Heating problem when printing from SD

Hi

I've been having some trouble to print from SD.

When I try to print from SD, or even set the nozzle temperature from the RAMPS menu - the nozzle temperature can't get to stabilize and the temperature jump 4-5 and sometimes even 10 degrees from a reading to the next reading.

I thought it was a matter of PID setting, but when I tried to set it with USB cable, the temperature rises perfect and very stable.
That rules out hardware problems as well.

The problem only accurs when I'm printing standalone - with no PC connection.

Anyone experienced such problem before? Any ideas?

First, look at the gcode on the SD card and make sure it looks OK. Next, format that SD card and put a fresh copy of the gcode on it and try again. If that doesn't work, try a different, freshly formatted SD card. Make sure you eject the SD card from the computer before you physically pull it out of the computer.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

The problem also happen the same way when I try to heat things up through the ramps menu.
Even with no SD card at all.

So I think the SD card is innocent

Little bit more details. Might help for solution

I tried to warm the extruder with USB connected, then, when it is warm enough, switch to standalone mode and print from SD.

When I turned on the system (after the extruder already warm), I noticed the nozzle temperature is very not stable.
Even without trying to heat the nozzle. Just reading the temperature.

When it was connected with USB, the temperature was very stable.

I can't understand what might cause such behavior

Check the 5V regulator on the controller board.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Might be the something to do with it. I'll check it tomorrow.

I did some modifications lately in the 5v area.

What made you think of it?

An update-

The arduino was powered from the PSU (PC PSU).

I power it now with external 9v PSU and everything works perfectly smooth.

It seems that it was a matter of power consumption.
Thanks for the tip