Unresolved Bed not heating

I don't know what is up I've already contacted ROBO about another issue but I thought that I'd check here on this one first. So as the title says, my bed isn't heating does anyone have any ideas as to why not.

 

Does it report a temperature? Is the connector lose? Is there damage to the ramp board?

 

In order of questions, yes, no, no. I have also felt the bed itself & it is cold as a normal piece of glass.

 

When you enable power to the bed does the D8 LED light up?

 

Yeah the LED's light up & the fans start up like normal, but when I tell the bed to heat up it doesn't do anything @ all.

 

It's an LED on the ramps board. It's probably green:


Where it says D10, D9, D8 on the board if you look to the right of that there's Q3, to the right of that is 3 solder pads, one of those is the D8 LED that indicators there's 12v to the bed.

You could also measure with a multimeter on the 11A terminal of the connector to see if there's 12v coming in. Though I'm guessing you may not have a multimeter.

 

This is what I have when I turn it on, I'm not sure if that is all of the LEDs that are supposed to be on or not so I figured showing you would be a good idea.

 

That's correct yes.

So we know the electronics is working. Next step is following the wire from D8 to the bed and see where the disconnect is

 

I made sure all the connections are connected properly & now it won't go past 26 on bed temp, it's like it gets up to it & then it drops down & then hovers around 25.3 or so, this is really annoying 'cause I can't afford to blow $90 on a new bed.

 

A multimeter is like 5 bucks. Use it to measure wire continuity

 

Mark
When you do the continuity test what reading should you be seeing from the bed. Do you set the multimeter to ohms, then just check what resistance you get back from the bed.

 

Mark, I disconnect the wire from the heated bed and from the ramps card. I then checked the wire from the connector on the heated bed back to the ramps card with a multimeter, and found no short or other problems. I then check the wires going into the heated bed, show about 1.2 to 1.4 ohms, does this sound correct? I check both the thermistor wires and the heater wirers and they do not show any problems.

I have burn out 2 mosfet on ramps cards trying bring up the temp on the bed to 40-60C, no higher. This is my last Ramps card and I don't want to blow out the mosfet.

Is there some way I can check out the Ramps card heater output and check to see if the thermistor is working without blowing out the mosfet.

 

Mark
Thanks for the suggestions, I will give them a try.

 

This happened to me too, check that there is no broken wire between the bed and the board. With the movement pf the bed, I had a wire break inside the insulation, hard to see.