I have one RB750UP where the router itself works as expected, but the PoE and voltage monitor part went bad. The symptoms are all four red LEDs blinking (about 3 times per second), power applied to PoE out (with short pauses as the LEDs blink), and the voltage monitor doesn’t work (“/system health print” shows nothing). It happened shortly after I tried 5.19rc1 in the hope it would address the PoE out issues. Netinstall to 5.18, then upgrade to 5.19 (final) and firmware update from 2.39 to 2.41 didn’t change anything. Any idea how this device could be repaired, or am I stuck with using it as a regular RB750? Will 5.20 reflash the MCU with firmware that fixes the PoE issues, or can it only be reflashed if it’s already working? It depends whether you rely on the AVR bootloader to do self-programming, or just do the serial in-system-programming externally so even a totally blank MCU could be programmed, unless fuse bits are corrupted that need a parallel programmer to recover.
For a such a specific question, I will recommende you email support.
/Paetur
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OK, happy to report some improvement after upgrade from 5.19 to 5.20rc1 - it seems to have reflashed the MCU, at least the voltage monitor started working again, but there is still something odd with PoE output: poe-out=forced-on works as expected, poe-out=auto-on is the same as forced-on (enabled even without any load), and poe-out=off still gives this blinking (the power LED on the powered Bullet5 blinks the same as the red LED of that port on the RB). Tests done with the original 24V 2.5A power supply that the RB750UP came with. Will wait until 5.20 final to see if it fixes the device, or I will have to RMA it (or did upgrading to “rc” already void the warranty?).
no, software update did not void your warranty. In general, doing some soldering on the board will void warranty, unless there are changes for the router that are explicitly allowed and performed by professional.
OK, it seems 5.20 with PoE controller upgrade to 2.0 fixed my RB750UP blinking red (before upgrade, the firmware that was broken by 5.19rc1 was still reported as version 1.0). Thanks - more testing to follow later, hopefully the higher current limits will make things more stable at 12V DC (average load from UBNT radios set to a legal Tx power was much less than 500 mA, but I suspect very short current spikes triggering the over-sensitive protection).
first public release was named 2.0 to make difference what version exactly was in use, and make sure that previous ones do upgrade if required.
Now the limit on one port is 1A and total limit 2.2A.