Hotend stopped heating, has voltage but low current

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l2smith2
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Hotend stopped heating, has voltage but low current

Post by l2smith2 »

My rostock max v2 stopped heating mid print. Using an e3d v6.
I've since replace the heater cartridge and thermistor. I am reading correct temps. Heater cartridge heats fine using a 12 battery but the printer will not heat it itself.
Replaced rambo fuses just incase. Rambo Hotend LED comes on peek fan comes on and heater cartridge is receiving 11.5V however the current is so low it can barely illuminate 12v LEDs if I plug them in instead of the hotend.

Has anyone got any ideas? Everything seems to function as normal just not outputting enough current to heat the hotend. Heat bed works fine along with everything else.
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teoman
ULTIMATE 3D JEDI
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Joined: Sat May 24, 2014 5:43 pm

Re: Hotend stopped heating, has voltage but low current

Post by teoman »

Hnm.

Check the resistance of your heated cartridge.

Also if you just replaced it, try to tune the pid again.


Where are you measuring the current? Reason for low current can either be that your board wants to output a low current or there is a high resistance somewhere on the circuit.

Check the input and outputs the rambo. Make sure they are not getting hot.

If bed is heating up ok then your psu should ve good. Just in case try heating hotend without heating the bed. If it does, the psu could be bad.
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l2smith2
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Joined: Mon May 25, 2015 6:27 pm

Re: Hotend stopped heating, has voltage but low current

Post by l2smith2 »

cartridge resistance is about 5.6 ohms.
I've tried running PID autotune but it just times out since it doesn't heat up at all. Hotend won't heat with bed on or off. nothing gets hot on the rambo. Everything appears as normal. The input on the rambo for hotend is about 12V

Is it possible to use the 2nd hotend ouput instead of the first? how would i set that up
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teoman
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Re: Hotend stopped heating, has voltage but low current

Post by teoman »

Did you solve it?

Sounds as if a pid tuning error. Something could have done funny things to the eeprom. Unlikely but it does happen.

Try increasing the P value and the max pid values.
When on mobile I am brief and may be perceived as an arsl.
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teoman
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Re: Hotend stopped heating, has voltage but low current

Post by teoman »

Are you seeing a voltage at the cartridge when the printer tries to heat AND when it is not trying to heat?

What is unusual is that you cannot have 11.5V and low current if the resistor (cartridge) is connected.
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Dale Eason
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Joined: Fri Mar 06, 2015 8:56 pm

Re: Hotend stopped heating, has voltage but low current

Post by Dale Eason »

What value of current did you measure? Sounds like you do not have a good connection between the rambo and the heater or the Rambo and the power supply.

Dale
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