Ubiquiti Edgeswitch 16 POE Repair!

In this one we repair this POE switch that won't boot when certain ports are connected.
CAUTION do not work on mains operated device unless you understand the risks and how to do so safely.
Tools I use -
Soldering
Quick 861DW hot air station
Duratech TS-1640 solder iron
Multimeter
RMM760D - can be found under many name badges
Microscope
Luzky Zoom 3.5 - 90x simul-focus single boom stand trinocular stereo microscope
Camera - Lucky Zoom HD 14MP
Oscilloscopes
Siglent SDS 1102CML 100MHz 2CH
Philips PM 3305 35MHz 2CH
Function generastor
FY6900 (many brand names)
Thermial imaging camera
FLIR ONE PRO on android
Bench supply
Powertech MP-3086 0-30V 3A
TL866II PLUS universal EEPROM programmer

[@abeleski]

Look at you fix this thing like a boss👌

[@zx8401ztv]

Well done you clever devil lol :-D

[@jasejj]

802.3at PoE is nominally 48v so there would be no issue running a PoE device without the control protocol - some PoE injectors are passive and there are thousands of them deployed in the field, due to a few differing standards that came in that weren't interoperable ( older Cisco wireless APs for example). Also a non-PoE device won't (or at least shouldn't) be affected by having 48v run though - this voltage is DC-filtered on ingress and the card should only ever see the data signal. The one issue with running passive PoE is that it, and earlier 802.3af wasn't compatible with gigabit ethernet, which uses all four pairs. You'll note that your phone only connected at 100Mbps when the port was dodgy.

[@TheDefpom]

60v rated on a 55v rail.... hmm thats a bit close, might be why they died.