Heatbed Problem

Hi,

I use Ramps 1.4 with Marlin v1.
When i turn on the heatbed, it heats up for a while but randomly just stops heating. No error for maxtemp or something, it's just stops and the led on the Ramps goes off
I tried it with 3 different Ramps, 2 heatbed's and 3 different thermistors but the effect is always the same.
Heats up between 50 - 70 , led goes off and heatbed cools down slowly, i check the voltage output on D8 and it;s 0

Thanks

Could the power supply be cutting out? Is there still 12v going into the ramps?

Hi,

I found the issue, once I add an Fan on top of the Ramps board it working fine, seems like that the heatbed pulls a lot of power and the thermal fuse kicks in.

Hope this post will help any1 in the future

This is why my heatbeds are connected to the ramps via SSR

Brian

I take it that the heater control is ON/OFF and NOT PWM.
I guess I can run my heater on AC off of a suitable stepdown transformer and switch the primary with a solid state optically issolated relay?

You need to confirm that the heatbed is set up in firmware to run bang-bang. Some firmware still has the heatbed set up for PWM by default.