RB750 hardware failure

Hardware MikroTik hardware general
1

3 months ago I setup my new RB750 Router and today i encountered a hardware failure on him. After i noticed that network is not working and i can’t connect to the router with Winbox the next step was to verify the router himself. The router was OFF, like there is no power supply on him. I unplug the Power adapter and plug in again but only a very short blink off all leds and then all dark again. Tried couple of times to unplug and plug again but the result was the same. I checked the Power supply with multimeter but it looks ok, 12V output. I took the Routerboard PCB out of the case and tried again the PowerUp procedure. After a couple tries i noticed a very very thin line of smoke. It looks like was coming from U2. Looking carefully in that area i noticed a 3V3 Test point but testing with multimeter there are no 3V3 present on the board. The U2 gets input of 12V on pin2 but there is no 3V3 output on the board.

Can anybody help me to fix this problem? It’s clearly a hardware fault but it strange to me to occur on a brand new RB750 and powered through UPS. Is maybe this a common fault to this model?

I made a search on the internet and noticed that there are many PCB versions of RB750 with different component casing and placement on the PCB. I attach the picture of my router PCB version (sorry for the quality of the photo):

Resurrect old RB750 v4.13 Mikrotik RouterBOARD
2

Once the components have released their magic smoke, there is no option but to return the board to your supplier (assuming it’s under warranty) or throw it away.

3

Or repair it by replacing the faulty components, assuming you are able to work on SMDs… At least one can try and throw it away afterwards :laughing:

4

da89ni, This is issue of the power regulator as you’ve mentioned, the IC might’ve malfunctioned and the small blink of lights that you see might just indicate the voltage regulator turns on but can’t perform. Anyways, if you have considerable soldering skills you can simply take the IC off and replace it with a new one. Most of the time when a voltage regulator malfunctions, it creates some other problems in the board as well. Best of luck though.

5

It is not that hard to remove. Just use a hot soldering iron & solder wick & a suction device.
When re-installing, use lots of solder flux.

6

Finally i received one iC LSP5502 and replaced the faulty one. After the power up i was forced to do a reset because i was unable to access the router but after the reset and backup restore the router is working fine. It seems that only iC LSP5502 was the problem.