Going round in circles with RB493

RouterOS General
1

This is hopefully a very simple request, but I have lost a day on this so far with google, these forums and failed attempts.

I have an RB493 9 port switch which I haven’t used it for about 18 months, and yes I should not have binned the file with the password in it. But I did.

Now I need to use the switch again, but do not seem to be able to reset the unit to factory defaults.

  • I hold the reset button in on power cycle, wait till lights have finished flashing (as per RB750s I use) - No reset
  • I hold the reset button in on power cycle, wait till there is a single dulll beep - router neither reset or visible in WinBox, and returns to previous config on restart
  • I hold the reset button in on power cycle, and release as soon as it starts - router neither reset or visible in WinBox, and returns to previous config on restart

I have tried on all the ethernet ports AND the serial port to no avail. I am hoping “the big hammer” is not my tool of choice.

If anybody has the patience to explain what I am doing wrong, I would greatly appreciate it

Thanks in advance

2

Well, according to the manual ( :slight_smile: ), it’s different than the RB750s: the “reset” button you are depressing is not there to reset the configuration, but rather to allow you to use the backup bootloader, in case the main one gets clobbered somehow (page 8, “Primary Boot Loader”). To reset the configuration, you need to instead bridge the two sides of the “reset hole” with something like a piece of wire or paperclip or screwdriver head while you apply power (page 9, “Software Reset”). The diagrams on page 3 fail to point it out in this manual (an oversight, I’m sure), but it is on the diagram: it’s the two little half-circle things on the opposite side of the board from the serial port and power, at the back corner of the ethernet connector on the far side. One might mistake it for a screw hole at a glance. I believe you will want to keep the bridge in place until you hear the familiar “double-beep” signal that the router has finished booting.

Your serial port should work: just hook a serial cable up between it and your computer, set it to 115200 bps, 8 data bits, no parity bits, 1 stop bit, and no flow-control. You should see activity on it during boot-up and even be given a chance to interact with the bootloader (“press any key”, etc.).

Another way to wipe the configuration, if you don’t feel like opening up the case and bridging two parts of the PCB together, is to use the serial cable, but you can’t do it directly (there’s no “wipe configuration/reset to defaults” option that you would be presented with over the serial console). Instead, you would use the serial console to tell the bootloader to boot via PXE/ethernet instead of from the built-in flash, and then use the Netinstall utility to re-install RouterOS onto the board. Make sure to uncheck the box that says “Keep old configuration” if you want it to wipe all of the settings off – including the password – when it reinstalls the OS for you. The Netinstall page I linked to lays out the entire procedure for you.

– Nathan

3

Hard to believe, but I did read the manual first, but I clearly misunderstood. Probably reading what I was thinking rather than what was on screen.

Case opened, circle bits shorted, routerboard reset to defaults.

Many thanks for your patience and help, I think I deserved a bit (lot?) more sarcasm :smiley: