Heatbed used to work.

I have a delta printer with a silicone heatbed which is clamped down with a glass plate. It work a time and all of a sudden it stopped working. I have tried to redo the wires to make sure the connections are more secure and cleaner to no avail.

I just want to list something to be clear.

Heatbed is enabled in marlin
Headbed temp sensor is connected to board next to hot end thermistor
On the powerblock on the ramps I have 12v power going to both terminals as listed on this diagram. [www.nextdayreprap.co.uk]
Heat bed is wired to D8 next to the mains power block.
I get continuity across the heatbed terminals.

Is there anything on the board that may have failed that would prevent the heatbed from turning on?

Are you using host software? Does it show a temperature from the bed thermistor or does it show 0 or have some sort of error message such as "error MINTEMP"? If the temperature reading shows up and is reasonable (not 150C or similar nonsense), the bed heater should work. You may have let the smoke out of the MOSFET that switches power to the bed heater.

There's an LED on the board that indicates the status of the MOSFET. The LED is on the output side of the MOSFET, essentially parallel to the bed heater. If the LED turns on and off when you turn bed heat on and off via the console, there's a wiring problem.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I am using the host software. The temp does show and I do see it moving slightly if I cover it with my finger. I'm not 100% sure which LED you are referencing. Is it the one or the right of D9 in this picture?

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I dont think I see the LED turn on at all. All I see is the LED on the Arduino Board turn on.

Say the wiring is fine. How do I troubleshoot some more? BTW I have ordered a Keenovo standalone controller for the heat bed but that wont be here for about a month. I would rather it be independent anyways but I would still like it working as it stands.

The LED is on the heated bed, usually it is placed right where the wires connect to it.
If you see the correct room temp and it changes when you heat the sensor than that part should be fine.
Leaves the question if you actually get power to the heated bed at all.
You could simply connect it directly to power, this should make it heat up fast and the LED on the bed should go on as well.
Other way would be to measure the voltage with a multimeter during the heat up when there is no PWM active.
If the bed heat fine when connected directly to power but not on the controller you could have a blow mosfet preventing the power to reach the bed.
If there is a LED indicating the bed is heating on the controller or Arduino than the mosfet is blown for sure.
Q1 to Q3 are the mosfets on the Ramps board, you can do a basic check if they are ok with a multimeter, procedure is simple.
Ask Google for how to check a mosfet with a multimeter and you agree
Hard part is to solder them out for checking and replacing.

If I have to replace the mofset which one do you recommend? I read that NTE2986 is he standard one

I watched this video and learned a few things but it made my head hurt. [www.youtube.com]

You either test the mosfets or follow the traces on the circuit board from the heater connection to the offending mosfet.

I was referring to LED2 on the RAMPS board right next to the D8 MOSFET (Q3). If you turn on the extruder heater, you'll see an LED a the corner of the board flickering as the extruder gets up to the set temperature. Does the LED next to D8 MOSFET light up at all? If not, the Q3 MOSFET is probably dead.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]