Bed Temperatures Hop (Repetier Host)

Ok, so I use the "Alunar" Prusa i3 (Amazon if you're curious), and I just replaced the power supply because the bed temp would never get hot enough to make it beyond 82C... ever...

Now, it seems like it does keep climbing with the new power supply, but at around 82.2C the temperature jumps to 95C. If I have the bed set at 90C, it keeps heating higher and higher as it never reached it's 90C mark. If I set it around 95, it keeps jumping between 82.2C and 95. I've decided to keep it at 96C until I figure out the issue.

Attached is the temperature curve. Everything else is honkey-dorey, it would seem, with exception of the temp jump. Is there something I need to reconfigure for this skip to stop happening? Is this repetier host or my new power supply?

Thanks!

I had a similar issue with my hot end, turned out to be a loose connection to the thermistor, I double check all your thermistor connections as a first move.

Moriquendi

I checked. Nice and solid connection to the print bed, and not loose at the board.

I read somewhere that I may need to modify the thermistor table or something? Like it could be as simple as it was not calibrated properly. What do you think?

Unfortunately I've never used repetier host so I wont be much use with that.

Moriquendi

Sounds like the issue with the temperature file.
The config.H file calls a temperature file for your sensor This file will probably have one of the values in the wrong order. By that I mean one row is misplaced. This causes the interpolation to be wrong and you get this big hang around 83 degrees and then a rapid rise above about 93. The file is a text file with a list of 2 values. I think the 1st is the temperature to report, the 2nd is the digital value resulting from the sensor signal. I can't remember which way they go as one value is in ascending order and the other descending. But they must be in order.
I have this on my machine with preloaded software. Its also been seen in other users files when they have posted on this site.
The supplier should have supplied the raw data so you can check. The solution is to use a correct table and reflash the controller. Since I run my bed at 110C I have just put up with it.

The temperature jumping around is almost certainly a wiring problem to the thermistor.

I recently had a problem where the temperature was jumping and it turned out to be a high resistance short between the power supply (via the heater wires) and the thermistor. I first noticed that there was a problem when I switched the 24V power on and off and the temperature reading would jump. A bad wire, or more likely a bad crimp connection between a wire and the thermistor lead, will cause a temperature reading to jump.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Would it cause it to jump at a specific temperature every time? You'd think it would be at different random intervals, but it jumps to the from and to the same temp every time. I think it's the controller, but I also don't know much about wiring.

It prints... can't complain too much. I just really wish there was support for this ANET board. I've seen one other person with this exact issue on another forum and he had the same board and issues.

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drephuz
Would it cause it to jump at a specific temperature every time? You'd think it would be at different random intervals, but it jumps to the from and to the same temp every time. I think it's the controller, but I also don't know much about wiring.

It prints... can't complain too much. I just really wish there was support for this ANET board. I've seen one other person with this exact issue on another forum and he had the same board and issues.

I have the same problem. Anet A8, Repetier Host. Bed temperature always jumps from 83C to 95C and back, it looks like there is only one degree between 83 and 95 somehow...

Check the temperature file.
As a practical test. Set the bed temp to 100C so it forces the heater on at 100% up to 100C.
Look at the temperature profile in repetier. The temperature should rise smoothly. You will see where an error in the table causes the reported temperature to change the slope of the curve.
This is repeatable because its a reporting error at these specific thermistor values.
In the OP you see this happen just after 57m at ~ 83C.
Interestingly the heater is not turning off until 58m so the bed control is working OK its just the temperature reporting that's the issue. I don't know how that can happen as they must use the same table. I can only assume that when calculating the target temperature its using a different algorithm.
Hopefully there is an attached example of the temperature file (not the one for your machine).

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burbilog
I have the same problem. Anet A8, Repetier Host. Bed temperature always jumps from 83C to 95C and back, it looks like there is only one degree between 83 and 95 somehow...

I know it's the firmware/board... I actually contacted the manufacturer, and after a week they replied in broken English asking me to lower the temp. I told them that I need the heat to print...

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MCcarman
Check the temperature file.
As a practical test. Set the bed temp to 100C so it forces the heater on at 100% up to 100C.
Look at the temperature profile in repetier. The temperature should rise smoothly. You will see where an error in the table causes the reported temperature to change the slope of the curve.
This is repeatable because its a reporting error at these specific thermistor values.
In the OP you see this happen just after 57m at ~ 83C.
Interestingly the heater is not turning off until 58m so the bed control is working OK its just the temperature reporting that's the issue. I don't know how that can happen as they must use the same table. I can only assume that when calculating the target temperature its using a different algorithm.
Hopefully there is an attached example of the temperature file (not the one for your machine).

I checked your temperature file example, but as far as I know the only way to change this is to write it to the board, yes? Would updated firmware (if it were available) be an ideal solution for this? Is there a way in repetier to figure out why the jump is happening, and to fix the issue? Or will I be relying on the manufacturer?