Today my client returned me malfunction RB750G
Ether ports are not working.
Attached cable and LED of eth port is not become green. All 5 of them same symptoms.
Caps seems to be fine. They are flat.
what part could I replace to bring it back alive.
The money are not problem and I have plenty of RB’s but I really love RB750G.
Is there some chance to be repaired?
First step: hard reset.
What makes you think is a diode, if you also consider its color?
Sorry smd resistor.
Looks more like an SMD cap from here, but hard to see details on that image.
(And a cap failure in the power section can definitely take things down . . . )
It's capacitor but you have burned other components as well. if you look closely behind ether ports and lan transformer (left side of HEX text) there're others burned as well. Sign of lightning or improper voltage come from port. If you able to use some ports use it as is. Doesn't worth to fix it imho.
For testing purposes, try removing that capacitor and diode D1 as it seems its also burned.
That's probably a TVS diode, which is connected in parallel to power source and it's only job is to suppress voltage spikes. Capacitor probably failed shorted.
I would start here and work my way trough the circuit.
I had similar problem on my desk, 48V was fed to 24V antenna. Only TVS diode blew. After removing it device worked without a problem.
Can you take a photo of diode D1 so we can see it's part number ?
