If you have worries about the connection between your main board and your heated

(Derek Cameron) #1

If you have worries about the connection between your main board and your heated bed being too vulnerable to shorting out and possibly causing a fire, then I would recommend a simple upgrade like this. Connecting a DC in/DC out solid state relay (think of it like a switch) between the main board and heated bed makes the PSU and the relay do the heavy lifting. It also helps protect the main board as it only turns the “switch” (SSR) on and off while the voltage needed for the heated bed comes directly from the PSU.

(Tim Elmore) #2

If the main board is properly designed/specced, there is no need for this.

Also note that eBay SSRs have an affinity for catching fire.

(Derek Cameron) #3

@Tim_Elmore That’s a fair statement that I should have pointed out. With my printer, there’s a common problem with the heated bed cable melting at the bed connection. And yes, you have to be careful about the SSR you order on eBay. So far, mine hasn’t even gotten warm even during a print.

(Tim Elmore) #4

Good ole Rigidbot, using pin headers to carry ~10 amps.

(Sutsawat Thetsakaan) #5

Good idea

(Daniel F) #6

After I burnt 2 cheap ramps, I also odered a DC/DC SSR. The connectors on the cheap Ramps (6$ including shipping) can’t handle the high current of my 350W heater that pulls around 15A@24V in the long run. So it really depends on the size of the heater. Went with 230V for my new printer I’m building at the moment. Hope to avoid trouble due to high current/bad connectors in the future.

(Daniel F) #7

@Derek_Cameron What settings are you using in the firmware? PWM or bangbang?
I’m asking because I just installed a new Ramps and a Fotek DC/DC SSR (40A) the same way you did. It works but the SSR heats up quicker and gets hotter than the bed. I did not change my settings so maybe the SSR does not like PWM.

(Tim Elmore) #8

@Daniel_F Sounds like one of those delicious eBay SSRs, extra crispy coming right up!

(Derek Cameron) #9

@Daniel_F I’m honestly not sure…I actually never changed any of my firmware settings. I just wired it up and so far it has worked fine. Even during mid-print it stays cool to the touch.