Heated Bed wiring meltdown

**sniffle** · 03-21-2015, 04:09 PM

right i get that, i meant about the 5 second rule and your wires being at 1 second

**paintz2007** · 03-22-2015, 04:55 PM

It is painful to hold the wires for longer than 1 sec

**sniffle** · 03-22-2015, 10:15 PM

ahhh gotcha, worked all weekend going to get a new relay tomorrow. I'll check it and see after replacing it. my current relay actually melted internally from the resistance... all i can think is that i didn't crimp hard enough... but who knows... I'll find out soon enough

**eghm** · 05-15-2015, 05:00 AM

My D8 stopped powering my heatbed tonight. D9 works, I don't see any burns on the side of the board I can see, I assume it's the same terminal issue others have reported.

**lakester** · 05-15-2015, 08:30 PM

Since you're "in that neighborhood", perhaps it would be worth going with a relay as well.

I don't know what the numbers are for the 8", but a relay couldn't hurt..., especially if you've possibly burned out a mosfet being run close to a limit.

Out of curiousity, do you mostly print PLA or ABS? (i.e., what are your typical bed temps?)

0.02USD.

Originally Posted by eghm

My D8 stopped powering my heatbed tonight. D9 works, I don't see any burns on the side of the board I can see, I assume it's the same terminal issue others have reported.

**eghm** · 05-15-2015, 10:58 PM

Originally Posted by lakester

Since you're "in that neighborhood", perhaps it would be worth going with a relay as well.

I don't know what the numbers are for the 8", but a relay couldn't hurt..., especially if you've possibly burned out a mosfet being run close to a limit.

Out of curiousity, do you mostly print PLA or ABS? (i.e., what are your typical bed temps?)

0.02USD.

Thanks for the suggestion, I'll keep it in mind. I've only printed PLA using a bed temp of 65.

Something odd might still be going on. I haven't changed anything other than using D9 instead of D8 and it seems the bed will no longer heat when I go to print. I have to explicitly preheat then print.

**eghm** · 05-17-2015, 04:46 PM

An update on my heating bed challenges. Sometimes after preheating and starting the print the bed temp runs away rather than the bed not maintaining heat. My current work around is disconnecting one of the bed power wires. I'd be thankful for any ideas.

**mccallum** · 08-10-2015, 04:48 PM

According the the wiring diagram Colin has on his website for the relay board, J2 is just a jumper to connect power supply ground to heatbed gnd....you can tell by the traces on the board as well.

Why not run a dedicated 12AWG ground wire (Silicon wire) from the power supply ground directly to the heater bed Gnd and bypass the relay board J2 terminal altogether? Connect the +12V leads to the relay board as they were before. While you are add it you might as well change the +12V wire to 12AWG Silicon wire from the heater bed to J1 'Out' Pin...to allow for more flexibility as the bed moves back and forth.

Thoughts?

hb_relay_diagram_1.jpg

**printbus** · 08-10-2015, 05:08 PM

Originally Posted by mccallum

...Why not run a dedicated 12AWG ground wire (Silicon wire) from the power supply ground directly to the heater bed Gnd and bypass the relay board J2 terminal altogether? Connect the +12V leads to the relay board as they were before....

Yes, you could bypass use of the J2 terminals.

**usarmyaircav** · 03-31-2016, 02:39 PM

Sorry to revive an old thread, but I am looking for clarity. I have the I3v 10" with Ramps, and looks like one of the connectors on the relay melted down, can someone point me to the correct 40A automotive relay, and also an accurate wiring schematic?