Hot End Stopped!

Hello everyone,

So today I was trying to print a fairly simple print. 1/4 of the way through I looked over and no filament was coming out. I quickly looked at my pronterface and it was saying "Cold Extrusion Prevented" So I sent the command to check the hotend temp. It was dropping rapidly. Now I cant get it to get any heat. Everything else works great, all the stepper motors, the heat bed, fans, etc.

Any idea why the heat stopped and how to fix it? My first thoughts are maybe the resister is just blown? I have never replaced it. Just want to see the communities thoughts to see if I am missing anything in my thoughts.

Thanks!

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Ryan
Quality Engineer & Hobbyist
thingsandtrains.blogspot.com

The easiest problem to fix would be a loose wire on the controller so check that first.

My next guess would be a break in one of your wires. It might not be obvious. If you have wires that flex all the time, the insulation may be intact but the metal core may be broken.

If you have a multimeter, check to see that the voltage does indeed increase when you turn on the hot end. If that checks out, replace the wiring between your controller and your hot end.

resistor may be blown. it needs a pwm of less than 200 to keep from frying, you can find settings in firmware. if you have bad luck with heaters then use heat cartridges. they are more forgiving, but a little more spendy.

The first step would be checking voltage at the pins where the hotend connects to the board. Should be 12v(of course) at the plug with hotend on, if not then your controller is the problem, maybe just a mosfet or fuse. If you do have 12v you need to look further down the line then. My guess would be a bad resistor/cartridge.

Good tips everyone, I will check tonight when I get home. I have a pack of new resistors on the way.

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Ryan
Quality Engineer & Hobbyist
thingsandtrains.blogspot.com

Ok so I think based on tjb1's comment I might have a bigger issue.
I plugged the printer in
Opened pronterface
Set heat temp to supply power to the resistor
Using my multimeter touch each side of the resistor
I get 0 volts.....
Does this mean it is something in my controller? Arg I have some stuff I want to print for Christmas so I need to get it up and running. The new resistors will be here next Monday (December 2) but now I dont know if that will be enough.

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Ryan
Quality Engineer & Hobbyist
thingsandtrains.blogspot.com

It could still be bad wiring. Try unplugging your extruder heater at the controller and measure the resistance between the wires. If you have an open circuit, then your wiring is bad. If you measure the resistance of your heating resistor, the next step is to check out the controller.

Quote
banthafodder7400
Ok so I think based on tjb1's comment I might have a bigger issue.
I plugged the printer in
Opened pronterface
Set heat temp to supply power to the resistor
Using my multimeter touch each side of the resistor
I get 0 volts.....

You need to check for volts at the board. Directly at the board. If you measured at the resistor end of the wires you are testing the board and the wires. Test only one thing at a time. First the board and if thats ok, then check if there are volts at the end of the wires. One thing at a time.. Good luck

After I turned it on and connected to it I set the hot end temp. Then checking voltage directly on the board I get 5V across the thermistor connectors and 0V across the hot end connectors. Any more ideas?

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Ryan
Quality Engineer & Hobbyist
thingsandtrains.blogspot.com

Assuming all your wiring going into the board is ok.. did you check it?
If there's no power in, then you're not going to get anything out. Check it.

Assuming there's a problem with the board then the easiest way would be to replace the board. Trouble shooting the board itself if its the board could get tricky, but could be as simple as replacing the FET which is pretty easy assuming you can solder 3 solder joints, have a soldering iron and a replacement FET on hand.

Like I said, new board is easiest. Make sure the power to the board is ok. A new board won't fix that if thats the problem!

What temp is the thermistor reading?

I'm using the Marlin firmware, and I found that if the thermistor is reading below 10-15*C, it will not turn the hot end on.

You should file a bug report with the marlin software here: [github.com]

If a report hasn't been filed already please file one. Make sure to follow bug reporting guidelines. Mention the software versions you are using, operating system and anything else that may be necessary to reproduce the problem.

low temps are a firmware setting in configuration.adv or configuration. look foe #define min_temp, this is where the mintemp is set. this prevents issues of bad temp measure causing heaters to overheat. it is a safety feature in firmware.