problem with hot end and temperature

Hi,in these days im start with very difficoult me 3d printer ultimaker...
now i have a problem with hot end,when im press "print from sd" ,on lcd apare "heating" i have setting 190 for pla(Im not sure is ok) but on the lcd read temperature real and sett (25/190) im look if the real go up,is ok,but is go up the set,it arrive at 230 after go down at 170...the 3d printer game with temperature for more minuts,and the filament go down from nozzle,im move manually the motor of extruder and the filament go out very well,but when the 3d printer stare(if it star but 8/10 not run,it wait "heating" ) the filament not go out of nozzle,im think it return up....

is normal ??
where is the roblem ??
Is possible if my problem is if i not have a fun for hot end ??

my second problem is this:
when it run and print,from the screws of hot end,nozzle,go out little parts of plastic,and it,after few minuts go down on the item now print...

thanks a lot and very sorry for my bad english..
in these day i want make one new hot end,if you what is the best hot end for ultimaker? and what is the best extruder ??

HI Guys, thanks for sharing your time and knowledge, I have struggled in the dark for far to long.
I have a similar problem, on a new corexy build, and one by one overcome issues, now everything works manually, but my problem is heater reaches temperature, the as the print threatens to begin printer, the temperature just drops, and never actually prints anything.
Manually I can get extruder 1 and 2 up to temperature, and they will remain around the set temperature, but when I press print it is happy to get to the required temperature but after this the temperature goes cold, almost like the g-code does a initial warm up then hands over to
a keep it hot routine that is broken.
I even managed to do a M302 cold extrude, to test and see if they are working, and the extruder motors both worked.
Regards Steven

Steven,
Not knowing what electronics you are using, or what firmware... I can just guess to one possibility.

If you have both a hot-end thermistor and a heated bed thermistor defined, and the heated bed thermistor is not connected, then that will cause the firmware to stop the print.

If you have an LCD display then it can tell you if you have a thermistor fault.

Hope that helps.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

Wow Paul you might be onto something here!
1) Arduino, Ramps 1.4, Smart lcd and home made corexy, and I think a good robotics power supply
2) I have tried Marlin, and Repetier firmware, with Prontaface and Repetier software
3) Yes I have both jheads and a hotbed, but I disabled the hot bed in firmware thinking it might be drawing too much power.
Could this be the cause?
4) I had the thermistors swapped and fixed in the firmware, then the extruder motors were swapped, so I just swapped the jumper connectors.
In hindsight could the problem be that only the heaters were swapped? Must I swap all back?
Thanks Steven

HI Paul
I put the hot bed on in the firmware, uploaded the firmware, and tried a 25mm cube print, the extruder heated up until 65 degrees then started cooling off.
I know if I manually heat the extruder it goes all the way up and stays there, it wont do the same in automatic control.
Any ideas?
Thanks Steven

I wish I knew. I'm using Smoothie now so I've been away from Marlin etc for a bit.
I'd suggest posting this under the Printing forum, and attach your config file and a photo of the display when this happens.

Also, could you attach your gcode file? There may be a clue there.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!