Hi, I just replaced my bed heater wires on my FlashForge Creator Pro because they burnt at the heater wire connector. 3 days after the wire connector has burnt again??! How can I stop it from burning and what is casing this to burn/melt? I have uploaded some images of the wire connector and the connector to the bed. Please let me know ASAP. Thanks.

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I did not replace the bed connector the first time, do I need to do that?

You need to remove the connectors and solder thicker wires directly to the board. Take a look at this.

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Yes, you must replace the connectors. The original one is only rated for 7.5 Amps at room temperature and is not even sufficient for the current required for the heater at room temperature, let alone when it gets to operating temperature. The heater when it first starts running needs around 8.4 Amps. The connector gets loose and starts arcing, which heats it more and increases its resistance, continually making it get hotter (for a while), until it eventually burns enough to melt the connector and lose connection entirely or worse.

As long as your heater board’s copper traces didn’t delaminate when it melted, the heater itself should be fine. But I highly suggest replacing the connector with a DigiKey ED1609-ND part or similar screw terminal block connector instead, which is rated at 15A. And, replace the flimsy wires that FlashForge used with nice 16 gauge silicone insulated wires. Also, you can connect the +24V (+) side of the heater directly to your power supply and avoid routing both paths of the current through the mainboard. You will, however, still need to connect the (-) side of the heater to the connector on the mainboard so that its MOSFET transistor can continue to switch power for it.

You can also make the wires a little shorter. The original cable is 1 meter long (as they used an off-the-shelf part and coiled up the excess). It only needs to be about 750mm. So you can trim off 250mm or 10" of extra wire and reduce voltage drop in the wires. It will make your heater work better by heating the heater rather than the wires powering it.

I think your wires are not soldered properly and require the assistance of an expert. Find out the proper places for the wires to be soldered and while printing, do check the heat settings of your 3D printer.