RAMPS board smoking

[thegman]

On the past weekend, after patiently waiting for over a month, I received my replacement parts for my Prusa I3A. A set of A4988 and one of the x-axis plastic parts. I put everything together and started to print. Everything was working fine, I printed some items successfully.

Now something has gone very wrong. I started to smell some electronic parts burning, then I saw some smoke coming from the RAMPS board. I immediately turned off the printer. I used my IR thermometer to check the temperature on the RAMPS board and saw that one of the MOSFET components was very hot. It is the one for the Heatbed.

I let it cool down. and check all the wiring, everything is fine. The printer had been working for a couple of days.

When I turned the power on again, without out it being connected to the computer, I saw the red LED for the heatbed come on and the temperature displayed on the LCD starts to go up. The temperature for the MOSFET also started rises rapidly and I could smell burning electronics again.

I can see that there is heat fatigue on the MOSFET. picture attached.
https://drive.google.com/file/d/0B8FwZ8 ... sp=sharing


I also attached a video of me turning on the printer and monitoring the temperature on the LCD panel and using my IR thermometer to see the temperature on the RAMPS board to climb over 100C.
https://drive.google.com/file/d/0B8FwZ8 ... sp=sharing

Looks like there are more faulty components with my printer that I bought.

I was very patient before, but now that I have used my printer and made a few things, I am very excited to do more and now this happens.

Please resolve this immediately, as I have not been able to use my printer until now and I ordered it in February!!!

[zhangxueyou]

The fan beside the mainboard is used to cool down the MOSFET. You reverse the mainboard and the wind is blocked by LDC connectors. That will influence the MOSFET to cool down.

[thegman]

If I flip the board around 180 degrees, how do I wire in the power supply and the USB port? There is not enough space between the frame and fan and board to plug in the connectors.

The wiki page does not show how to mount the RAMPS board. It only has the photo of the Sanguinololu board mounted. The Sanguinololu board looks smaller so there is space for the power to connect and the USB connector is on top when mounted. See http://www.geeetech.com/wiki/index.php/ ... side_panel.
The photos at the bottom of the page do not show RAMPS board.

Also, why is the heatbed coming on when I turn on the printer? I am not printing anything and have not set the heatbed to start heating. The computer is not even connected.

[thegman]

Here is a photo of the other side of the MOSFET. It has melted and burnt the plastic.

The thermal fuses on this board do not work.

If I wasn't in the room at the time of this incident, who knows what would have happened?

[zhangxueyou]

Hi, thegman
Please check your private message.

[Joseph]

I need help on this issue too.

Mi printer made the same thing look!!
https://www.dropbox.com/s/9ayskd0wre5v5 ... 2.jpg?dl=0

Please i recieved the printer 1 month and is the first time i get it after a lot of issue of missing part and being send the wrong firmware.

[zhangxueyou]

The mainboard should be mounted on acrylic board like this picture, so that the fan can cool the MOSFET down.

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