RB750G Suddenly Dead

RouterOS General
1

Hi guys,

My RB750G was ok, but suddenly all LAN disconnected, only power LED is on.

Then I tried to unplug the power then plugging it back in but still no luck.

I also tried to press the reset button for 10 seconds (hoping for a system reset) but no luck either.

Any clue what’s wrong with my RB750G and what am I supposed to do with it?

FYI: RB750G doesn’t have any console port.

2

bump

3

Try other power adapter.

4

Open it up and look for bad/bulging capacitors.

– Nathan

5

My routerboard also went down (no power led).
It hapened 3 times in a week, after 5-6 years without powering down.!

I’ve opened it, and these are my capacitors..
router_capacitors.JPG
Maybe related with http://forum.mikrotik.com/t/bad-capacitors-on-rb1000/62101/1
In this post, chojrak11 tells:

I had some of those, too… It’s a real plague in the industry. > https://en.wikipedia.org/wiki/Capacitor_plague

I’ll try to replace them… Any advice from someone?

6

Just replace them. No other advice.

7

Thanks, but I meant on the replacement type/characteristics … of the new capacitor

8

Use the same capacity / voltage values like you see on the capacitors. It could be slightly bigger if you cannot get the same.

9

I put behind of it’s dead though.. My RB750G has been working perfect for me for a very long time.

But the problem is I haven’t downloaded the configuration backup :frowning:

Unfortunately it doesn’t even have a serial port.

10

TRY THE 30-30-30 RULE METHOD. (FROM GOOGLE SEARCH)

  1. when the unit is powered on, hold down its reset button for 30 seconds
  2. while still holding down the reset button, unplug the router from power and hold for an additional 30 seconds
  3. still holding down the reset button, turn on power to the router again and hold for 30 more seconds

After this process (a total of 90 seconds) is complete, your router should be restored to its factory default state. Note that your particular router may not require the full 30-30-30 procedure. For example, some routers can at times be hard reset after only 10 seconds and without power cycling. Nevertheless, I still recommended memorizing this 30-30-30 rule as a general guideline.

11

Even though it doesn’t make any sense, but cool man, I will try once I get home and will update you guys if anything happens :smiley:

12

There is no such thing as “30-30-30 RULE METHOD” for RouterBoards. What you should try is this:

  1. Press reset button, power on the device and immidiately release the reset button. This will hopefully start the router with backup bios. If it boots up, you should upgrade your firmware.
  2. If the above procedure does not do anything, try to reinstall the router with netinstall. Press and hold reset button, power on the router. Does the ACT led start to blink after holding the button for a few seconds? If it does not, it is probably a hardware failure, if it blinks, do a fresh install with netinstall. If you can not get an ethernet link during netinstall, it is most definitely ethernet hardware problem.
13

I had the same problem and replaced the condensators and my 750 is running perfectly again for more months now. The way that the condenstors looked at your picture I would say that you will not get it going again without replacing them. But it is easy done. I used 820uf 6.3V. and bought some extra :slight_smile: for my other units.

rgs

14

Hi emils,

I tried, but nothing happened (all eth ports are still inactive)

Only PWR Led is on.

15

Did you try the 30 rule? It work for me. Just keep on trying at least 3 times. Here is more info.:
Hard Reset (“30/30/30 reset”)

Holding down the reset-button while plugging in the router achieves a different goal than the thirty second reset. Here the bootloader is in charge, so getting it to clear the memory for you may have different results. Some platforms will completely empty the nvram and depend on another stage of the bootloader or firmware to repopulate it. On some less-supported hardware this may have unpleasant results, so use the following two reset methods cautiously.

How to do a “30/30/30 reset”

To do a “hard reset for anyone not knowing OP or otherwise, hold the reset button with the power on, for 30 seconds, then while continuing to hold the reset button, unplug the router, continuing to hold the red button in the back for 30 seconds, and while still holding it in, plug in the power again and keep holding the reset button for an additional 30 seconds. This will wipe the nvram out. Keep in mind with hard resets the routers can be touchy I had to do it three times till it fully cleared out the nvram on mine” I think this forum poster actually meant that it will reset back to firmware/factory defaults, but as stated above, it could have unpleasant results “on some less-supported hardware”.

16

The idea with capacitors might be right. They are getting bad time to time.