> They changed the MOSFET to SMT versions capable of 76A drain current.
This means nothing. The issue is not how much current can the mosfet handle, but rather how much heat it dissipates doing that. You need a mosfet with a very low Rdson.
But more than heat dissipation on the mosfet, I'd be concerned with the traces on the sanguino. You can easily find a mosfet with <=2mOhm Rdson that can drive your load with no or very little heatsinking. But I doubt the traces on the motherboard were designed to handle this current.
My suggestion would be to make an external board to drive the heatbed, something as simple as the attached schematic. You can make this on a perf board, costs about $3, and can drive the load from an extra pin without destroying your sanguino.
This means nothing. The issue is not how much current can the mosfet handle, but rather how much heat it dissipates doing that. You need a mosfet with a very low Rdson.
But more than heat dissipation on the mosfet, I'd be concerned with the traces on the sanguino. You can easily find a mosfet with <=2mOhm Rdson that can drive your load with no or very little heatsinking. But I doubt the traces on the motherboard were designed to handle this current.
My suggestion would be to make an external board to drive the heatbed, something as simple as the attached schematic. You can make this on a perf board, costs about $3, and can drive the load from an extra pin without destroying your sanguino.