MikroTik RB800r2v5, Troubleshooting Manual

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No power, blue LED doesn’t shine
The board is unrepairable
Check D20, Q4
NOT OK
O
K
O
K
Problem still appears
TroubleShooting for RB800r2v5
PoE doesn’t work
Check bridge rectifiers D17, D21
NOT OK
Check Zener diode D19, D22 and 3V
under voltage detector U21
NOT OK
Check N-channel MOSFET Q7
NOT OK
Check N-channel MOSFET Q9, Q10
NOT OK
Check power controller U22
NOT OK
O
K
O
K
Change faulty D20, Q4
Change faulty MOSFET Q7
Change faulty MOSFET Q9,
Q10
Change faulty controller
U22
Change faulty D17, D21
Change faulty D19,D22,
U21
Check N-ch MOSFET Q5 Change faulty MOSFET Q5
O
K
NOT OK
The board is unrepairable
Problem still appears
Check resistor R273. It resistance
should be 10 Ohm.
NO 10 Ohm
Change faulty resistor R273
Change faulty Q6 Check NPN transistor Q6
O
K
O
K
NOT OK