fuses popping constantly

[Cale]

Recently a small fuse popped on my MAX v2.I wasn't sure what caused it but I replaced the fuse anyway.Today I tried cleaning the hot-end.While I was getting the tip off,the same fuse blew.My dad thinks there is something wrong with the heater.I checked the wires at the hot-end,but none of them are touching.At the board everything checked out ok.So what is wrong?I also noticed during the latest heatup of the hot-end the extra filament inside came out as weird little droplets.What is causing that?
Can you please tell me how to solve this.
Thanks,
Cale

[teoman]

You could be shorting the resistors on the hot end.

[Eaglezsoar]

I agree with teoman.
You need to have your meter set to measure 12 volts and measure the voltage going to the hotend while jiggling the wires around
that run to the hotend. There should be shorts while jiggling and detected on the meter because the voltage on the meter should
drop to zero instead of 12 volts. Something in your wiring is shorting out and blowing the fuse.

[teoman]

Or you can put your multimeter to continuity mode (beep beep) and put the ends on to the 2 wires at the rambo side. While fiddling with the hotend if you hear a beep then you have a short.

You may want 2 people for this.

[guanu]

with the power OFF! never mess with the hotend when the machine is on... the 12v rail is always on, and the grounds are what are switched.. so never mess with it while the machine is on

Guanu

[Earthbound]

Continuity checker may be fooled by the low resistance of the hot end circuit and be unable to distinguish normal from shorted.

[teoman]

And indeed the flukeing continuity checker is fooled by the low resistance. Well then you have to set it to ohm (resistance meter), and look for a sudden drop in resistance while fondling the hotend. My hotend is 4.4 ohms.

And having the machine off is how you should be doing your tests. Or your testing could burn more fuses or damage the machine or cause injury to yourself.

[Cale]

Thanks everyone for all the help.I've solved why the fuses popped both times.
After a lot of thought I remembered it occurred when I was taking off the nozzle for the hot-end.It is very likely I accidentally touched a wire with the wrench I was using. My little mistake.

Cale

[teoman]

Do you mean that you were changing the hotend with the power on? Or that you sqished the hot end resistors' open wires to touch the aluminum heater block, and experienced shorts thereafter?

[Cale]

What I mean is that the power was ON(to make cleaning the nozzle easier).I was using two wrenches (one to keep the main hot-end from moving,and one to loosen the nozzle).It is very likely the first wrench touched one of the resistor wires and blew the fuse.

Cale