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[Solved] Bed Preheat Error  

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Edgar
(@edgar)
New Member
Bed Preheat Error

Hello to all...

I guess this topic is fully disclosed several times, yet I couldn't find my specific answer.

I got this error in an MK2S with 3.10.0 firmware... after switching to silent mode in Power and Notifications. I don't know if this is a cause or not...

The fact is that I've measured several things in the board and connectors and everything seems OK:

- 12V in board's connector (both entry and exit to the bed)

- 12V reaching the bed (in Bed's soulder)

- Continuity of wires (bed and thermistor) OK

- Thermistor of the bed working and sending information to the board (I could see this by disconnecting it and also by reading the temp in the display after approachig a lighter to the thermistor)

- No fuses melt or broken

 

I'm really out of clue but I'm thinking that is the bed itself... Might be?? What can broke in the bed!?

 

Thank you very much for you help!

Best Answer by JoanTabb:

Hi Edgar, 

the Heatbed power wires can fail intermittently open circuit, after they have been used for a while.

You have a Mk2, so it's been in use for a while... 

I think Silent mode slows the motions a little, and this may make the intermittent power problem more apparent...

I have replaced my heatbed power wires with 16AWG   Flexible, Silicone Insulated wire, and not had any problems since

You need a good soldering iron to unsolder, and re solder the connections. 

afterwards Make sure that the Nylon support filament is  correctly installed, and that the wires are not touching the wall behind the printer, as the Y axis goes backwards, this error will increase the liklihood of future failure.
the PRUSA heatbed power wires have 21 strands of relatively thick copper in each wire, 
the Flexible Silicone insulated wire, has 252 strands of thin wire, making it more flexible and less likely to fracture in the future.
16AWG flexible silicone wire can handle 22 amps, which is more than the entire rated output of your power supply.
so it can easily handle your heatbed...

You could use 14AWG Wire, but it would be a lot more difficult to solder onto the heatbed
Regards Joan

Posted : 04/10/2021 11:27 pm
JoanTabb
(@joantabb)
Moderator

Hi Edgar, 

the Heatbed power wires can fail intermittently open circuit, after they have been used for a while.

You have a Mk2, so it's been in use for a while... 

I think Silent mode slows the motions a little, and this may make the intermittent power problem more apparent...

I have replaced my heatbed power wires with 16AWG   Flexible, Silicone Insulated wire, and not had any problems since

You need a good soldering iron to unsolder, and re solder the connections. 

afterwards Make sure that the Nylon support filament is  correctly installed, and that the wires are not touching the wall behind the printer, as the Y axis goes backwards, this error will increase the liklihood of future failure.
the PRUSA heatbed power wires have 21 strands of relatively thick copper in each wire, 
the Flexible Silicone insulated wire, has 252 strands of thin wire, making it more flexible and less likely to fracture in the future.
16AWG flexible silicone wire can handle 22 amps, which is more than the entire rated output of your power supply.
so it can easily handle your heatbed...

You could use 14AWG Wire, but it would be a lot more difficult to solder onto the heatbed
Regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 05/10/2021 7:31 am
Edgar liked
Edgar
(@edgar)
New Member
Topic starter answered:
In fact, it was the wires!

I ended up finding that the problem was in the wires, doing an intermittent connection, exactly as you said!

I'll consider those wires you said in order to provent this in the future! Thank you!

Posted : 05/10/2021 9:35 am
JoanTabb
(@joantabb)
Moderator
My Crystal ball, worked!

Cheers Edgar, 

Good luck with the new wires

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 05/10/2021 10:30 am
Edgar liked
JoanTabb
(@joantabb)
Moderator

as a temporary fix, i used 2 lengths of substantial mains flex(uk 13 amp flex), for each conductor

this gave me service while i waited for the silicone insulated wires

 

joan

 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 05/10/2021 10:10 pm
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