0 volts to hot bed and hot end from ramps 1.4 -=SOLVED=-

Hey guys I have 0 volts to hot bed from ramps 1.4 with marlin firmware on a new install, all I need it to do is give me 12 volts for my second power supply relay but after I turn it on via pronterface it says on the lcd it is 17c and 110c is not it's goal the ramps 1.4 board is putting out 0 volts where there should be bang bang 12 volts for the heat bed. Anyone know if this is a PWM vs PID thing or have any suggestions? This is my first time configuring marlin and it has been a learning curve so far but not too bad.

Edited 2 time(s). Last edit at 04/20/2015 10:31PM by lunarkingdom.

Do you have power to both inputs?

sure do! Wiring is correct as per this image:

[reprap.org]

Edited 1 time(s). Last edit at 04/19/2015 04:16PM by lunarkingdom.

Does the led come on when you set the heatbed. You mention a relay? Where is that in the setup and what kind? Does your hotend heat up?

This is my hotbed:

[www.ebay.com]

This is my relay:

[www.ebay.com]

I am using a separate power supply for just the hotbed, I have connected the hotbed out from the ramps 1.4 board to the relay but the ramps board does not output any voltage from the hotbed positive and negative, it reads zero on my volt meter, everything else I have gotten working but this, x, y,z and extruder steppers work, I am about to try a hotend to see if it works. I am a noob at setting up the marlin firmware this is my first time so I assume that I as of yet do not grasp how to set up my hotbed in marlin.

Dang, I just tried the hotend, same deal, I read 12.06 volts on both ramps inputs (green plug) and 0 volts on both hotbed and hotend outputs. I have tried activating them in pronterface as well as with the lcd screen controller, they both set the temp to whatever I set it to but the ramps board does not output any voltage.

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cat.farmer
Does the led come on when you set the heatbed/ hotend.?

What's the voltage from the + terminal from either the hot end or heated bed to the - terminal of the main power connectors?

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alan richard

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cat.farmer
Does the led come on when you set the heatbed/ hotend.?

I did not put led's on the hotbed but how many led's light up with 0 volts anyways? There are no led's on the hotend.

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cdru
What's the voltage from the + terminal from either the hot end or heated bed to the - terminal of the main power connectors?

BINGO!

This man deserves a medal, the positive sides of both the hotend and hotbed are working, it is the negative side that does not. Anyone know what to look for on the ramps board if the negative is not working on this connector?

If you have 12V on both the positive rails of the hotend and hotbed, then I would check your ground connection as I would have thought the system has a common ground. If you have a multimeter, turn off all the power to the system and use the continuity function (commonly labelled as the diode checker), it should beep when there is a short. This will allow you to check the ground return.

I have a dumb question, can ground be shorted out? I would think it is more likely a broken trace or cold solder joint, either way if I can not find it it hurts nothing to put a jumper on the backside of the board from where ground comes into the board as long as it will not get into the way of the arduino shield board connections. Either way, I am glad this will be fixed once I work on it this evening after work, thanks guys for all your input!

Ground cannot be shorted out, you do get digital and analog grounds on some circuits and they are isolated for noise, but they will often share a common ground point and you do also have some electronics isolated from others via opto-couplers or transformers, so these would also not share the same ground. Cars generally have their chassis as ground.

I am not familiar with the wiring loom on the printers as new to 3D printing, but if you can post a schematic of your circuit I can give you some pointers where to test. Using the multimeter in continuity mode will easily find most basic wiring faults, just turn the power off or you will get false positives and potentially cause other issues!

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lunarkingdom
This man deserves a medal, the positive sides of both the hotend and hotbed are working, it is the negative side that does not. Anyone know what to look for on the ramps board if the negative is not working on this connector?

RAMPS switches the negative leg. I'd measure for continuity from the - D10 connector to the drain pin, the source pin to the power - connector, and the D10 pin from the Arduino to the gate pin. Make sure all those are good.

The LEDs on the RAMPS board will light up even when there isn't anything attached to D8-D10 but they are turned on. They will indicate that the MOSFET is being switched on and the basic circuit should be working. If the continuity tests out good above and the LEDs don't light, then you have bad MOSFETs most likely. If the LEDs light but you have no continuity, then I'd look at the connectors, traces, or solder joints.

I did not see any led's on the board illuminate when it was on, my stepper motors all work though if that means anything, cold solder joint on the 3 mosfets are suspect then? I will chase it down with the multimeter when I get home in a few hours, thanks!

Got home and took a close look at the mosfets and the big yellow rectangular square fuse things forget what they are called and they had crappy soldering jobs so I reflowed them with a little flux and some solder and BAM all is well in ramps board town ;-) thank you guys for the help!!!!

The 2 red led's are working now too.