Unresolved Bed doesn't heat

Hi to all.

I print with my RoBo3D since one month. I print with PLA & ABS.

Heated bed reached up to 105°C without problems. But this evening the heated bed stopped heating.

I tried to unplug the printer, and also I checked under the glass and the Arduino Board, but it seems to be all ok.

I post some pics, mybe you could help me

 

If you updated the firmware you are capped at 85C.

 

To clarify, 85C will trigger a shut off so the highest practical setting would be 82C with 80C being the safest.

It looks like you are missing a polyfuse on your board.

 

Did you do any modifications? Did you remove the connector clip before running it at 105?

 

Hi to all and thanks for the time.

I didn't update anything manually, but if it is automatic maybe could be updated.

The problem is that the bed doesn'r heat at all, also for reach 30 degrees C.

I didn't modified anything: the printer arrived at home and I just printed With different temperatures of the bed (105 is the maximum the I set).

I am a bit disappointed but I hope to fix this problem.

Thanks

 

Does the bed thermistor read a temperature at all? It should output room temperature when you turn the machine on. If it shows 0.0 you likely have a bad thermistor or thermistor wiring/connection which would prevent the bed from heating.

 

The thermistor read correctly the room temperature while not printing. Also during the print it reports the growing temperature (with PLA it reports up to 37°C).

 

So it heats up some and then shuts off? Any idea what temperature / how long it takes for this to happen?

The polyfuse is probably heating up and tripping and by the time you restart things it has reset. Now you could just put a fan on the polyfuse, but that is not the best way to rectify the situation. There has to be a short that happens somewhere in the heated bed circuit or your polyfuse is simply fouled up.

Could replace the polyfuse with a replaceable fuse or a circuit breaker.

Some background on polyfuses.
http://engineering.electrical-equipment.org/electrical-distribution/polyfuse-circuit-breakers.html

 

I explained bad.

The thermistor records the temperature change due to the heat of the printed material: the bed is not heated never on my command. I just wanted to further demonstrate that records the temperature correctly.

 

If you have a multimeter I would start testing continuity along the circuit. Start with the heating element itself and work your way back to the circuit boards.

 

Thank you, you are very kind. I will carry out the operations that you have shown me, hoping to get to a solution. (how sad)

 

Who did you buy this printer from? There's a couple red flags I'm seeing that are giving me cause for concern.

Look at the connector on the bed, see if there's any burnt marks.

The polyfuse on his Ramps board has been replaced by a jumper of some sorts.

 

I bought the printer from a dealer in Italy. Obviously I also asked him how to fix the problem, but rather understand it alone (hoping to succeed, even considering the expense).

 

That jumper on the polyfuse is giving me cause for concerns. I suggest you try and return it to him.