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So, I blew a fuse on my Rambo tonight. Luckily, it was in the very beginning of the print. However, I have spent several hours troubleshooting the problem because of confusing information in the RAMBO wiki page.[img]http://i.imgur.com/50C8qoM.jpg[/img]
There are 3 fuses in the picture. F4 is the automotive style fuse up top. F3 is the beige fuse near the top of the board, F2 is the beige fuse in the middle of the board (note: there is no fuse in the F2 position in this picture, it was removed when I took the picture.) On the wiki it states that the F2 fuse is for the motors and on-board power supply and F3 is for the extruder and fans. I thought this meant that F2 supplies power to the board; however, this is incorrect. F3 is the fuse necessary for the board to operate. If it is blown, the board will not power on. This might just be me being dumb, but hopefully it will be helpful for someone in the future.

You mean no fuse in the F2 position...I'm sure you meant to say that.

Up through version 1.1b, F2 supplied logic power. You also had the option of powering logic from USB via a jumper.
After that, logic power was moved to F3. USB was isolated and no longer an option for power.

It's in the wiki, but if you miss it, it certainly could confuse you:
http://reprap.org/wiki/Rambo#Powering_RAMBo

Woops, changed that, good catch. I see it now on the page for v1.2 that it says that F3 powers the logic, however, I was looking at the troubleshooting section, and it links to the Rambo v1.1 page, which has no mention of the board logic.

F3 on mine blew up too. Any idea why this happened. I know replacing the fuse is not a permanent solution.

Although, this is not a delta. I have a Lulzbot Taz 5 Dual extruder. Am trying to find the root cause. Any help is appreciated.

Have you messed around with the fans at all recently? Check them for loose connections, as well as for wire fatigue. You may also have better luck actually inquiring to Lulzbot, as they would have more experience with their printers.