Repairing a ubiquiti edgeswitch, need help

[asgard20032]

Symptom : not working, led not light up, but fan spinning...


First, I confirmed that the power supply is working. After, from the label on the pcb, i was able to identify some critical voltage : 3.3, 5, 1, 1.5... and confirmed they where all working. One voltage did not match the label : 12V (there was 6v there). I tried to find which chip would regulate that voltage. Unfortunately, by probing the chip, my multimeter probe did a bridge between 2 pin the the chip, and i heard a spark, then no voltage is right anymore.

Can someone help me find the datasheet?

It is the chip labelled VR1. I am pretty sure it is a voltage regulator with a name like that. There is a 24V comming inside (from the powersupply unit.)

[Monkeh]

AOZ1212.

[asgard20032]

Fortunately, i shorted the pin 7 and 8, so it must be repairable... only that chip should be damage, since it mean i shorted the Vin (24 volt) with the vbias pin (this pin is only connected with a cap to ground). Thus, i just fried that chip... at least, thats my guess, until i see other thing not working.

[Old Don]

If it was reading 6volts prior to your probe damage then something was drawing too much power pulling down the output. So I'd supply 12V from a current limited power supply and see what gets hot before repairing the regulator chip.

[asgard20032]

Define low current... this regulator is suppose to power up the whole thing, including a broadcom IC and a custom IC that does all the processing. Since I don't know the spec of that ASIC, I cannot just guess them and say that it should not draw more than 200 mA for example... this ASIC has an internal CPU for sure, running a linux (edgeOS, a derivate of VayOS or something like that, that is a linux), and a whole hardware accelerator for swtich, vlan and other thing).