Heated bed issue

Hi Everyone,

I have another printer down and I am stumped as to what the cause is. It is a Creality CR10s Pro and the heated bed has stopped working. I installed a new replacement bed , but it won’t heat up either.

As I was double checking that everything was hooked up correctly, the solid state relay (I think that’s what it is) came apart from the printer base. It had apparently been subject to an attempted previous repair using some kind of cement but has now completely separated from the mounting plate.

Has anyone else had this issue before? I am hesitant to order a replacement part if this isn’t the problem. However as the relay is between the power source and the heating element I have a gut feeling this might be the solution.

Any advice would be very much appreciated.


There seem to be a lot of these keeling over and dying lately.

The two wires at the bottom are the control input. When heat is required, there should be a voltage across these terminals (could be as low as 5V or as high as 24V, depending on the printer - I’m not familiar with the CR10s Pro internals).

If that input voltage does not change when demanding heat, then the motherboard (controller board) is fried.

If there is an input signal but no heat on the bed, check the voltage across the thicker output terminals.

NOTE: when no signal exists on the input, the output voltage should read 24V (or 12V depending on the printer). When the input voltage is 5V/12V/24V (printer dependent), the output voltage of the Solid State Relay should read close to (but probably not exactly) 0V.

If the output remains at 24V (or 12V), when an input signal is present, the relay is fried.

If the output is 0V when the input is 0V, you have a wiring problem or a defective bed.

You didn’t indicate it, but if the printer reboots when you call for heat, you have either a wiring problem (short) or a defective power supply.


There are a lot of CR10s failing. It is a warranty issue I’d have Reality replace the whole printer. You bought the printer you are not being paid for R and D or Quality control. The sad fact is you are doing both now. Reality steals ideas from its clients and then uses them to re assemble the printers they buy to correct poor QC.

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Thanks Legomaniac and Kitedemon!

I’ll get a volt meter or a multimeter and check the terminals.

I agree that I’m not being paid to troubleshoot Creality’s products for them. Unfortunately the printers are at least a few years old and my employer doesn’t have the purchase info anymore.


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I was going to agree with @LEGOManiac that to check the relay (for some reason i thought it was a MOSFET, but im mo electronical engineer)

Anyway did you figure out what the issue was?

A Solid State “Relay” is usually a MOSFET, although for AC applications, they can be built with TRIACs as well. The difference being that a MOSFET can be turned on and off by applying a signal to it’s “gate” input, whereas a TRIAC can only be turned on by the input signal. A TRIAC stays on after the input signal is removed and only turns off when the current through the TRIAC reaches (nearly) 0, which, for an AC signal, it does twice every cycle. They are the basis of every household light dimmer you’ve ever used.

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