reset with any of those vulnerable devices plugged in, they will be *dead* by the time you figure out just what happened. Further, UBNT is now refusing to do anything about any devices that are out of warranty when their PoE switch murders them.
I accidentally killed an EdgeRouter-x by putting 48 volts on it. What I found is that there is a 24 volt Zener at the input that protects the device by going short circuit - then current-limiting from the power supply kills the voltage. This diode is not all that hard to replace and costs 64 cents. For my 24 volt device, the diode looks like this one:
https://www.digikey.com/product-detail/en/littelfuse-inc/SMCJ24A/SMCJ24ALFCT-ND/762606
I think you will find similar ones sprinkled throughout the ubnt stuff.
I haven't found a way to open the UAP-AC-LITE without damaging the shell, either. In theory, you can pry it apart and get the tabs disengaged, but the plastic at the thin edge starts deforming long before there's any give there.
I'm still boggled that the *default* state of the EdgeSwitch will damage other UBNT products, and they refuse to do anything about it.
just Google "uap-ac-lite disassembly" and you will find 4 articles on how to take it apart.
also - instead of the stock diode you could upgrade to 3 or 5 kW rating if it would fit
http://www.littelfuse.com/data/en/data_sheets/littelfuse_tvs-diodes_5.0smdj.pdf
The 1.5 kW rating of the standard diode should work if you have enough cable between the switch and the UAC (>100 feet I suppose)
This isn't something I use for AREDN. But the *switch* putting out enough voltage to fry another UBNT device in what's supposed to be a nonintrusive PoE detection is... troubling. Unless it's purely a design flaw in those two lines of APs, in which case I would have expected a recall or at least a warning, since I'm registered for the warranty on it.