Thermal Runaway after changing to round heatbed.SOLVED

I'm getting the following error when I try printing with the bed above 70c.
It heats up ok and then heats up the hotend ok, then goes about 25% through auto bed level and dies.
I have tried changing the temp probe to the one out of my MK2B square bed, the same issue persists.
It is only since I went to the round aluminium heat bed.
I am running latest marlin and ramps 1,4.
[www.ebay.com.au]~



rror:Thermal Runaway, system stopped! Heater_ID: bed
[ERROR] Error:Thermal Runaway, system stopped! Heater_ID: bed

Errorrinter halted. kill() called!
[ERROR] Errorrinter halted. kill() called!

Edited 1 time(s). Last edit at 06/27/2016 05:41AM by Pete75.

Problem solved .. Had to go into config advanced and adjust the thermal protection period from 20 to 30.
* Thermal Protection parameters for the bed
* are like the above for the hotends.
* WATCH_TEMP_BED_PERIOD and WATCH_TEMP_BED_INCREASE are not imlemented now.
*/
#if ENABLED(THERMAL_PROTECTION_BED)
#define THERMAL_PROTECTION_BED_PERIOD 30 // Seconds
#define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius