Ubiquiti Unifi U6 Lite Access Point POE power issue

[Clarify4082]

Hi,

I bought a Unifi access point for cheap which has no power when connected to POE.

If I insert 5V manually, the AP is starting and I can connect via the unifi app.

When connected to POE the board is dead .

There is a damage and a missing component/capacitor? [C8329], but I´m not sure if this is POE related:


I already replaced the poe-controller (LM5071MT-80) but nothing changed.
Need help to understand the POE input-circuit...

[CapLeaker]

Trace pin 1 on the LM5071MT backwards to the jack.

[Clarify4082]

Okay, will test.

In the meantime I checked the AP with an ubiquity POE-Injector and it worked perfectly
I suspect some handshake problem between the AP and my POE-switch...

I only get 17.7 V on pin 1 when connected to the poe switch...

[CapLeaker]

Get a different POE switch and try again. it should negotiate to 48VDC. If you just put 24VDC in as an example, the U6 lite. Wont work. Pin 1 can do up to 80VDC! Only seeing 17.7 VDC sounds wrong to me.

[Clarify4082]

Hi, thank you.

You´re right, the issue isn´t the access point, it is the POE-switch (Allied Telesis AT-GS950/10PS).

There´s a burnt chip on the power-supply board. Unfortunately I can´t identify this chip