Fuckitfuckitfuckit. Yet another RUMBA corpse to go next to the other 2 ex-RUMBAS I own. 
This one has a blown USB port. DO NOT BUY A RUMBA!
Time to look into a new one - As usual, azteeg are out of stock of their X3. I could be persuaded towards 32 bit if they weren’t so damn expensive. A good quality RAMPS board with high ampage heated bed mosfet would suffice. Any suggestions?
I strongly recommend KOS from @Pawel_Dobrowolski - http://sklep.pjd-automatyka.pl/index.php?id_product=18&controller=product
(single board, small size, screw terminals)
Thanks @Jarek_Szczepanski for recommendation;) If you need KOS1.2 I accept paypal payment and abroad shipment 
SAV Mk1? only one extruder though…
http://www.reprap.org/wiki/SAV_MKI
http://www.kitprinter3d.com/electronica/16-sav-mki.html
With whole respect but SAV don’t have any basic filtration at step/dir signals. It is simply clone of teensylu. I’ve started KOS1.2 from teensylu 0.9 and I know what is wrong with this board (simply most of all). here you have source: https://github.com/syntetyczny/KOS
Email Roy at Panucatt about the azteeg. He might have one he isn’t listing on his site since some people use them in their kits.
fair enough, it’s just my suggestion for what I believe to be a solid board. I have no stake on SAV, just like it 
I’ll try your’s when mine burns or something
@Marius_Araujo you are welcome
@Pawel_Dobrowolski Is there an English version of that page? I’d like to read about your board.
@Pawel_Dobrowolski time to list the KOS at http://reprap.org/wiki/Comparison_of_Electronics perhaps, for a birds eye view of its’ place in the eco system.
@Tim_Rastall Check why the boards fail. Almost all boards are copied from other boards. They will fail the same way as the RUMBAs.
All boards (including many arm boards) have very limited protection.
@Pawel_Dobrowolski I checked the KOS schematics on github. There is no added protection. What is the purpose of the step/dir filtering? Was a pulldown on the enable inputs not good enough? Why are there 15k pulldown resistors on the USB lines? These should be at the host side not the device side.
@erik_vdzalm
What kind of protection would you like to have? Fuses? Gretz bridge?I assure you, whatever you put into board will not protect it as well as a good manual and double check of connections.
Stepper drivers make loud noise at signal lines, and this simple filtering helps clean step/dir pulses. It was common that loose moving axis were causing damage to microcontroler.
I’m using this kind of filtering for a month, and it helps in filtering noise from the power grid.It is not perfect emc filtering but works good enough. More about filtering d-/d+ lines is in intel’s usb2.0 document.
SAV MKI or RAMPS 1.4sb
Perhaps something in the air, I blew a ramps hot bed connection this weekend. Upon reading a little, noted my 12x12 bed at 95 degrees is beyond the designed limits. Looking into the repair/ beefing up circuit.
@Carlton_Dodd Sorry, but currently I’m working at polish manual for KOS1.2 all you can “read” is in schematic but it will change!
@Pawel_Dobrowolski I am not talking about reverse polarity protection. I mean simple ESD protection etc on the I/O lines. I doubt that reverse polarity killed tims board.
I do not know what you mean by “It was common that loose moving axis were causing damage to microcontroler.”
The resistors on the USB lines are wrong. You violate the USB standard. Check the USB standard its free.
Why did you place a pulldown resistor to the stepper N_EN lines? Now the steppers are enabled when the board is in reset.
And you connected AREF to VCC. This is also wrong. The firmware selects AVCC as ADC reference, Then you should only connect a C to AREF. (I know this is also wrong on many other boards.)
@erik_vdzalm Check the datasheet of at90usb at page 316 from page AVR.
@Pawel_Dobrowolski Section 26.6.2 on page 314:
“If the user has a fixed voltage source connected to the AREF pin, the user may not use the other reference voltage options in the application, as they will be shorted to the external voltage. If no external voltage is applied to the AREF pin, the user may switch between AVCC and 2.56V as reference selection.”
The firmware selects AVCC as reference.
@erik_vdzalm I can read, what is your point?
@Pawel_Dobrowolski You have AREF connected to an external voltage. All reprap firmware versions and arduino select AVCC as reference.