Hot end temperature problem

Hi,
My first post on the forum, so far I've been troubleshooting things myself and been fixing problems but recently for no reason when I am printing the temperature suddenly drops to about 120-140 for no reason. I've gone through the gcode just incase something was getting put in and I can't see anything on there. Thing is it used to work fine and then this problem just randomly started happening. I have noticed though on pronterface under the hot end temperatures for some reason there is 140 degrees as a setting, don't know how or why it is there.
Any help or advice would be appreciated.

You are able to manually put in whatever temp you want in Pronterface (which you may have done accidentally?), but the defaults are 185 and 230. Anything you put in there will stay there unless you restart Pronterface - which will erase the manual settings and just leave the defaults. There are also temp settings in Slic3r (Filament tab) although I set mine to zero to manually control the heaters. Not to sure though what exactly is happening at your end.

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Waitaki 3D Printer

Thanks for replying, basically I print from the sdcard because I loose connection easily via usb so just use pronterface to monitor the temperatures and movements of the print. When I press print from sd card everything works fine as in the bed and hotend temperatures go to what I set it up as and the during the print the temperature just drops as if the heating element has been shut off. I try to manually correct the temperatures when printing but pronterface doesn't seem to control the printing until about 20-30seconds after I press pause or set temperatures by which point the print is usually damaged. I have tried resetting the board and uninstalling and reinstalling drivers and software but no luck.

OK I think I may have found the problem, I think its the 6 wire connection, just that may have a loose connection in it either the male or the female, will have to give it another go at rewiring it and see what happens but I have a feeling it might be this.
Will report back once I've had a go at it!

You don't mention what type of board and power supply you are using. Three thoughts come to mind here:
1. You have a loose connection from the board to the heater that is disconnecting.
2. You have a loose connection from the board to the heater that is overloading the powersupply (the
loose connection can cause excessive amps to be drawn).
3. The MOSFET on your board is going bad.

Also, is there a chance MAXTEMP got triggered? Any errors in the log?

Hi,
Sorry I forgot to mention those, I'm using mono mendel with a melzi v2.0 board. I've found the problem and fixed it! It was the 6 wire connection just above the extruder, I even felt it and it was really hot! I recently printed a tall print and I think I hadn't fully seated the wires in the switch so it have become loose and lost connection when it was moving. But all fixed and working well again!
Thanks for your help guys really appreciate it! I'll try make sure I put everything down in detail if I get any other problems so it's easier to work out.
Hopefully this will help other people as well!