Possibly fried the connection for my heated bed...

Hello,

I recently built a Mendel i2 and unfortunately the wires for my fan (going into D9) came into contact with the wires for my heated bed (D8) and it partially melted. I caught it before it got toooo bad, but now when I go to use my heated bed it will heat up to about 100 C and then cool off. Do you know what could be causing that? Could I fix it by going into the firmware and making the D9 connection be for the heated bed? If so, where in the code would I be able to do that? I attached a picture of what the connection now looks like. Thank you!

Heated bed running up and then cooling down is often a problem with the yellow PTC 11A fuse on the Ramps board. You may have damaged it when you shorted things out.

Darn that's unfortunate to hear. Thank you for letting me know. Is there any way to fix it? Or should I just purchase a new board?

By *far* the best solution is to pull both of the yellow PTC fuses off of the Ramps board and replace them with nice heavy wire (what ever will fit in the holes). Then supply the power to the two +12 inputs through normal automotive fuses in normal automotive fuse holders.

Wow this is a great and cheap looking solution. Thank you so much!

Should I find two 11A automotive fuses? Or would other amperages work? Sorry for all of the questions, I just want to make sure that I don't hurt my board again!

You will spend a *lot* of time looking for 11A automotive fuses.....

One of the yellow beasts you pull will be an 11A and the other is a 5A. The 5A is easy. Automotive fuses come in 5A. I'd just go for a 15A auto fuse for the 11A. It's the closest you are likely to find.

Great, I'll try that this weekend and let you know how it works. I appreciate all of the help!

Hey Uncle Bob, just wanted to give you an update - that fix worked perfectly! Thank you again for saving my printer!

Now that you have off-board fuses you can make another modification:

There's no need to run from your power supply to the fuse, then onto the Ramps, then out to the heated bed. Just hook the "hot" side of the heated bed to the fuse. That gets rid of two connections that may fail and that certainly drop voltage under load.

You can do the same thing with the 5A fuse, but it's not as clean. You still need to get the 5A circuit to the board to run the steppers and other stuff.