Ethernet doesn’t work
Check termination resistance between Tx and
Rx lines in the each Ethernet connector J601,
J602, J603. It should be 150 Ohm +/-2%
Change faulty connectors
Check voltage drop between D601, D602 or
D603 pin#1 and Ground. This value should
be in the range from 0.4 – 0.5V measured
in diode mode (hold “positive” wire on the
ground and “COM” wire to D601 pin#1)
NOT OK
NOT OK
O
K
O
K
Change faulty Ethernet
Switch U601
Check ferrite beads FB602 (for J601),
FB604 (for J602), FB603 (for J603). It
resistance should be less than 1 Ohm
Change faulty ferrite beads
NOT OK
O
K
Check 1.8V output, for example, on
PNP transistor Q601 pins
No 1.8V
Check Q601 transistor
N
O
T
O
K
Change faulty Q601
OK
Change faulty U601
O
K
Check 25.000MHz clock on crystal
Y601
NO 25.000 MHz
Change faulty Y601
Problem still appears
The board is unrepairable
Summary of Contents for RB433r3
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