H1 giving erratic reads while printing.

[DocTrucker]

What's the logic behind having a 0.5 duty limit?

As I understand it this is only really useful if the heater responds too quick for the Duet to control it. If the mosfets fail on the 0.5 setting won't happen anyway and the heaters will be locked on 100%. If the thermistor drops out of its hole and gives a false low won't the heater fault detection pick this up quickly?

I did however have it on my mind an age ago to go seriously overpowered and fuse it so if it went 100% it would pop a fuse. Still want to try that. May need a little coil in the circuit to tame the spikes a little, with a corresponding flywheel diode.

[pao_wikhan]

okay its happening again. now im not sure if my duet is broken

[dc42]

@pao_wikhan said in H1 giving erratic reads while printing.:

okay its happening again. now im not sure if my duet is broken

Are you using the thermistor or the PT100 now?

[pao_wikhan]

@dc42
new thermistor, on that pic..
i replaced it with the one included in e3d v6, seems stable so far. but i didnt connect it to the daughter board as its not giving any values.

[pao_wikhan]

if it happens again, i think the heatblock screw holding the sensor is not gripping correctly, but that is a long shot. (my theory that is.)

[DocTrucker]

If you over tightened that it may edge towards occasional shorts. Too loose wouldn't cause spikes like that. That's got to be an electrical or control board issue. I doubt there are real situations survivable for the temp sensor where it could loose heat that quick - even if yanked out of the heater block.

[dc42]

@pao_wikhan said in H1 giving erratic reads while printing.:

@dc42
new thermistor, on that pic..
i replaced it with the one included in e3d v6, seems stable so far. but i didnt connect it to the daughter board as its not giving any values.

If it's a thermistor (not a PT100) then negative-going spikes like that suggest a bad connection, or just possibly static discharge from the hot end metalwork to the thermistor wire. But I think they are too frequent to be static discharge.

[pao_wikhan]

@dc42

well 4hrs into printing, i think the e3d sensor (blue wire) did the trick. odd though cause when i measure the resistance its like 70k-100kohm and not the pt100 value of below 100ohms. its now cleaner than ever. i also replaced the cartridge and moved back to a newer 24V 50W ceramic type with 100% pwm.