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Hotend issues after 4.2.7 board install

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Joined: 9 months ago
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For reference, this is an Ender 3 Pro with Micro Swiss hotend and Printermods direct drive kit.


I picked up the 4.2.7 mainboard and BL Touch kit for my 3 Pro and just got it put together last week. Install was super easy, everything played nice, flashed the firmware, verified the BL Touch was working properly, sent a test print, and everything went south. 

When trying to get up to printing temps of 200C+, it gets up to an indicated 150ish degrees, then seemingly stalls. Once it reaches that point for 30 seconds or so you can smell something is hot (that kinda sweet burning smell that plastic makes when it's really hot), and a few seconds later it throws a thermal error and beeps like crazy. Guess it's a good thing these new boards have runaway protection, huh? The bed heats up fine and is able to reach its set temp and maintain it with no issue. The thermal error on the hotend occurs with or without the bed being heated. Attempting a PID tune on the hotend yields the same results. Could this be a thermistor issue?

It doesn't appear that I've crossed any wires when migrating to the new board, I made sure to only move one wire at a time to prevent that from happening. No changes were made to the hotend or nozzle and I had successfully printed a file the day before doing this swap. I opened the printer back up and double checked all connections on the board to be sure they were solid and correct and ran another test with the same results. It seemed like all the wiring diagrams I found were different in some way, can someone 100% verify what the pinout is for the 6 screw terminals for the hot bits and thermistors on these 4.2.7 boards?

I really hope I don't have a bad board, the silent drivers are music to my ears after enduring the noisy 8-bit board drivers for over a year through dozens of prints.

This topic was modified 9 months ago by fooschnickens

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@fooschnickens Hi, I have exactly the same issue with a 4.2.7 board, bought as a standalone upgrade.  Heated bed is 100% fine.  Hot end heats up to temperature but then fluctuates by up to 15 degrees, so either very soon after starting printing, thermal runaway protection kicks in, or it just never settles on a temperature.  Thermistor is 100% OK, swapped in brand new E3D heater, same result.  Did you get any response from @creality support?  Alex

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Hi, I'm getting the same exact issue.

I replaced the thermistor for a brand new and the issue remains.

Only happening on 4.2.7, I had a 4.2.2 previously and it was just fine.