Hot End Issues, not heating up now

[mcdaigle]

Hello, I finished the Mechanical and Electrical Assembly on my Rostock MAX. I calibrated, configured, and tuned the hot end changing the values in the calibration.h file and all everything was running along smoothly. Configured the slicer program with the settings and hit go ready to print or try to do something and the Hot end would not heat up, It just stayed at room temperature. What can I check for voltage, continuity,.... I have no Idea what happened, it heated fine for the tuning but will not move temperature now. Thanks.

[mcdaigle]

On another note if for some reason they did contact the hot end are the resistors junk now, and if there was contact does it blow a fuse of sorts or why would my rambo board not be putting out any power to them once they seem all fine and clear.

[johnoly99]

Mc, the resistors wouldn't go out if they did short to the hotend. Odds are, you blew one of the tiny fuses on the RAMBo board. Check the two small white ceramic fuses, one of them is prob. bad. Geneb has a documented fix for modding them to use more standard automotive fuses, because honestly, it makes more sense. The small fuses were needed for the footprint on the board, but are hard to source locally.

[mcdaigle]

We have a pretty good electronics store locally, any idea of part number for reference or cross reference.

[mcdaigle]

Anyone have the link to the automotive fuse upgrade, I have searched the forums and cannot find it.

[geneb]

mcdaigle, you just solder (carefully!) some 24ga wire to the top surface of the fuse cap ends and then solder the other end to a small automotive fuse. It's 5A I think.

I can provide a photo if you need one.

g.

[theverant]

How often are the fusing blowing on RAMBO?

[mcdaigle]

Just the one time, I was able to source the fuses locally and I bought three a couple weeks ago to have a spare and I have only replaced the one that went teh first time. I believe what happened was my connected wires on the hot end touched the aluminum hot end and popped the fuse.

[Polygonhell]

How often are the fusing blowing on RAMBO?

I blew one shortly after I got mine running.

I replaced the 5A hotend fuse with a 10A one, I posted the part numbers in the RAMBO forum, it's been trouble free since.
You can tell if it's blown, because the LED's under the connectors don't light up, there are 3 separate fuses, one for the heated bed (this is a thermal fuse just like RAMPS) and two solidstate 5A fuses, one for the steppers, and one for the Hotend connections.

IMO although my math says it should be fine, the SeeMeCNC hotend pulls about 2x the current of other reprap hotends, so there isn't a lot of additional overhead on the 5A fuse. Why Ultimachine decided to use solidstate fuses is beyond me, other than perhaps board space.

[truenorthtrader]

Figured out which fuse it was, it's the top one by the power plug that I circled in red for the Hot End.
I believe the lower one under the plug is for the Stepper Motors.

This is for anyone who needs to do this I soldered a 7.5 Amp car fuse to it and my Hot end works fine now.

Someone one else said a 10 amp is good too but I only have a 7.5amp and a 5amp
A

[jmick]

I found that its best to go ahead and order 5 of the 10amp little fuses to avoid having to solder on the aq board. I put one in at the beginning of Sept and have not had another problem.

[truenorthtrader]

Yes this is true helped alot!

[PartDaddy]

Could you post which hot end you are using?