MikroTik RB450G, Руководство по устранению неисправностей

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RB doesn’t boot, green and blue LED’s is shine
The board is unrepairable
Change faulty crystal oscillator
NO 40MHz
Problem
still appears
Change faulty ferrite beads
Check 2.5V output,
for example on C849 pins
Check CPU core 1.2V output,
for example on C853
Check 40MHz clock on crystal
oscillator Y301 pin#3
Check ferrite beads FB801, FB806
resistance. It should be less than 1 Ohm
Change faulty DC-DC Step-Down
converter U805
O
K
NO 2.5V NOT OK
Check ferrite beads FB802, FB803
resistance. It should be less than 1 Ohm
NO 1.2V
Change faulty DC-DC Step-Down
converter U806
OK
Try to change RAM memory
U201-U204
PoE does not work
Change faulty diode bridges
Check diode bridges
D805, D806
O
K
NOT OK
Change faulty connector
Check connector
J504
NOT OK
The board is unrepairable
Problem
still appears
Change faulty ferrite beads
NOT OK
O
K
O
K
O
K
Try to change processor
U1
O
K
Change faulty ferrite beads
Check ferrite beads FB701, FB702 resistance.
It should be less than 1 Ohm
O
K
N
O
T
O
K
NOT OK
Change faulty ferrite beads