Resurrect old RB750 v4.13 Mikrotik RouterBOARD

Hardware MikroTik hardware general
1

Hi all,

I try to resurrect an old RB750 found recently:
RB750-DIGI-WireShark.png
I performed hard reset on it, via RESET button, but nothing changed.
In WinBox it appears like this, with IP 0.0.0.0 :
RB750-DIGI-WinBox.png
I connect my PC to Port 2 and looked at WireShark messages:
RB750-DIGI.jpg
Any idea on what can I do in this case?
Is there a chance to resurrect it and use it like a normal router?

Or it is only good as a furniture? :slight_smile:

Thanks in advance.

2

Yikes !
4.13, that’s from … 2010 :open_mouth:

Using MAC address, user=amin, passwd=, doesn’t work ?

Since it shows uptime in Winbox, it is doing something and communicating.
Maybe Winbox 3.41 is too new for that thing ?
You don’t happen to have much older versions of Winbox around to try ?

But to be honest, apart form nostalgic reasons and toying around, I wouldn’t do anything anymore with such an oldie …

3

On the winbox screenshot, everything is set-up to click connect (when connect to is filled with MAC address, winnix will try to connect without using IP).

But there are a few problems:

  1. ROS version is extremely old, your winbox can’t connect to it due to change of how password is communicated. You’d have to use winbox version below 3.19 (or something like that)
  2. ROS version is extremely old, you shoukd install something way newer. But due to bullet #3 perhaps stay with ROS v6 (6.49.18). Due to extreme version difference you should upgrade in steps … AFAIK there was efen change in license format … and upgrading only slightly did convert license to new format. Quite posssibly directly installing a contemporary version wouldn’t do it properly.
  3. The device itself is ancient and relatively slow for todays standards. I don’t see any point in trying to use it, you may as well as invest into a hAP ax lite (list price $59) and start off with way more capable device. Unless you’re into making technical legacy alive …
4

Maybe you need an older (possibly very old) version of Winbox?

http://forum.mikrotik.com/t/where-can-i-get-old-winbox-versions/125278/1

5

I tried connecting on WinBox 3.41 with admin and no password, but unsuccessfully.

My main router is a hEX refresh E50UG, and my intention is to use this one as a playground and test bench to learn configuring Mikrotik routers.

RB750-DIGI-WinBox-3RC6.png
I downloaded old WinBox v3RC6, but when I try to connect I get WRONG PASSWORD.
RB750-DIGI-WinBox-2.2.18.png
RB750-DIGI-WinBox-2.2.18-error.png
With WinBox 2.2.18 I get this error when trying to connect.

It might be that this router in particular have customized firmware? DIGI is a Cable TV Company in Romania . . .

Thanks all for your suggestions.

6

3.0 RC6 Is from 2015, so maybe still too new?
Can you try to connect with v2.x via MAC? (of course It cannot connect via IP to 0.0.0.0)

7

So I tried connecting with WinBox 2.2.16 via MAC address, but I get WRONG PASSWORD if I lease password field empty.
Same WRONG PASSWORD I get when I try connect with WinBox 3.0 via MAC address.

I still think there is a custom firmware installed on it.
So won’t be a good idea to use netinstall to install the original ROS 4.13?

If so, I found here https://mikrotik.spectrumindo.com/mikrotik-routerboard-rb750-1.html that this RB750 will need MIPS-BE firmware, is that correct?

I also found a big repository of old ROS, WinBox, netinstall and other Mikrotik related files here: https://www.mikrotik-software.de/downloads/

8

I did try to use netinstall, but the router is not showing at all.

I configured my pc Network card to use:
IP Address: 192.168.88.2
Subnet Mask: 255.255.255.0
Defaul Gateway: 192.168.88.1
Prefered DNS: 192.168.88.1

On neinstall 4.13 I configured Net booting to 192.168.88.3

I disabled all other network adapters on PC.
Connect PC to PORT 1 of the router.
Powered off the router.
Holding RESET button, plugged in the power cord.
Continue to hold the reset button until router seams to restart.
Nothing shown on netinstall :frowning:

I am doing something wrong?
Any other idea I can try to resurrect this branded router?

Thanks!

9

Try one of the common credentials for digi, maybe - just maybe - they are the same:
https://19216811.uno/digi-router-login/
https://www.digi.com/support/knowledge-base/unique-default-passwords

10

I tried all combination possible, nothing works. :frowning:

Searching the internet I found that this router type was used as trail for DIGI IPTV in Romania.
I even contacted DIGI to ask for user manual, and they mention this device model is not present any more in their device portfolio . . .

11

Try again with netinstall.
Your settings seem correct, but there are reports that putting a (dumb) switch between the PC and the Routerboard can help in detecting the device (timing problems or whatever).
I would add that for such an old board I would try a 10/100 switch, just in case.

12

What I often do is to run wireshark … and I can see if/when device starts to communicate with netinstall binary on PC. Then and only then it’s time to let go the button.

13

I did what you suggested, but nothing happens. I uses a Gigabit switch (only one available) and also tried with a old TP-Link WR743ND V2 runing DD-WRT and configured without DHCP Server.

I follow your advice and opened Wireshark when powering on the router, nothing indicating that it is alive. :frowning:

Another info I’ve notice:

  • only PORT 1 and PORT 2 are giving me a MAC address, the other ports are not
  • the MAC address on PORT 1 is different then MAC address on PORT 2

So, in conclusion, am I the happy owner o a bricked router that can only be used as furniture? :slight_smile:

14

The Mac address of port1 different from that of port2 is normal, usually ether1 is WAN and the other ports are LAN (in a bridge), and it is entirely possible that ether3 and ether4 have been disabled, if the thingy was used to “convert” a connection to IPTV only, but that might mean that you did not manage to reset it.

Could it be (not as rare as it should) that the reset button is not working?

I would try opening the device and short the contacts of the reset button with a pair of tweezers, like:
http://forum.mikrotik.com/t/ccr1009-7g-1c-1s-broken-reset-button/175938/1

15

Reuse the case and put in a new RB ?

16

That is a good advice, inly if I can open the case, which I was not able to do yet. :slight_smile:
20250209_130826.jpg
I found another think that might help, under one of the rubber feet, there is a hole and in the hole there is a jumper.
I did try to use it and do a Router OS reset, but unsuccessfully.

What is the procedure using this jumper hole?

Also, somehow I was able to make te router looking like this, with all LEDs turned on:
20250209_130939.jpg
Does this mean anything?

17

The reset pad, which you discovered under ruber foot, has same function as reset button. So keep those pads shorted while applying power (and then for a while more) until netinstall starts to show signs. From own experience I can tell you it’s hard to keep pads shorted and plug power at the same time … for me, a Phillips screwdriver (with + shaped head) was better than flat one.

You may have managed to short pads while device was powered … so you may have succeeded in reseting device to defaults (in which case username is admin and empty password).

18

That contact is the same as the (possibly defective) reset button, use a cross (Philips) screwdriver to make the short.
http://forum.mikrotik.com/t/reset-button-on-rb750/41287/1

Check the behaviour of your device against this:
http://forum.mikrotik.com/t/bricked-rb750/122078/1
http://forum.mikrotik.com/t/bricked-rb750/122078/1

19

What is the problem?
There are two “clamps” visible on the picture of the bottom between the edge and mounting crosslike holes.
Just loose that clamps with a pocket knife or flat screwdriver and pry the cover.

20

Instructions from Mikrotik (for hap lite, but case is the same).
open_case.pdf (709 KB)