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RAMBo V1.2 Static Discharge protection patch fix

Posted by John Olafson on

We would like to start by saying THANKS to the folks at UltiMachine for their amazing support and customer service.  It truly is a measure of how well you do not when when things go right, but when things go wrong.  They excel at any and everything they do, and that's why we're happy to support them and use their electronics in all of our machines.

This past few weeks, here at SeeMeCNC HQ we've been receiving random RAMBo V1.2 boards back as defective, and have been stumped at what was causing some of the boards to fail?  They have the best record in the industry for being fail-proof.  Turns out, the onset of this winters cold and dry (low humidity) air brought to surface an issue with the newly designed V1.2 boards.

As with all their products, UltiMachine makes rapid improvements based on user feedback and filed experience.  One of the issues in the earlier boards was a ground loop situation caused by not having isolated circuitry between the USB communications and the rest of the board.  This , in a very low percentage of cases, could cause the boards to lose communication over USB, and sometimes worse.  So they designed the V1.2 to have isolation between the USB side and the rest of the board.  One of the components in the isolation circuit however, just wasn't up to the task of taking on thousands upon thousands of volts that can potentially be generated with static electricity from just walking around!  

The symptoms of having a V1.2 board with this problematic component are, having the ability to connect USB to your computer one day, and then all of a sudden you can't any longer.  The board will still function properly, using the LCD controller and SD card, but you aren't able to communicate and upload new firmware or connect to repetier host software.  

IF your board has lost communication over USB, unfortunately, it's going to need to be replaced.  Don't worry, we'll replace it free of charge.  Simply remove the board and send it back to us in the original box, or if you do not have the box, in a static proof bag and sturdy cardboard box.  THIS ONLY APPLIES TO RAMBO 1.2 BOARDS, the earlier 1.1 and older boards do not have an issue with the static discharges, as it's taken back thru the power supply, with no harm to the board or PSU.


Mail the RAMBo V1.2 board to


Attn:Static Rambo

65695 US Highway 33

Goshen, IN 46526


Do you have a V1.2 board and aren't having any issues with it?  Well, to be safe, UltiMachine has designed a user-serviceable patch that will bypass and protect itself in the event of super high voltage static discharge to the USB side of the board.  It's super simple to do, it simply plugs into two of the unused headers connections on the Board.  The pictures below will help you install the jumper fix to prevent any future issue with static and the RAMBo board.

If you are not having any issues with your V1.2 RAMBo board, and want to install the jumper yourself, please email and in the subject line put Static Jumper Mod for RAMBO and include your mailing address and your original order number.  We will mail you the jumper to install yourself on the RAMBo board.  Just follow the instructions below.  PLEASE don't forget to include your mailing address and original order number, without those two things in your email, we will not be able to send your jumper kit.


The instructions below are worded with the RAMBo board facing you, stepper drivers down, and the USB connector facing the left.

With the board facing the above direction, plug the large connector of the jumper into the SERIAL connector just to the right of the endstop connections, make sure the single wire in the plug is oriented to the TOP-LEFT position, use the pictures below to reference the correct direction.

The smaller connector on the jumper goes into the TOP-RIGHT position on the small "ICSP1" 6-pin header on the RAMBo board.  Once again, use the photos below to make sure it's in the correct position.  


Thanks again for all your understanding, and we hope you're happy with out resolution to the problems.  If you have any further questions, please feel free to email us with them.

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