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today i turned the printer on and rise the temp of the nozzle to 240 to change the nozzle
then when i was trying to hold the hotend with a wrench suddenly the screen turned off and no blinking lights from the bored
all i hear is the PSU fan...
is it possible that i short something in the hotend with the wrench? this is the only thing i can think off.

A short seems a likely cause, given what you were doing. Check the fuses on the Rambo.

Eric wrote:A short seems a likely cause, given what you were doing. Check the fuses on the Rambo.

i sure hope so
where are they located?

Thank you
i don't have a replacement fuse but i ordered a couple.
however by looking at them can i identify a bad one? i mean the small ones (they look ok to me)
also the big one is for the heated bed so i can skip checking that.

mrbdrm wrote:Thank you
i don't have a replacement fuse but i ordered a couple.
however by looking at them can i identify a bad one? i mean the small ones (they look ok to me)
also the big one is for the heated bed so i can skip checking that.

You need a multimeter set to measure resistance. If the little fuse shows a short it is good, if it shows
that it is open, then it is bad.

I had the same thing happen. The screen went blank when I was trying to remove the nozzle. The hot end got twisted. Something in the hot end could be broken but there isn't much info about how to troubleshoot.I just ordered fuses but am concerned that the blown fuses may be a sympton of another problem. How do I troubleshoot this? I've emailed support and chatted with the online person. No email response for 5 days and the all the chat session told me to do was email support. I really need some help here.

drknow1 wrote:I had the same thing happen. The screen went blank when I was trying to remove the nozzle. The hot end got twisted. Something in the hot end could be broken but there isn't much info about how to troubleshoot.I just ordered fuses but am concerned that the blown fuses may be a sympton of another problem. How do I troubleshoot this? I've emailed support and chatted with the online person. No email response for 5 days and the all the chat session told me to do was email support. I really need some help here.

I doubt that anything got broken. Anytime you are working on a hotend or its components get it up to the temperature you need and then shutoff all the power. The twisting and turning on parts like the
hotend causes the resistors to momentarily short and if the power is on fuses blow. Carefully inspect the hotend before turning the power back on, and make sure none of the resistor wires are touching
heat block or anything else that can short them out. Just a tip, if you ever need to replace a resistor in the hotend, instead of resistors use the 40 watt 12V ceramic cartridges that they make now. I
believe they should be 6mm in diameter.

Same thing happened to me a few weeks ago when I changed my nozzle on my Max v2. I blew one if my nano fuses on the board. There are three of them. Pop each one out and connect it to your multimeter to find which one is dead. Luckily for me I live close enough to SeeMeCNC that Oly gave me a few for spares. Btw, you'll need some tweezers to get to those things.

heathenx wrote:Same thing happened to me a few weeks ago when I changed my nozzle on my Max v2. I blew one if my nano fuses on the board. There are three of them. Pop each one out and connect it to your multimeter to find which one is dead. Luckily for me I live close enough to SeeMeCNC that Oly gave me a few for spares. Btw, you'll need some tweezers to get to those things.

Please guys, bring your hotend up to temp for the removal but turn off the machine just before working on it. If you don't start working this way one day you will blow more than a fuse and if not under warranty those rambos are
expensive. I am not getting down on anyone, I just want everyone to turn off the power before working on what ever you intend to fix.

Yup. You nailed it Eaglezsoar. I'll only make that mistake once. Perhaps someday the crew over at SeeMeCNC can include a small and concise packaging slip for every aftermarket nozzle that they sell stating that same thing.

When you rotate the hot end, you can easily short out the heating resistors by either touching them with the tool, or twisting them so the resistor wires contact the hot end.

g.

geneb wrote:When you rotate the hot end, you can easily short out the heating resistors by either touching them with the tool, or twisting them so the resistor wires contact the hot end.

g.

Which is exactly why the machine should be off - unplugged when doing these kind of operations. Bring it to temperature, turn off the power then remove the nozzle.
Have the tools you are going to use at the ready so you will not have to find them.
When reinstalling inspect closely to make sure the resistor wires or any wires are contacting something they shouldn't be.

You say what's the big deal, it'll just blow a fuse. Sometimes you blow the card and that is a big deal.

I fixed the issue it was a fuse. Thank you
wish someone guided us before, it would've save us the trouble of finding out the hard way
when i searched for the right way to change the nozzle they all say heated up then twist while its hot, never said turn the power off.
a simple sticky guide from one of you guru will save a newbie in the future