Heat Bed Issue

Hi guys, I have an ormerod 1 at work to play with hooked unto a ramps 1.4 board. In pronterface one of the setting for the bed (PLA i think) is set at 110c. If i click set, the bed slowly heats up, Im talking slowly! It seems to stop at a maximum 65-70c the LED on the ramps and mat is on constant so its calling for power all the time but hits a brick wall of being able to get hotter.
The mat is hooked up to the 11A line on PC PSU whilst the board is on 5A.

Any guidance would be great so i can iron out the bugs 1 by 1.

Cheers

Phil

This is a known issue with some RAMPS boards. Most likely the mosfet, 11A polyfuse, power connector or traces on the RAMPS are getting hot and restricting the voltage to the bed heater. Use a multimeter to compare the voltage from the PSU with the voltage actially reaching the bed heater.

Arduino/RAMPS is a truly awful set up for controlling a 3D printer. Ormerod was designed for Duet electronics.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi dc42, well the ormerod did initially have a duet board- it went pop a while ago from what i got told, so i got hold of a ramps board. So i guess if i probe from 0v to psu/ fuse/ mosfet/bed i can see where volt drop is. I think i can replace the mosfet for a better one, or external so not drawing current through the board, is that likely to help?

Cheers