A20T Temperature failure

[davides]

Hi,

I just received my printer a week ago, and now the printer seems not to be able to go past 180C. If I leave the printer disconnected for a day, and try to do a PID calibration, the printer can reach the desired temperature only during the first minutes, but after that temperature drops to 180 at most. After that first period it takes a really long time to reach only 180 and a temperature failure error is displayed.

If I heat the bed at the same time the effect and time it takes to heat the hotend seems to be the same, so it does not seem a PSU power fauilure.

First attempt after startup:

DeepinScreenshot_Seleccionar área_20200503112925.png (90.73 KiB) Viewed 6653 times

Later attempt:

DeepinScreenshot_Seleccionar área_20200503122857.png (83.73 KiB) Viewed 6653 times

[William]

Hi, you can check it.
1. Is the temperature abnormal? Under the normal non-heating state, the temperature shows room temperature 20-30 ℃
      1>. If the temperature display is very high, you can try to unplug the thermistor wiring of the hotbed from the motherboard to see if it becomes -14 ℃. If the temperature display remains unchanged, it means that the motherboard is the problem. If the temperature becomes -14 ℃, it means the problem of the hotbed
      2> If the temperature shows -14 ℃, it means that the thermistor is not connected to the mainboard, check the wiring, and check whether there is welding in the hotbed welding place.
2. The temperature display is normal, but the temperature does not rise when the heating is turned on
     In this case, the heating bed heating module can be heated
Whether there is the voltage at both ends (about 24v). If there is voltage, it means that the internal circuit of the hotbed board is broken. If there is no voltage, it may be a problem of the motherboard or the heating module.

[davides]

Hi,

The hotbed is working fine, it can reach the desire temperature without any problem.
The problem is in the extruder temperature. In the normal heating state, it shows the same value as room temperature and hotbed sensor. The wiring of the extruder thermistor is firmly connected and seems to be measuring accurately.
The problem is that the extruder cant heat enough.

[William]

Hi, can you take a picture of the motherboard and heating module during heating?

[davides]

Hi,

Here is the photo:

IMG_1095.jpg (415.63 KiB) Viewed 6643 times

I have use a multimeter with temperature function to measure the extruder temperature and the value is the same displayed by the printer.
I have also measured the psu output and it is solid to 24.18V during all the operation.
During the PLA heat hotbed reached temperature quickly, but extruder only reached 172C (It seems it is loosing more power every day).
E0 led was lighted all the procedure (until heating failure appears in the screen)
Hotbed led was lighted until it reached the 60C values (target temperature), and start blinking once it reaches that point.
During heating in the extruder module, the 40mm big fan is on (as always) and the small fan is off.

[William]

Hi，the the motherboard looks OK.
You can disassemble the panel of the hot end and check whether the wiring is in poor contact.
and test whether there is a continuous voltage across the heating rod during heating.

[davides]

Hi,

I have measured the voltage at the heating rod:

The voltage was 24v during all the heating operation in all the three pairs.
I have also checked the connections and everything is fine.
The resistance for each pair is also 25 Ohms.

Measuring temperature near the three hotend connections, I can see that one of them is always 10 degrees over the thermistor value, and the other two are 5/10 degrees below the thermistor temperature. (The hottest part is the one opposite to the fan, so this can be a normal behaviour).

[William]

Hi,
if the heating rod has voltage, it means that the motherboard can successfully transmit voltage through the wire.
This should be the hot end issue. It is recommended that you replace the hot end.