Monoprice i3 2nd wire to fail, heatbed positive at terminal, probably another bad crimp like the ground at the power supply that failed a while back. It actually finished the print in this state, somehow. The bed kept to temp as the connection overheated. Examining it separated the solder connection, just fell apart.
I have heard I can connect the bed positive directly to the PSU as the switching is in the ground wiring? Can anyone confirm that and maybe describe it? Board seems to work but I don’t want to try and clean up the bed heater +V pad on the PCB, it is very messed up on top under the terminal plug.
I only asked it to do 80c bed for a 3 hour PETG print. I am sort of surprised I did not think that was such a huge load even for the infamous Wanhao/Monoprice wiring.
Thinking of just getting a new board, since I apparently must replace all the wiring
Would warranty it, but it’s so modded and braced returning it to stock for return would be a serious PITA, as would then reinstalling all the frame brace mods and realigning a new unit that is likely to have just as bad of wiring and need all that replaced as well anyway. What would you do?
Positive rail is just attached to the positive power input from the PSU. The ground is switched with an NPN transistor. Hook bed up to positive power from PSU, ground to the ground pin for the heated bed. That’s all there is to it.
The connectors are said to be at their limit for heated beds, so seeing a melt down is common. I use a “30A Portable Power Switch 12V DC Electric Current Amp Transfer Board Relays High Current Control Module for Cooler Heater Refit Water Heater Control”, and I paid less than $9.00us.
It is virtually identical to using a solid state relay, here is a video https://youtu.be/TiEwNf1H_Tc
I hooked it up the same but using my power supply instead of using mains power, and the switch i used is dc/dc.
@Jeremiah_Coley - Thank you! I will check this out. I’ve been doing some mods lately and @Vernon_Barry mentioned this issue on my Facebook 3D printing group which made me check my wiring. Thankfully my wiring looks great but it’s just a matter of time before mine could melt down.
Ya when I start my 3d printer journey, I read about every problem I could find and electical was huge. So I decided to make the mods to protect my controller boards (mega 2560 and ramps 1.4) Tom’s guides are a really good source of information hell all of his videos are. Best of luck with this one.
