Rambo board dead?

[jeffhuber]

I turned off the printer rather quickly mid command because it wasn't responding. When i tried to turn it back on, the LCD didn't come on. yikes. I took out the rambo, and looks like when I turn the power on - the rambo fan does run, but no LEDs turn on. I visually inspected the fuses and they all look "normal" (including F3 which apparently can cause problems). I have a multimeter but dont know how to use it .

I would so appreciate any advice on next steps!!!

[guanu]

look at your multimeter, it should have a symbol like this:

[img]http://ww2.justanswer.com/uploads/theho ... y_test.jpg[/img]

or at least the lines like a speaker type symbol... that is continuity... set your meter to that (have your machine off) and to test, touch the ends of the probes together... your meter should make a tone... if so, you are on the right setting.. now put the 2 probes on each side of F3 fuse (you can see the metal on each side of the fuse, thats what you want to touch, one probe on each side at the same time) if you hear a tone, the fuse is good... if not, test F2... its a tougher to blow fuse, and you should get a tone... if you do on F2 and not F3, then F3 is a blown fuse... let me know if you can follow that

Guanu

[jeffhuber]

You. Are. Awesome. Great instructions!

Got a tone on F2, and not on F3. so f3 is blown. ugh.

Where can I buy an F3 fuse?

[jeffhuber]

nevermind, i found it! when i get the fuses, how do you replace them?

[guanu]

anything you can use to get in there and grab the sides of the resistor and pull it out.. again make sure the machine is off, and I've used some needle nose pliers to get it out and replace.. glad you were able to figure it out!

Guanu

[jeffhuber]

thanks Guanu! super helpful as always =)

[jeffhuber]

It's working again! hooray!

for future reference, what might cause a fuse to break?

[Polygonhell]

F3 is on the mosfet outputs (but not the heated bed), so shorts or excessive current draw in any of the mosfet lines i.e. Hotend heater or fans.
Having said that my F3 went almost immediately shortly after assembly, and I'm pretty certain I didn't short anything, the replacement is still in there. I think the 5A fuse is somewhat marginal. Most hotends using resistors to heat use a single roughly 5.5Ohm resistor rather than the 2 SeeMe use on the stock hotend, and I suspect the original 5A value was selected with this in mind. Given the roughly 40W the hotend alone can draw there isn't a lot of leeway and I suspect a small power surge is enough to blow it.

[Eaglezsoar]

These fuses are available at a 10 amp rating and the instructions on the Rambo site says that 10 amp fuses can be used.

[jacquessavoie]

Solve

[jacquessavoie]

Ok,
After a research, I found fuse F2 and F3.
My F3 is dead.

Jacques

[jeffhuber]

the good news is that it's very cheap, on $1, and very easy to fix, just pull up (i used a pair of tweezers) and then push the new one back down. easy!

[jacquessavoie]

I put new fuse in F3. 2 minutes after starting printing it blow off the same fuse again.
Do you have the number part for the 10 A fuse?
Do you have an idea what cause this?

Jacques

[Polygonhell]

If your blowing F3 more than once, you really want to check your hotend wiring, I think the 5A fuse is marginal for 2 hotends, but it shouldn't be blowing regularly with the standard hotend, unless you have some sort of intermittent short. If you do have something wrong with the wiring, all going to a bigger fuse will do is increase the likely hood that next time you blow something more expensive

[jacquessavoie]

Ok, I found my problem.
Nothing to be proud of.
Just my unplug fan wire that touched one of the axe colonne.
So far, all my littles mistakes has cost me around $100 and 3 weeks lost.
But it's all part of the learning process I presume.....

[Eaglezsoar]

If you still need the part number for the 10 amp fuses, you can use 576-0448010.MR which are 10 amp fuses from Mouser.

[jeffhuber]

that is the learning process =) it's worth it!