MikroTik RB450G Operating instructions

TroubleShooting for RB450G
No power, blue LED doesn’t shine
Change faulty MOSFET
Check P-channel MOSFET
Q801
Check Zener diode
803
N T K
K K
The board is unrepairable
Problem
still appears
Check Schottky diode
802
Change faulty Schottky diode
N T K
K
Check resistor R819 resistance.
It should be 10 Ohm
Change faulty resistor
N T K
Change faulty components
N T K
Check PWM controller
U803 Change faulty controller
N T K
These repair instructions are for N N WARRANTY repairs only!
Please make visual inspection for signs of corrosion
or mechanical damages before starting.
Check PNP transistor Q802
and Zener diode 804
N T K
Change faulty MOSFET
Check N-channel ual MOSFET
Q806
N T K
KK

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 C U 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
OK
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
OK
NOT OK
Change faulty connector
Check connector
J504
NOT OK
The board is unrepairable
Problem
still appears
Change faulty ferrite beads
NOT OK
OK
OKOK
Try to change processor
U1
OK
Change faulty ferrite beads
Check ferrite beads FB701, FB702 resistance.
It should be less than 1 Ohm
OK
NOT OK
NOT OK
Change faulty ferrite beads

Ethernet port1 (J504) does not work,
drop ping packets
The board is unrepairable
Problem
still appears
Check 1.0V output,
for example on C619
NO 1.0V
Change faulty transistor Change faulty ferrite beads
Check voltage drop between diode arrays D507, D508
pin#1 and Ground. This value should be in the range from
0.21V to 0.26V measured in diode mode (hold “positive”
wire on the Ground and “COM” wire to D507 pin#1)
Change faulty diode arrays and
6-port GbE Switch U501
NOT OK
OK
Check 1.5V output,
for example on C841 pins
Change faulty ferrite beads
NO 1.5V
OK
Check ferrite bead FB501 resistance.
It should be less than 1 Ohm Change faulty ferrite bead
NOT OK
OK
Change faulty connector
Check transformer
TR501
NOT OK
OK
Check resistors R563-R566 resistance.
It should be 75 Ohm +/-1%
OK
Change faulty resistors
NOT OK
Check ferrite beads FB804, FB805
resistance. It should be less than 1 Ohm
NOT OK
OK
Change faulty DC-DC Step-Down
converter U807
Check N
transistor Q601
Check ferrite beads FB601,
FB602, FB604-FB607 resistance.
It should be less than 1 Ohm
Change faulty 6-port
GbE switch U501
Check 25MHz clock on
R541 pins
NOT OK
Change faulty Network processor
U1
OK OK
NOT OK
NOT OK
OK

Ethernet ports 2(J501), 3(J505), 4(J503), 5(J502)
do not work, drops ping packets
The board is unrepairable
Problem
still appears
Change faulty connectors
Check 1.0V output,
for example on C619
NO 1.0V
Change faulty transistor Change faulty ferrite beads
Check voltage drop between diode arrays D501-D506,
D509, D510 pin#1 and Ground. This value should be in the
range from 0.21V to 0.26V measured in diode mode (hold
“positive” wire on the Ground and “COM” wire to D501
pin#1)
Change faulty diode arrays and
6-port GbE Switch U501
NOT OK
OK
Check 1.5V output,
for example on C841 pins
Change faulty ferrite beads
NO 1.5V
OK
Check ferrite beads FB502-FB505 resistance.
It should be less than 1 Ohm Change faulty ferrite bead
NOT OK
OK
Check termination resistance between Tx
and Rx lines in the each Ethernet connector.
It should be 150 Ohm +/- 2%
NOT OK
OK
Check ferrite beads FB804, FB805
resistance. It should be less than 1 Ohm
NOT OK
OK
Change faulty DC-DC Step-Down
converter U807
Check N transistor
Q601
Check ferrite beads FB601,
FB602, FB604-FB607 resistance.
It should be less than 1 Ohm
Change faulty 6-port
GbE switch U501
Check 25MHz clock on
R541 pins
NOT OK
Change faulty Network processor
U1
OK OK
NOT OK NOT OK
OK

Reference
number
Part Number Manufacturer Description
J501-J503, J505 RB1-216BAK1A U.D. Electronic Corp. RJ45 10/100/1000 w/LED
w/Shield TD TH
Q802 BC856B,215 NXP Semiconductors Transistor PNP -65V -100mA
250mW Hfe=220-470 S T-23
D802 SX36-T3-LF Won-Top Electronics Co.,
Ltd.
Diode Schottky 60V 3A
SMA
FB501-FB505, FB601,
FB602, FB604-FB607,
FB701, FB702
D804
BLM15AG121SN1D Murata manufacturing Co. Ferrite Bead 120 hm 500mA
0402
BZX84B27-AU T/R 7" PanJit International Inc. Z-DI DE 0.41W 27V 2%
S T23
D501-D510 A Z8000CIL Alpha & mega IC TVS ARRAY L W-CAP
S T23-6
Q601 STD888T4
STMICR ELECTR NICS A. P
.
Transistor PNP -30V -5A 15W
Hfe=300 D-PAK
D803 BZX84C10-T1-LF Won-Top Electronics Co.,
Ltd.
Diode Zener BZX84C 10V 5%
225mW S T23
D805, D806 DB153S SINY RK C ., LTD. Diode bridge 200V 1.5A
DBS
FB803 WR06X000 PTL Walsin Technology Resistor 0R
0603
FB804, FB806 BLM18SG121TN1D Murata manufacturing Co. Ferrite Bead 120 hm 3A
0603
J504 8108-B114
Powerway Electronics Co.,
LTD
RJ45 w/LED w/Shield TD TH
w/oEMI TinPlated
Q801 A 4441 Alpha & mega Transistor M SFET P-Ch -60V -
4A 100m hm 3W S -8
Q806 AP9960GM Advanced Power
Electronics Corp.
Transistor M SFET N-Ch Dual
40V 7.8A 20m hm S -8
R563 - R566
CRCW060375R0FKTAB
C
Vishay Intertechnology,
Inc.
Resistor 75R 1%
0603
FB801, FB802, FB805 BLM18PG331SN1D Murata manufacturing Co. Ferrite Bead 330 hm 1.2A
0603
R819
CRCW040210R0FKTDB
C
Vishay Intertechnology,
Inc.
Resistor 10R 1%
0402
TR501 LCZ3N1ZB Cetus International Ltd. 10/100/1000 Single Ethernet
transformer SMD
U1 AR7161-BC1A Atheros Technology Ltd. 600MHz Network Processor
(LF-AR7100X chipset)
U201 – U204 NT5DS64M8CS-5T
Nanya Technology Europe
GmbH
DDR SDRAM 512Mbit DDR400
64Mx8bit TS PII-66
When you order components for repairing boards from our sales,
please, write components reference number not a part number
U501 AR8316-AK1E Atheros Technology Ltd. 6-port GbE Switch
U803 RT9206PS Richtek Technology
Corporation Power Controller S P-16
U805 - U807 RT8011APQW
Richtek Technology
Corporation
DC-DC Step down converter,
WDFN-8E
Y301
NA D40.000-C3C-CI4 NSK Jenjaan Quartek
Corporation
Crystal scillator 40MHz
30ppm 3.3V 15pF 0+70 7x5

RB450G Reference picture

RB450G Reference picture

RB450G Reference picture

RB450G utput Voltage picture