Mightyboard fried -> wiring MKS Gen 1.4

[Andreas Engels]

Hello,

i have the great job to bring a Makerbot Replicator 1 back to live. The Mightyboard and the stepper driver are fried, thus i was looking for a 24V compartible mainboard - i found a MKS Gen 1.4.
So far i have succesfully wired X,Y,Z Stepper + endstops and 1 Extruder stepper . However i am stuck right now. 

As firmware i used an old Marlin 1.0. (would be willing to upgrad if recommended). 
Following issues are still present:

1) Thermistor of extruder shows a temp of 354°C (which is definitly wrong)- my guess is that eather Marlins calculatoin is off/wrong or i need to add a resitor- however only wide guesses and i have no idea where to find informations. 

 2) The headbed hase 6 wires (2 thiker once which are red and black - power for the headbead.) and also 4 cabel however the connector on the MKS Gen1.4 allows only 2 cabels...  Any idea?

As you might have guessed i am still working myself into the topic, and if you have sites with information which u can recommend please give them to me. .:-)
 

[Andreas Engels]

I switch the extruder thermistor to an NTC 3950 100k which works like a charm. 

Also i found out how to connect the headbed. however i think i need to make some adjustments.

2 Wires were for heating up (red and black) . Blue is 5V+ and yellow its GND. White is signal and green its GND. However both GND lead to one GND on the headbet. i think i have to add a resistor because the reading it 8°C which it definitly isnt ;).

[Jetguy]

No, you need to REMOVE a resistor to make the heatbed read correctly, OR just tape a thermistor and wires to the underside and move on.

Why? Because the circuit for the heatbed contains a 4.7K pullup.

Your MKS board already has pullup on the thermistor circuit.

2 Pullups is your problem.

The easy way is again, just connect ONLY the thermistor and NOT the additional circuit- use 2 wires instead of all 4.  You would JUST connect white and green to the thermistor input 2 pins of the MKS.

Obviously, red and black are the heater power- you already have that part figured out.

[Andreas Engels]

@jetguy, thanks that did the trick!

hope u have a great weekend