Hot end not heating up Ramps 1.4

I recently changed my hot end due to a faulty wire,when I put the new one in it worked but my temps were way out of range,I shut it down and re powered.When I powered it up the hot end no longer heated up so I changed the heat cartridge and thermistor(still no good).I noticed that I have voltage when I pull the leads from the board feeding the hotend and when I wire them back up I get 0 volts.did I blow my board?

Check the voltage between power supply ground (the power input terminal) on 5A) and D8+ , you should see ~12v. If the hotend is switched off, you should also see ~12v at D8-
Switch the hotend on. D8- should now show 0v. If it still shows 12v, then the mosfet may be blown (or board trace damaged) or your Arduino is not enabling it for some reason.

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Waitaki 3D Printer

I have 12v on the input rail to ramps card,d8 shows no voltage.I ordered an additional ramps and have the same results.Is it my settings?

D8 is normally for the heated bed and D10 is for EXT0 Hotend, Worth checking?

Doug

I work with RAMPS 1.4 at a very experimental printer and use my own very easy firmware to control it. Which PIN is assigned to D10 and D8 of the RAMPS?
Marlin says "-1" which I don't understand.
I thought it must be PIN 8 (Bed) and PIN 10 (Hotend), as PIN 9 works for me as contolling of the FAN...
Sorry for asking here, but maybe this also helps Munson...

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derletztename
I work with RAMPS 1.4 at a very experimental printer and use my own very easy firmware to control it. Which PIN is assigned to D10 and D8 of the RAMPS?

D8 and D10 as labeled on the RAMPS are digital pins 8 and 10 on the MEGA 2560 controller.

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Marlin says "-1" which I don't understand.

-1 indicates that it's not used/not configured. Are you sure you're looking at the correct configuration for a RAMPS-based controller?

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dougal1957
D8 is normally for the heated bed and D10 is for EXT0 Hotend, Worth checking?

Doug

Oops, yes of course Doug - that's the 2nd time I've referred to the hot-end o/p as D8!

Munson- check your voltages again as I mentioned previously but D10 this time.

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Waitaki 3D Printer

D10 has voltage on it when I click heat extruder in repetier only when the leads to the hot end are disconnected once I screw the leads down the voltage goes to 0v. I have tried 3 hotends(ubis and Anubis)

Thank you for your help I think I found the root cause.The original ubis had a broken wire so I switched it with the cheaper Anubis which caused the voltage to shut down on D10 when I heated up the hot end so I ordered another heat cartridge for the Anubis that caused the same problem.So I took the only good UBIS that was on another printer and now it works.I originally changed the board,so now I have to tweak the pots for the motors.
I plugged the heater cartridge directly into 12v and it heated up quickly so I assume the Anubis cartridges draw too much current so the board shuts D10 down,maybe I can hook up a relay to controll the heat.

When I heat up the thermistor by grabbing it and raising the temperature using my body heat the extruder heats up no problem

Hi, there, I've working on my RAMPS 1.4 and had the similar problem. The voltage across D10 is 12v and the hot end works properly, but the voltage across D8 is 7mv and the printbed is not heating.
So is there any problems on the board or in my Arduino programming?
My voltage source is 12V 5A.
Thanks for reading!

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DIPtheRipper
Hi, there, I've working on my RAMPS 1.4 and had the similar problem. The voltage across D10 is 12v and the hot end works properly, but the voltage across D8 is 7mv and the printbed is not heating.
So is there any problems on the board or in my Arduino programming?
My voltage source is 12V 5A.

D8 gets it's power from the 2nd input connector next right below it. You say that your voltage source is 12V 5A which is the other power input that powers everything except D8 which is typically only the heated bed, the highest current drawing device by far. If you don't have anything plugged into the 2nd power input, you won't get anything on D8.

I just replaced my Gen6 electronics with a RAMPS setup. I have everything except the heater for the hotend working. My X, Y, Z, and E all move in the correct directions and the correct amount of travel. My termistor reads the correct temperature.

I checked the voltages from gound to the + and - sides of the D8 connector. They both read around 12 V with the heater on or off, makes no difference. So if they are both at +12V, there will be no current flowing through the heater.

I see other people mentioned a faulty or incorrectly installed MOSFET. How can I tell if it's installed correctly?

BTW, I'm using a J-head with a 5.6 ohm resistor for the heater. If I disconnect the heater wires from D8 and measure the resistance with a meter it reads correctly. It's not a blown resistor/heater or faulty wiring.

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3D Printer: Reprap Original Mendel with RAMPS 1.4 electronics, j-head MK V-BV 0.4MM extruder, Wade's geared extruder, setup for 1.75MM filament

I did some more research and found pictures of how the MOSFETs are supposed to be soldered to the board. My MOSFETs look correct. I then did some measurements to see if I thought the hotend MOSFET was bad. When I use a meter to measure the voltage on the gate of the MOSFET, it only reads 100 mv. I would have expected it to read around 5 V as it should be trying to turn the MOSFET on full to heat up.

Is it possible that I have a configuration wrong in my firmware? I have not made any changes to the pins.h file. From what I can see, the hotend should be driven by pin D8 of the Arduino Mega2650. When I measure the voltage directly on the Arduino D8 pin it reads the same as the gate on the MOSFET.

I'll attach my config files if someone sees something wrong.

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3D Printer: Reprap Original Mendel with RAMPS 1.4 electronics, j-head MK V-BV 0.4MM extruder, Wade's geared extruder, setup for 1.75MM filament

It's really best to start your own threads rather than replying to someone else's thread that really doesn't have anything to do with your issue.

What are you using as a ground point when you're measuring the voltage from the D8 pin?

I found the issue. I had to choose motherboard type 33 instead of 35.

ramps not enabling d8,d9,d10 ports from repetier firmware.there is no voltage at these three ports. after verifying my repetier firmware still not able to figure it out. also the MOSFET's are working properly. any help would be appreciated.

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anujpri
ramps not enabling d8,d9,d10 ports from repetier firmware.there is no voltage at these three ports. after verifying my repetier firmware still not able to figure it out. also the MOSFET's are working properly. any help would be appreciated.

Did you ever figure out what was going on with yours? I'm having the same issue. Thanks!

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EmailGuy
I found the issue. I had to choose motherboard type 33 instead of 35.

Thanks had the same issue.

My hotend stopped heating, and i did as you said.
When hotend is switched on, the d10 - stays 12v

maybe my mosfet fried
how do i check if it is damaged? and what are its specs, in case i need to buy one and replace