Bed temperature only gets to 34.5°C

Simple as that, the bed only heats up to 34.5°C, far short of the required 50.

Everything else seems to be working fine and I managed to print one thing by lowering the required temperature but the first few layers were awful.

Any Ideas?

I did a “paper like” tape on top of the heating bed. Then the PLA will stick far better. (This is nowhere stated in the official documentation, but often other printer has something like this.)

Make sure wiring is ok.
Bed used wires in parallel, due to elevated currents.
If there is a wiring problem, series resistance of the wires may be too high, so that current will be to low, hence the low temperature. Try measuring the voltage that arrives at the bed.

[quote=“VEL417”]Make sure wiring is ok.
Bed used wires in parallel, due to elevated currents.
If there is a wiring problem, series resistance of the wires may be too high, so that current will be to low, hence the low temperature. Try measuring the voltage that arrives at the bed.[/quote]

I’m measuring the voltage across the bed at 15v.

Interestingly when I connected to it today repetier told me it was at 3.9°C and my house isn’t that cold. I heated the bed to 25°C and personally measured the temperature with a laser thermometer at 55°C, so I presume the thermistor isn’t working properly.

The only thing I had was masking tape but it worked brilliantly, so thank you.

Repetier doesn’t even recognise the print bed now, there’s no temperature on the screen and I can’t heat it manually.

OK, I’ve done a few checks now. The wiring is fine, voltages and resistance are almost the same between the bed thermistor and the extruder thermistor.

And the “bed” temperature shows up on Repetier when I swap the wires for the two thermistors.

So, I’m not sure what to think now, any ideas?

measure the ntc at extruder and ntx on the bed directly.
and make that the ntc from the extruder the 2 wires doesnt make contact with each other of the extruder.
If they don’t measure the ohm they have to be then there’s the problem and they are broken.

[quote=“Citystars”]measure the ntc at extruder and ntx on the bed directly.
and make that the ntc from the extruder the 2 wires doesnt make contact with each other of the extruder.
If they don’t measure the ohm they have to be then there’s the problem and they are broken.[/quote]

Both the extruder thermistor and the bed thermistor measure the same resistance and the extruder one works perfectly.

did you tape a bit under the bed, blue tape is a bit conductive, maybe it shorts the curcuit and gives a signal of 34.5 degrees?

Nope, just masking tape and only on the top.

And besides, it doesn’t read any temperature now.