Major problem, need help asap

Hi all, thanks for your replies, i have good news and bad news, good news is that i was able to borrow a mega 2560 board from a friend of mine and everything worked, the display worked fine under both USB and 12v, it worked for about 30 minutes and then popped with aload of smoke, i disconnected the power and removed the arduino board to discover it had blown a small hole in the larger voltage regulator (the one beside the AC jack), so no back to where we were before, USB power works but as soon as i connect the 12v the display fills with blocks, ive measured the 12v power supply and its kicking out 11.52v, any ideas whats caused it? (please note the only things that were connected were the arduino/ramps 1.4/12v psu and a fan, no driver boards or endstops or steppers)

... could be there's somewhere a near short between +5V and +12V or to GND (maybe a wrecked capacitor?) - so the 'weakest' of the voltage-regulators will blow first

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Viktor
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Hi all, ive tried what shadowram said about removing the diode on the ramps board and powering it from both the USB and the 12v input and its working again, aside from needing the USB being connected all the time are there any downsides to doing it this way? btw im using the gadgets3d lcd ramp w/sd card, i would consider buying another arduino board however seeing how its blown the voltage regulator twice on 2 seperate boards im abit unsure about it

matrix4721 Wrote:
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> Hi all, ive tried what shadowram said about
> removing the diode on the ramps board and powering
> it from both the USB and the 12v input and its
> working again, aside from needing the USB being
> connected all the time are there any downsides to
> doing it this way? btw im using the gadgets3d lcd
> ramp w/sd card, i would consider buying another
> arduino board however seeing how its blown the
> voltage regulator twice on 2 seperate boards im
> abit unsure about it

No there are no downsides other than the need to stay connected to a computer.

Anyone that is using a 24V system absolutely has to remove that diode anyway. (I'm only using 12V but my diode isn't installed, as I'm planning on it staying connected to a computer anyway)

Like I said before, if you really want to run the system off an SD Card without that diode, you just need to supply a clean regulated 5V source down the USB cable.

EDIT: Actually I just thought of something. Have you measured your 12V source? It is 12V and not higher correct?

Edited 4 time(s). Last edit at 05/08/2013 10:05AM by ShadowRam.

Is there a way i can test the diodes? what is diode 2 responsible for? and if its faulty could it cause further damage? i have several new diodes from past projects but is it worth replacing any as the ones that are already attached to the ramps board are new?

Use your multi-meter diode test function.

It should only beep(conduct) in one direction.

You'll have to test the diode when it is not installed on the board.

More Diode Testing information here

Edited 1 time(s). Last edit at 05/08/2013 10:09AM by ShadowRam.

It sounds like you are either getting an external power surge (need a surge protector) or you are encountering a spike in internal resistance for some reason(jammed extruder, faulty or overheating electronic component, mechanical jam.) It is also possible that you have an over voltage on your input which would eventually overheat your vreg over time causing it to fail.