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Dec 2015
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Dec 2015
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Datcu_Bogdan_Al
Dec '15

Since you guys helped me with my previous problem maybe someone can help me with a probably worse one. i had my prusa i3 with a megatronics v3.0 connected and working (still needed a bit of tuning but it did print several calibration cubes) and one night i shut it off and unplugged it. Next evening i plug it in and the motors and heating stopped working. nothing changed from the previous night hardware or software and the printer connected with no errors to my pc. i tested to psu and it works fine but to be sure i replaced it with a new one that also worked and still same result. no motors heating or even the hot end fan which used to be the first to turn on. i don’t have the tools to check the current but i have used some 12v led strips to check and on both the hot bed input and normal input contact with the screws made them light up. on the other hand the hotbed output and basically all the other outputs nothing. tried all the termistor ones and the lcd output and nothing.

the board doesnt seem damaged in any way. there was no smoke or sparks or anything when i turned it on and it didnt work. if powered from usb it connects with no errors (does not connect at all if i switch the jumper to psu power only). maybe something randomly fried when i plugged it in that evening or when i unplugged it the previous one but i have a hard time believing it as there is no signs of dmg. the board looks and smells like a brand new one but i admit i am far from an expert on electronics and short circuits.

hoping someone has some insights before i take it to a repair shop or even worse, replace it.

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    Dec '15

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    Dec '15
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Clement_1
Dec '15

Seems to me like your “power” side of the board is not connected, or powered.
You’re telling us it doesn’t connect to the computer when you use the “psu power only” jumper, so this looks like it’s coherent.

I suggest you inspect your board for the 12V power rails (or 24V depending on what your psu outputs). If you have a multimeter, you can measure the voltage on several components, and unless you touch 2 pins of a component with the same metal part, you don’t risk to shortcut anything in voltmeter mode.

With no power on the board you can also check the conductivity of the two orange fuses (the 2 big vertical squares). If they burnt to protect the board, then they probably cut power to the whole board.

Datcu_Bogdan_Al
Dec '15

thnx. going to order a multimeter check it out. but what replaces the 2 orange squares on the megatronivs v3? i remember the ramps 1.4 i had had them but the megatronics i have doesnt (uses something else i assume). this is what it looks like for refference http://reprap.org/wiki/Megatronics\_3.0

Datcu_Bogdan_Al
Dec '15

ok so i got my multimeter. and i have measured voltage in a few places but i do not know if the values are what they are supposed to be. for the heated bed output it’s 1.85v, each of the extruder heaters are 0.51v, the end stops are showing 5v, the thermistors are showing 5v, the motors i am not sure which pins to use to measure but they are all either 0.002 or 0.004. i have also checked conductivity between power input and the out hole for the motors on the board, and thermocouple and the endstops and they all give a signal. not sure how the fuses look on this board. tried to google it but found no indication.