Welcome to the SeeMeCNC Community

Hey everyone,

Hope all of you are experiencing perfect prints with perfect temps and no other problems! Haha, anyways, I have been looking through these forums for an answer, but it seems I may be the first one to ask. What is the actual name or typr of resistor that goes on the bottom of the Rev 8 heat bed? I think that could be the problem when my temps go DEF. The reason I say this is because all day, literally ALL day I have been trying to find the source to my temps/thermistors failing and when I was applying the Kapton tape back to secure the bed wires (I had given up for the night), I accidentally moved the resistor and like magic, the temps showed up on the LCD and no more DEF. I will definitely replace the resistor as I believe that was the culprit all along. I guess I just didn't think that had that big of an impact on the entire operation. What do you all think? I am open to ideas.

also, I have replaced the bed thermistor two times today with new ones, didn't remedy the DEF. Also using a brand spanking new HE from Seemecnc (factory assembled for warranty). Just thought that would be relevant to share.

thanks in advance and I hope that if someone else is having the same issue, that this thread can help them as well.

Which resistor are you talking about (i have the v2).

On mine there are resistors on the bed to limit the current going to the LED's.

You do not really need them. But they should also not affect the operation of the thermistor.

Have you tried resoldering the resistor?

Perhaps your resistor is improperly placed, and you are shorting out the thermistor instead? Like Teoman said, the resistor is only for limiting current to the led.

I have the V3. Yeah, I know it limits the flow to the LED and was surprised that the temps changed when moved it. I tried that trick again this morning and of course the resistor snapped off. Now i'm off to waste another day looking for that thing. Customer service blows. They don't have a phone number and their support emails sometimes take a couple days.

What else should I be looking for regarding the heat bed, when dealing with random DEF temps? Replaced thermistor, checked solders, even resoldered. Ideas?

When you start up the printer, what are the temperatures that it reads before it goes DEF?

moo77777 wrote:When you start up the printer, what are the temperatures that it reads before it goes DEF?

NOZ: 33
BED: 13

skyjuice wrote:

moo77777 wrote:When you start up the printer, what are the temperatures that it reads before it goes DEF?

NOZ: 33
BED: 13

It's the bed thermistor reading low. Below ~14C, it will error out. You can either adjust the Beta value in the firmware to correct for this, or reduce the temp at which it errors. Alternatively, if it actually is that cold, move your printer somewhere warmer.

Xenocrates wrote:

skyjuice wrote:

moo77777 wrote:When you start up the printer, what are the temperatures that it reads before it goes DEF?

NOZ: 33
BED: 13

It's the bed thermistor reading low. Below ~14C, it will error out. You can either adjust the Beta value in the firmware to correct for this, or reduce the temp at which it errors. Alternatively, if it actually is that cold, move your printer somewhere warmer.

Thank goodness it's not that cold! I built a laboratory in my garage with a nice electric baseboard heater I also replaced the thermistor and now it's been running for abour 15 hours with no hiccups!!