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Fuse keeps blowing

Posted: Thu Aug 10, 2017 10:25 am
by obbears
The first two times the F3 fuse blew, in both cases the black Rambo board fan wire had become dislodged. So I made sure this time to solder it correctly. But the fuse blew again for the third time and LCD went blank right as I click to preheat the hotend. I checked the board fan wires and they had not popped off this time. I checked the hotend wiring to see if they were loose or touching something they shouldn't be touching but all seems fine. I do not have a layer or peek fan installed on my V2. So the layer and peek fan wires are just taped to the mesh loom. I untaped these wires and noticed that one pair of wires (not sure if it's the peek fan wires or if it's the layer fan wires) were connected and twisted together but other pair were not twisted together but may have still been in contact under the tape, I'm not sure. Are the layer or peek fan wires not supposed to be connected if they are not being used?

Re: Fuse keeps blowing

Posted: Thu Aug 10, 2017 10:46 am
by joe
If you connect the wires together that will create a dead short and surely blow a fuse. You are connecting a positive to a negative, a real no-no and if the fuse wasn't there for protection the wires would burn and possibly cause a fire.

If this is a stock V2 and you are not using a peek fan then you certainly should.

Re: Fuse keeps blowing

Posted: Thu Aug 10, 2017 11:40 am
by obbears
joe wrote:If you connect the wires together that will create a dead short and surely blow a fuse. You are connecting a positive to a negative, a real no-no and if the fuse wasn't there for protection the wires would burn and possibly cause a fire.

If this is a stock V2 and you are not using a peek fan then you certainly should.


I'm a little confused because before I had this fuse issue, I was able to successfully print the fan shroud and the layer fan wires (or it might have been the peek fan wires, not sure which is which) were definitely twisted together and didn't blow a fuse. Seems like you can connect the layer fan wires and not the peek fan wires? Is this the case because you can turn off the layer fan in MatterControl but there is no setting to turn off the Peek fan?

Re: Fuse keeps blowing

Posted: Thu Aug 10, 2017 1:48 pm
by Jimustanguitar
It's hard to fix the issue if you don't know which wires are which. Figure that out, and what's going on will likely surface.

The hotend fan runs all the time, so trouble with those leads could cause a short instantly without having to turn on fans or heaters... Seems like a good place to start tracing.

Re: Fuse keeps blowing

Posted: Wed Aug 30, 2017 11:47 am
by StrangedazePDX
Jimustanguitar wrote:It's hard to fix the issue if you don't know which wires are which. Figure that out, and what's going on will likely surface.

The hotend fan runs all the time, so trouble with those leads could cause a short instantly without having to turn on fans or heaters... Seems like a good place to start tracing.

Hi,
I'm new to all of this but just recently experienced this exact problem/situation on my Orion. I mishandled the extruder fan and broke it, removed the fan, the exposed wires touched and the screen went blank. I'm willing to dig in and replace the fuse but where would I start? Is there more than one fuse? Will it need soldering?

Thanks for the advice and help.

Re: Fuse keeps blowing

Posted: Wed Aug 30, 2017 2:42 pm
by Xenocrates
There are 3 fuses, of two types. The bed fuse (The larger), is a standard Automotive type. The others are nano fuses, which can be found at mouser/digikey/ultimachine, and are installed in holders, so no soldering is required. It's most likely that you need to replace F2 (somewhat oddly, F3 supplies the fans according to the wiki, but F2 supplies the logic, so it may be either or both.) Take the fuse out and measure the resistance of each one. Replace any fuse with a resistance over ~.1 (Your meter may be inaccurate. Measure one of the new fuses for a baseline, the proper resistance is in the neighborhood of .014, so .1 is pretty dead but not entirely blown, and will likely blow soon, if it's accurate)

Re: Fuse keeps blowing

Posted: Mon Sep 04, 2017 8:31 am
by Eric
You must be reading the old part of the wiki. F2 supplies the logic only on early boards (versions prior to 1.2). Logic supply has been on F3 ever since.

Odds are he has a 1.3 board, so look at this page: http://reprap.org/wiki/Rambo_v1.3#Fuses

Re: Fuse keeps blowing

Posted: Mon Sep 04, 2017 12:17 pm
by Xenocrates
Yeah probably. I rarely need any of that info for myself, so it's usually a quick google. If it's close enough for people to go find the fuse with a meter, it's good enough.

Re: Fuse keeps blowing

Posted: Sat Sep 09, 2017 1:31 pm
by StrangedazePDX
Eric wrote:You must be reading the old part of the wiki. F2 supplies the logic only on early boards (versions prior to 1.2). Logic supply has been on F3 ever since.

Odds are he has a 1.3 board, so look at this page: http://reprap.org/wiki/Rambo_v1.3#Fuses


This has been great advice and much needed help. It does appear that I have the 1.3 board. Those micro fuses truly are micro and I'd have overlooked those locations easily.

Thanks again, time to order some fuses and get back to some printing.