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View Full Version : Need Help! Heatbed and extruder won't heat



stargeezer
07-11-2015, 01:41 PM
After building 10 printers for friends and family I've ran into a problem I've not seen before. When I turn on either hot end or bed I see the spike on the ponterface display showing and within a second or two the graph flatlines. A check of the voltages indicates 0 vdc.at the hot end and bed connectors, but full voltage at the power supply connectors. So far I've swapped out the Mega and the Ramps boards and the power supplies. The firmware is the same as I'm running on other printers including my own.

Anybody have any suggestions?

123CNC
07-11-2015, 11:56 PM
I'm not sure with Pronterface, I more familiar with Repetier, but they all share a lot of the same functionality. Yes, verify your power supply first, I suspect both your Mega and RAMPS boards are fine. Check the voltage when you first start the control, see if you see a voltage spike at the bed or print head heater before they shutoff. I've seen many times that if you are trying to operate either the bed or hot end near their upper limits, that their is a hard code high limit threshold that will likely be surpassed with the peak and immediately shutoff your two heater outputs. You can try to go into your printers machine control software and change or increase that threshold or manually sneak up on the values you are trying to reach. Say 15 to 20 degrees below target and than changing setpoint by half the difference after you witness a stable control. usually 1 overshoot and then stable deviation in 2 to 3 cycles.

stargeezer
07-12-2015, 02:46 PM
Thanks 123CNC. I'll check the firmware tonight. After I saw your post, I uploaded the firmware I used to another working printer and promptly had the same issues. Now I've got 2 deadlined printers. :) I guess I must have overwritten my files with some "alien" firmware. I hope I can find the working copy in my backups.

I have been considering making the jump to Repetier. I have looked at it a couple times but have hesitated to change horses mid-stream. Perhaps while things are a bit jumbled, it's time to go. Any advice about a good tutorial?

123CNC
07-12-2015, 04:10 PM
If you like Pronterface (or Printrun), no clear reason to change. No tutorial suggestions on Repetier, just poke around, you'll find it very similar. I would stick with whichever you are most comfortable and get good prints with.

As previously mentioned, you could use the Arduino IDE to modify the temperature shutoff thresholds in the firmware. Or at least test to see if this is your issue by making sure your bed and hot-end temperatures are a good 20- 25 C below the upper limits. Looks like Pronterface has graphing for the temperatures and related outputs similar to Repetier. Have it open and running when you test lower setpoints to confirm if you can avoid the automatic shutdown. The graph will aid in viewing the overshoot, which is usually much greater if you are starting out cold.