Heat Bed issues

[tassat01]

Hi everyone, hopefully someone can give some insight for a problem im experiencing. The heat bed when heating up will continue to heat up with the thermocouple showing the same temperature ie 12/70 can someone tell me where I need to look as the unit is only 6weeks old.

[William]

Hi, do you mean that the hotbed is heating up continuously, exceeding the temperature required for heating? You can try to unplug the hotbed line from the motherboard to see how the Lcd display is displayed. If the display temperature is negative then the motherboard has no problem, you can also measure the thermistor of the hotbed.

[tassat01]

When I go to heat up the bed the red LED under the bed is on and its heating up, but on the display is the current temperature and desired heating temperature. The bed is showing a desired temp of 70c but the other actual temperature shows 11-12c. So im assuming that is it doesn't turn the bed off cause it doesn't know what the temperature is it will continue to heat up.

[William]

Hi, You can 1. Check if the hot bed line is fully connected to the motherboard;
            2. Unplug the hot bed line and check the hot bed display displayed on the LCD screen. If the display is negative, there is no problem with the motherboard.
            3. Measure the resistance of the hot bed.
I hope this can help you.

[tassat01]

2 photos are attached. If the thermocouple is open it won't detect but the bed still heats, I'm sure this is cause the thermal runaway isn't on. Does anyone know the type thermocouple on the heatboard. Looks like that needs to me replaced.

[William]

Hi, You can 1. Check if your hot bed line is bent into the motherboard;
             2. Use a multimeter to measure the resistance of the hot bed when not energized. The normal range is about 80kΩ.

[tassat01]

Hi there, after finally getting some new thermistors. And double checked it and reconnected to the board to no avail. I checked it with my multimeter both at the connection and the plug. When heating the bed it still shows 11/70 and the bed heats up but the temperature isn't increasing. Is there anything else that can be checked or should I just replace the board. I want to get my printer up and running, it hasn't been used for a while cause where I am it always takes 10days minimum for parts to come to me.

[William]

Hi, Do you mean that after you turn on the printer,
the hotbed shows that the temperature is not correct
and the previous state is maintained after replacing the thermistor?

The hotbed is heated but the temperature display is constant?
You may need to replace the motherboard.