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Heaters randomly turning off

Posted by AndrewW09 
Heaters randomly turning off
June 23, 2020 03:23PM
Hello all, so I have a folgertech prusa i3 style printer. Ive had it for many years now and it has always been great. last year I upgraded to dual extruders and couldn't get it working correctly. Im finaly getting time to work on it and I have everything working properly, both extruders are recognized and operate correctly when I am manually running them. The problem is when I turn on the heatbed and both extruders, they will heat and then randomly turn off. It is a 12v 30 amp atx power supply. I am only pulling about 15 amps when everything is on. Once they stop heating the amps start jumping around and dropping to zero. I can print fine with just one extruder. I will attach my Firmware below. Thank you for any help.
open | download - Configuration.h (16 KB)
open | download - Configuration_adv.h (13.8 KB)
Re: Heaters randomly turning off
June 23, 2020 09:09PM
A short or break in the second extruder's heater circuit? One thing to look at closely is where the wires enter the cartridge. If they have been bent and straightened a few times, the wire breaks and only conducts when in a specific position. Another possibility is that only some strands break and splay out and then short to the other conductor. This would only have an effect when that heater was on, and again would be intermittent as the nozzle moves around and the wires bend and move. When shorted, there would be lots of current but no heating of the nozzle. In either case, the firmware might detect that the heater is on but the temperature is falling and turn everything off.
Re: Heaters randomly turning off
June 30, 2020 06:58AM
Check your PSU specification. The total watts or amps is usually distributed over the different voltage outputs so you can't have it all on one 12v out put. Typically 15amps is the highest on a 12v output. So it could be you are causing the temperature protection on the PSU to activate after some time. If there is more than one 12v output you can combine them.
Max current would be drawn during the heating phase when all the heaters are turned ON.. When bed and hot end are at temperature the power is modulated to maintain the temperature. Hence you can see the current fluctuating as it turns the heaters on/off.
May not be your issue but offered to aid understanding.
Re: Heaters randomly turning off
July 08, 2020 09:16AM
Everything looks good but I will give it a closer look, Thanks for the idea!
Re: Heaters randomly turning off
July 08, 2020 09:18AM
I will have to check the PSU, this would make sense according to how its acting, thank you.
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