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Thermal runaway of hotend AND bed  

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james.s38
(@james-s38)
New Member
Thermal runaway of hotend AND bed

I think my Rambo/Einsy board failed in a dangerous way.

My newly assembled printer worked fine for 4-5 hours the day I assembled it, very nice prints

The next day when I turned it on(print hasn't started yet) get a bit of a sizzling/snap sound, about 20 seconds later the MAXTEMP alarm was going off.

Powered it off, let it cool off and tried it again.
As soon as it powers on(no preheat/no print running), the bed and hotend just get progressively hotter.

Seems like a control board problem since both try to heat up.

I used the shop contact page, https://shop.prusa3d.com/en/contact-us , not sure if that is correct for hardware/tech support

I couldn't find any other way to officially contact prusa3d

Posted : 24/04/2018 3:37 am
Chris
(@chris-19)
Reputable Member
Re: Thermal runaway of hotend AND bed

sounds like something welded in the on position.

To contact chat go to the eshop https://shop.prusa3d.com/en/ bottom right corner is a chat window, select tech support and chat with them. they will help you fix it.

in the meantime i'd unplug it just in case

Posted : 24/04/2018 7:20 am
james.s38
(@james-s38)
New Member
Topic starter answered:
Re: Thermal runaway of hotend AND bed

Thanks Chris, chatted with tech support, new einsy rambo seems like the fix.

Posted : 24/04/2018 4:24 pm
Craig Trader
(@craig-trader-2)
Eminent Member
Re: Thermal runaway of hotend AND bed

Speaking of thermal runaway, I was looking at the Prusa Mk3 Firmware configuration ( https://github.com/prusa3d/Prusa-Firmware/blob/MK3/Firmware/Configuration.h ) and I see at lines 355-364 that the thermal runaway protection is disabled.

Could someone explain why these aren't enabled by default?

I solve problems, usually with computers ......
Posted : 24/04/2018 5:09 pm
sean.h8
(@sean-h8)
Honorable Member
Re: Thermal runaway of hotend AND bed


Speaking of thermal runaway, I was looking at the Prusa Mk3 Firmware configuration ( https://github.com/prusa3d/Prusa-Firmware/blob/MK3/Firmware/Configuration.h ) and I see at lines 355-364 that the thermal runaway protection is disabled.

Could someone explain why these aren't enabled by default?


// temperature runaway
#define TEMP_RUNAWAY_BED_HYSTERESIS 5
#define TEMP_RUNAWAY_BED_TIMEOUT 360

#define TEMP_RUNAWAY_EXTRUDER_HYSTERESIS 15
#define TEMP_RUNAWAY_EXTRUDER_TIMEOUT 45

From
https://github.com/prusa3d/Prusa-Firmware/blob/MK3/Firmware/variants/1_75mm_MK3-EINSy10a-E3Dv6full.h

🙂

It's on.

edit: I actually had it happen to me once.

My power went out for 10 minutes, and apparently my UPS, can't handle everything on it, and the hot-end, started cooling down. And the printer shut it off, saying "thermal runaway".

Hi, I'm Sean. I used to work on CNC machines.
I try to not make mistakes, but the decision is YOURS.
Please feel free to donate to my filament/maintance fund....
Posted : 24/04/2018 5:32 pm
Chris
(@chris-19)
Reputable Member
Re: Thermal runaway of hotend AND bed


Speaking of thermal runaway, I was looking at the Prusa Mk3 Firmware configuration ( https://github.com/prusa3d/Prusa-Firmware/blob/MK3/Firmware/Configuration.h ) and I see at lines 355-364 that the thermal runaway protection is disabled.

Could someone explain why these aren't enabled by default?

you are seeing the full marlin code. Prusa has its own variables for all of the sensors on the einsy. So the marlin is commented out and the prusa, (linked by sean below) has the prusa runaway code.

Posted : 25/04/2018 8:26 am
james.s38
(@james-s38)
New Member
Topic starter answered:
Re: Thermal runaway of hotend AND bed

In the failure mode on my board logical/digital fail-safes won't matter, the einsy doesn't think it's running the bed or HE.

I haven't been an electronics tech for years, but I'm guessing something failed(or cascaded failure) on the far side of the mega 2560 outputs. Doesn't matter what signals are sent, both heaters run 100% after power on.

Don't know if this is the victim or offender...

Even if I was clever enough to figure that out, not enough motivation to install Altium

Posted : 26/04/2018 1:33 am
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