ramps 1.4 smoking when heating the bed

I have just built a Prusa i3 clone using the Ramps 1.4 board, and while it has been printing PLA fine, I have been unable to print in ABS as the bed has not been able to maintain the temperature.

I have been testing heating the bed while printing PLA and the prints get killed only a few minutes into the print due to the bed temp dropping slowly. It heats up to the required temp OK, but can't keep it there.

I have only been heating it up to between 60 and 80 degrees, and then yesterday I tried heating it up to 110 and after a while the ramps board started smoking...coming from underneath the stepper drivers somewhere.

I shut it down and then after leaving it overnight, I tried it this morning without turning on the heated bed and it prints fine, but as soon as I start heating up the bed, I get the smoke.

I gather this means a new board??

If I have to get a new one, does anyone have any advice on a better type of board to get? Preferably something that will fit in with my current configuration, without having to change much.

The mosfet the controls the heated bed on most ramps is criminally under rated for the job

The connector for the heated bed on the ramps is also criminally under rated for the job

All cheap ramps are like this.

They don't even put a heat sink around the bed mosfet, as per the design spec... thus they save 20c and we pay for it with a house fire...


If you use a ramps, replace the heated bed mosfet with something better eg IRLB 8743 (this doesn't need a heat sink)
and replace the connector with something rated for 11amps and not 5amp as supplied on most.

Im guessing the smoke is really coming from either of these... its quite tricky to catch where smoke is really coming from.

I'm not the best at soldering circuit boards, so don't know how I'd go at replacing the mosfets, but I think I'll give it a go.

If I do as well as I expect and totally stuff the board up, would you recommend going with one of the newer Ramps boards that have the better fuses and mosfets already installed, or are there better boards than that that would suit my configuration?

Read this it may help you.

[forums.reprap.org]

I'd personally not bother with ramps at all. The MKS GEN and MKS base are much better boards, with an extra mosfet you can use for another extruder or a fan and the bed mosfet ar capable of enough amps. They cost about the same as a budget ramps clone and budget arduino mega clone together. And are pin/firmware compatible with ramps.

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slippyr4
I'd personally not bother with ramps at all. The MKS GEN and MKS base are much better boards, with an extra mosfet you can use for another extruder or a fan and the bed mosfet ar capable of enough amps. They cost about the same as a budget ramps clone and budget arduino mega clone together. And are pin/firmware compatible with ramps.

I have been looking at that board and wondering if it was any better. Do the same A4988 stepper drivers fit the MKS board?

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vfwfw
I have been looking at that board and wondering if it was any better. Do the same A4988 stepper drivers fit the MKS board?

The MKS GEN, yes - it takes "standard" polulu type plug in drivers. The BASE has integrated (not replacable) A4988s.

I have used a gen on a 24V printer with a bed running about 220W so about 9A and it's fine; the printer I have with the MKS base has 12V and about 17A and the MOSFET doesn't get warm.

I don't think there's a lot out there in the budget category that's better than these boards. Of course, if your budget is higher then you have a lot of quality options.

Thanks slippyr4, I think I will give the MKS Gen a go.