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So I have had an issue with the stepper motor that is used for the extruder on my rostock max over heating and melting the pla plastic before it enters the tube to go to the head. so I wanted to add a fan to cool it. this issue with over heating just started after more the 400 hrs of perfect use on the printer. I went to cut the wires for the fan that cools the head as they were not being used and I saw an arc and the lcd screen shut off. ROOKIE move I know. I am assuming that I burned out the main board. I checked all the fuses on it and they are all fine. I plan on purchasing a new board next week. the issue I have is that I bought the machine already built and calibrated and have no idea how to calibrate it. when I got the machine I was playing with the settings through the LCD controller and had the foresight to click save eprom to sd card. is this my saving grace and alls I have to do is load that eprom back onto the new board? or do I have to learn how to reprogram the new board. ive programed the ramps for my first h1 printer but don't know if its the same kind of process. any and all help is great.

Check those fuses again. One of them should be blown. The RAMBo will likely be fine once the fuse is replaced.

Reprograming and calibration are easy. And sooner or later you will have to do it.

However i do not think that your board is dead.

Did you also check the micro fuses?

I checked the main fuse and the two small square fuses. I took both of them out of the board to check them with a multimeter they both read fine.

For calibration, you should download the manual for the rostock, the procedures are in there. You may be able to bypass that for now with your saved eeprom file, but you should still know how to do it. Not everything is in eeprom, some things can only be changed in the software configuration files. Motor currents are one of those things (a possible cause of your hot extruder motor).

To answer your last question, the Rambo is basically an all-in-one-board version of the Ramps board assembly. There are some pin differences and extra features like digipots for motors, but the methods of loading software are the same as for Ramps. Reading the manual will help you there too.

I tend to agree with the others that your board probably shouldn't have been killed by what you described as the cause, although the F3 fuse testing good is puzzling. Are any lights at all lit on the board? Have you verified the power supply is delivering 12V? You can also check the F3 fuse in-circuit with your meter(set for dc voltage)...put your probe on one end of the fuse and the other probe on a ground (the black wires from power supply). Then try the other side of the fuse and ground. Both readings will be the same (12V) if the fuse is good.

Here's a reference page for your rambo board: http://reprap.org/wiki/Rambo_v1.2

my main question is why did the extruder motor just randomly start getting hot enough to melt the plastic it is feeding in after constant use since last January. I am at work right now but will retest the fuses when I get home. I did already check and verify that the psu is in fact putting out 12 V. I am not sure what the F3 fuse is? I tested the main blue fuse and then the two small square ones. there is one light on the board that blinks yellow. the lcd screen is not at all lit up or responsive.

the issue of the main board not powering up has been solved. it was a bad f3 fuse. the issue of the extruder motor over heating is still there. it never used to even get hot and had well over 400 hours of great printing. now it over heats to the point where it melts the incoming PLA. this issue was there before blowing the f3 fuse. I changed out the motor and the issue with over heating was still there. what to do?

Take the hot end up to temperature and turn the extruder drive by hand. If there's much resistance, you need to solve your problem at the hot end.

After that, you can turn down the motor current in the firmware and see if that causes different problems or add heat sinks and/or fans.

Glad the dead board turned out to just be the fuse.

The stepper motors are being used in a constant current manner, which means the coils are generating the about the same heat all the time, even when they aren't moving. What's the ambient temperature of the room and is it warmer than in the past? Increased ambient temperature means increased motor temperatures as well. All of them, but the extrude motor is usually set a little hotter than the others.

You'll have to learn to load the software to play with the current setting. It's not a physical pot on the drivers like it was on the ramps board.

The extruder motor never used to get hot not even to the touch and I've printed in 85F ambient temps for upwards of 20 hours and never had a problem. now all of the sudden I have an issue where the extruder stepper motor gets hot enough to melt incoming PLA within 15 minutes of starting the print with the ambient temps below 75F.

Does your printer happen to be located near an air conditioning vent or a desk fan that is no longer running because the season is getting cooler?

no it is in my breezeway. no fans, no a/c, no open doors, not next to anything but my tablet that I use for printing. its on a glass desk. It is the only electrical thing in the room. this is why I am struggling to come up with a cause. I don't want to just strap a fan to it because that is just masking the problem not fixing it.

BenTheRighteous wrote:Does your printer happen to be located near an air conditioning vent or a desk fan that is no longer running because the season is getting cooler?