I Can't Get A Break

[printbus]

printbus,

I understand. My board is currently running on type 99, I think. Will switching to 33 affect anything else or is it even possible to change specifically the pin for the heat bed? I just ordered a heat bed relay to use D9 and for future use because it seems that I probably should have used one in the first place. I like the 20020109-H061A01LF that gmay3 pointed out, but will I be able to solder a connector to the heater cartridge and heat bed relay safely? Typically for those pins the connectors are attached to a very high gauge wire, like 22 gauge for example. Will the connectors and wires be able to support the level of current going through them?

And will the polyfuse being out of the loop introduce any new possible dangers? Should I enclose the heat bed relay in some sort of plastic enclosure so that in the case of it shorting or this issue happening again the enclosure will melt on it? I'm actually pretty paranoid because of this.

There is no board type 99... At least not in the latest Marlin code.

I just realized I was confused on where the RAMPS board used the push-on connectors. I thought they were on all the wiring ports. Glancing at the printer now I see only the power input uses the push-on type. Some of my earlier words about push-on connectors don't apply. The smaller polyfuse is also 5 amps, not 1/2 amp as I initially posted. 5 amps provides enough capacity for the cartridge heater, but not the heat bed. At least the help is free.

If it were me, I'd stick with the WM7857 terminal block approach to eliminate any flakiness with the push-on connector scheme. Some have had intermittent issues with those on the power input connections and removed them. Regardless, according to the datasheet linked through DigiKey, the push-on connectors have a current rating of 12 amps, so no issue there. The datasheet doesn't specify a wire size, but the 12-amp current limit implies it should be able to accept a pretty large wire gauge - maybe as large as #14 AWG? The MK1 bed and cartridge heaters are likely prewired with #16. If you go with the push-on connectors, remember that you have to order two parts - the part that gets soldered to the board and the part that the wires are connected to.

I don't want to offer you direction on the polyfuse. Running without any protection would be like 99% of us that use a heat bed relay. Without any protection, you're depending on what the power supply will do in a short circuit condition. One approach to a compromise would be to add an in-line automotive fuse in the heat bed power circuit with something like a 15 amp fuse installed. That way if there's an issue the fuse would open up likely before anything burns up. You'd have to replace the fuse after that, but no big deal, right?