Partway through my enclosure build, I noticed a burning smell coming from my 8″ Makerfarm Prusa i3. After sniffing around to find the source, I discovered that the power connector from my power supply to the RAMPS board had started melting on one of the ground contacts!
After a bit of web investigation, it turns out that this is a common problem caused by an inadequate connection. When I built my printer, I had originally joined the leads with some solder to make them easier to insert into the power bus. However, this also makes them harder, and unable to be crushed by the terminal contacts. In an unsoldered stranded wire, the strands are compacted by screwing down the terminal, enabling a better connection. In my case, the poor connection meant more electrical current through a smaller channel, which makes heat!
When I received the replacements, I had to figure out how to install them. I turned to Youtube for some guidance on desoldering components. Unfortunately, however, there are 4 pins on this connector, and I wasn’t able to get them all liquid at the same time to pull out the connector. So, I had to do some destructive desoldering, where I pretty much flexed and bent the header terminal enough to rip the plastic from the metal leads. Then I was able to desolder the individual leads from the board and remove them. Luckily, I didn’t damage the board and soldering in the replacement terminal was easy!
Crisis averted… back to printing!
Update: It’s been about a month since this happened and I haven’t had any problems. I think that rigidly mounting the controller board and power supply have also helped the situation by reducing the amount of flexing and movement that the wires see.