MINTEMP BED - Printer Down!  

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david.p87
(@david-p87)
New Member

Ok, so I've been printing just fine since October. Now I get this error when I preheat (MINTEMP BED).

When I first turn the machine on, I see 27/0 for the hotend and 0/0 for the bed.

When I try to preheat, I get inconsistent results, but ALWAYS ending with a MINTEMP BED error before the print starts.

My room (i.e. environment) is fine - not too cold.

I tried following the KB notes for this and swapped the 2 thermistor leads on the mobo, when I try preheating in this state I see 27/0 for each when I first boot up the machine.

When I try to preheat, I get a MAXTEMP BED (I think this is what it said) error.

So, at this point I am not sure if the THERMISTOR or BED is bad - any ideas? Should I next contact Prusa or should I try something else?

Printer is dead in the water until I can resolve this...

Thanks!
Dave

Quote
Posted : 02/04/2019 2:36 am
charles.h13
(@charles-h13)
Active Member

Ok, I had the same issue.

My issue was a broken wire at the area where the wires hit the back edge of the bed for the THERMISTOR. I removed theTHERMISTOR from the bed, cut the wires 3 inches from the connector in the to the Einsy and 3 inches form the THERMISTOR. I then soldered (spliced) two new pieces of wire to connect the two parts. I shrink wrapped the new wires to protect them and I have had no issues since.

You could also just buy a new THERMISTOR.

ReplyQuote
Posted : 02/04/2019 3:30 am
david.p87
(@david-p87)
New Member

I see no obvious damage to wires. Is the Thermistor covered by warranty or should I just get one of Amazon? Anyone have experience with replacing theirs?

ReplyQuote
Posted : 02/04/2019 6:00 pm
charles.h13
(@charles-h13)
Active Member

I see no obvious damage to wires. Is the Thermistor covered by warranty or should I just get one of Amazon? Anyone have experience with replacing theirs?

You will not see damage to the wires. It is a solid conductor. I found the board in mine.

It is covered by warrantee.

ReplyQuote
Posted : 02/04/2019 6:05 pm
david.p87
(@david-p87)
New Member

How did you know your wire was broken? I am totally not following you. 🙂

Thanks though for replying to me on this...I appreciate it.

ReplyQuote
Posted : 02/04/2019 6:31 pm
charles.h13
(@charles-h13)
Active Member

How did you know your wire was broken? I am totally not following you. 🙂

Thanks though for replying to me on this...I appreciate it.

How did I find this? Google. I read online that this was a common problem.

I cut the ends of the thermister wires out. I took the center that was left and confirmed a lack on continuity from one end of the wire to the other. It was broken in the middle. I did not find the break physician. I confirmed it with a micrometer. I replaced the center with a heavier wire. No problems since.

ReplyQuote
Posted : 02/04/2019 7:23 pm
david.p87
(@david-p87)
New Member

Ah - gotcha. I assumed you meant you physically saw a break in the wire. I'll reach out to Prusa and see if I can get a replacement...

Thanks again!

ReplyQuote
Posted : 02/04/2019 7:52 pm
charles.h13
(@charles-h13)
Active Member

I did the same an now I have back up.

ReplyQuote
Posted : 02/04/2019 8:34 pm
rohit.s3
(@rohit-s3)
New Member

Same problem. Intermittent MINTEMP BED error. Issue was damaged thermistor wire where the sleeve attaches to the bed. The clamp pinched one of the thermistor wires - and the back and forth motion broke the inner strands over a month of printing.

Fix was to remove the damaged section of the thermistor wire, splice in 2 cm of flexible wire, a bit of heat shrink, and put the clamp back on. No problems since.

ReplyQuote
Posted : 06/04/2019 4:29 pm
derek.k2
(@derek-k2)
New Member

I had the same thing happening to my farm printers right around 3,000 hours. The spiral wrap and sleeve just don't distribute the motion throughout the harness.

I wound up modding 11 of my Prusa machines with a cable chain for the y-axis only: https://www.thingiverse.com/thing:3434799

So far I've put another 3,000 hours against the farm without issue. I take the sleeve/wraps off before installing the chain.

-D

ReplyQuote
Posted : 07/04/2019 4:14 am
david.p87
(@david-p87)
New Member
randolph.l
(@randolph-l)
New Member

are you planning to make your own case and potting those naked glass bulbs in your own aluminum tubes?

just get the real sort that have the right length of wire and the right connector for the controller board...
https://www.printedsolid.com/products/prusa-mk2-mk3-thermistor-cartridge

ReplyQuote
Posted : 07/04/2019 11:23 pm
joan.t
(@joantabbymail-com)
Ms Moderator

I believe Printed solid are currently out of stock...

try your local E3d reseller

https://e3d-online.com/resellers

regards Joan

I try to make suggestions that I believe to be well founded and safe,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

ReplyQuote
Posted : 08/04/2019 3:28 am
david.p87
(@david-p87)
New Member

Yikes. I thought those thermistors I found on Amazon were good replacements...the E3D you pointed me to appear far more "industrial" grade. 🙂

MatterHackers good source?

I am also confused over which thermistor to get for the bed. The image above is for the bed or the hotend?

-Dave

ReplyQuote
Posted : 08/04/2019 5:58 am
david.p87
(@david-p87)
New Member

Also, I found this video which also shows the multimeter in use! yay

ReplyQuote
Posted : 08/04/2019 6:12 am
gilles.p3
(@gilles-p3)
New Member

Ok, I had the same issue.

My issue was a broken wire at the area where the wires hit the back edge of the bed for the THERMISTOR. I removed theTHERMISTOR from the bed, cut the wires 3 inches from the connector in the to the Einsy and 3 inches form the THERMISTOR. I then soldered (spliced) two new pieces of wire to connect the two parts. I shrink wrapped the new wires to protect them and I have had no issues since.

You could also just buy a new THERMISTOR.

Does the splicing have an effect on the accuracy?

ReplyQuote
Posted : 09/04/2019 11:29 am
charles.h13
(@charles-h13)
Active Member

Ok, I had the same issue.

My issue was a broken wire at the area where the wires hit the back edge of the bed for the THERMISTOR. I removed theTHERMISTOR from the bed, cut the wires 3 inches from the connector in the to the Einsy and 3 inches form the THERMISTOR. I then soldered (spliced) two new pieces of wire to connect the two parts. I shrink wrapped the new wires to protect them and I have had no issues since.

You could also just buy a new THERMISTOR.

Does the splicing have an effect on the accuracy?

Not even a percent of a degree.

ReplyQuote
Posted : 09/04/2019 12:13 pm
paul.h38
(@paul-h38)
New Member

Just to put another reason for error message into the pot - Mine was after about 2kg of filament use and some very large objects or multiple smaller objects. The error occurred after a while of printing and then a shorter time after restarting. Help from support asked me to measure resistances of thermistor and heater. The former was ok but the latter was not a stable reading. Investigation found that the two connections that were bolted to the bed had worked loose so I tightened them - the reading was now good and stable at 3.2 ohms. Printer now working fine...

It seems that there can be multiple reasons for the same error message, a few tests should work out which it is. I had also tested by using hair drier on bed when cold and temp reading rose ok. I also checked for intermittent readings whilst in pre-heat by moving the x and y axis slowly and sometimes jerking them.

Machine is a Mk3S KIT from mid February 2019.

ReplyQuote
Posted : 16/04/2019 1:52 am
gilles.p3
(@gilles-p3)
New Member

My thermistor broke exactly where it goes into the little bracket on the heated bed. I guess it causes too much strain

ReplyQuote
Posted : 16/04/2019 11:45 am
charles.h13
(@charles-h13)
Active Member

My thermistor broke exactly where it goes into the little bracket on the heated bed. I guess it causes too much strain

That is about where mine broke. I just did an autopsy of the old wire.

ReplyQuote
Posted : 16/04/2019 1:53 pm
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