Jumpy extruder temperature

[RepMike]

Hi, I wanted to get into PETG printing, so I wanted to print a temperature tower from 245 to 230.
The problem: After climbing up to the 245°C region, the temperature is jumping between 241°C and 249°C and the print actually never starts, not even after 15 minutes of waiting.

I've done a PID tuning of the extruder and it didn't help:

Code: Select all

M303 E0 S240 C8
M301 P13.81 I2.48 D19.24
M500

What else can I try in order to be able to use higher temperatures?
So far, the highest I've ever tried with this printer has been 205°C with PLA.
Thanks in advance for any hint

Edit: Here's an example for jumpy temperatures at 230°C

Bildschirmfoto von »2018-10-15 19-07-14«.png (61.03 KiB) Viewed 12249 times

[RepMike]

I've found out that when I want to print at higher temperatures around 245 or so (for PETG), I can trick out the printer by starting at around 225 for the first layer and then change the temperature to the higher temperature, but that only worked for a few times, now it's not working anymore.

The printer now stays at the above picture (or see newer picture down below) and then at some point I interrupt the printing process after an hour or so, because there's no sign of life except for the heating.

What's wrong? Is the Thermistor broken? Is the heater broken? Does the stock firmware have a problem?

octoprint-IMG_3645.PNG (353.79 KiB) Viewed 12177 times

[RepMike]

I think I'm getting closer ... seems that the Thermistor of the extruder is broken. See this Video on Youtube showing the temperature not being stable when I power up the A10. This shouldn't range from 15 to 20°C. It is 20° in this room and not less.

Question: Which connector is the Thermistor of the extruder?

Mini-Panel-Extruder-IMG_9285.JPG (122.56 KiB) Viewed 12130 times

[_kaktus_]

Hello.

A10-EXT_CON-1.jpg (27.59 KiB) Viewed 12123 times

In my opinion, connector no. 1. is: thermistor,
no. 2. is heater,
no. 3. & 4. fans.

If you have a multimeter, you can easily verify it.

Check the stability of connections.
When observing the temperature readings, touch the connectors, move the cables.

[RepMike]

The Impedance of the Thermistor is fine, it is at a stable 101.6 kOhms, which is fine for a 100k Thermistor. BTW, the video I made shows temp of the heated bed, not the temp of the extruder, but that's instable in the same way. I highly doubt that I have to exchange the Thermistor.

BTW, I've tried both, the stock Marlin 1.1.8 which the printer was delivered with and Marlin 1.1.9, both no difference in the behaviour.

One other thought: How about the Thermistor on the hotend? Would it be worth trying to use another one from the software side?
Currently I have this one:

Code: Select all

/**
 *     1 : 100k thermistor - best choice for EPCOS 100k (4.7k pullup)
...
#define TEMP_SENSOR_0 1
...

I do not want to play around as I do not want to break the hardware unless anybody knowing about these sensors tells me more details.

I'm lost for now.

[RepMike]

I'm still having this problem and my printer is still unusable for PETG and ABS for the above reason.
It's unbeleivable that no support is helping me or offering me any alternative. However, I have to at least mention Kaktus who looked at my problem and helped me with some thoughts.

I think I will modd this printer away towards a better and working printer, but obviously I'd have to exchange a lot.
I will start with the board, but for the rest, I don't care to document. Good luck that I have another printer so I can print my parts for that.
For this printer I say Good Bye Geeetech and thank you for the fish.

[_kaktus_]

Hi


Still tell me if you tried to adjust the PID algorithm

[RepMike]

Hello, yes, in my first post in this thread I have written about what I've done regarding PID tuning.

[_kaktus_]

I forgot about it and preferred to make sure.

Still tell if you have been monitoring the stability of the main power supply voltage.

[dekes1]

I had the same inconsistent temperature with a heater cartridge that was going bad. It worked properly up to about 200C but would fluctuate like yours above that temp. I'd suggest replacing the cartridge since they are inexpensive.

On a side note, if you intend to print at 240c or above, you will damage the stock PTFE tube as well as release poisonous fumes above 245 or so. You need to upgrade to Capricorn blue PTFE tubes or possibly an all metal hot end.