Megatronics v3 (DRV8825) stepper won't move anymore

First my printer was runnig well, but on the next day I've aborted a print some seconds after it has began to run.

So now I have a big problem i cant' solve.

I've uploaded the testsoftware to the blank Board and all seems to be fine, heating bed and extruder(heat) are Working.
12V and 5V line are OK
VMot at all ports is ~12V

Then i've put one Stepper driver in (testet with new and old ones) , but nothing happens no sound (enable) or movement occors.
But in this Setup even with no Stepper Motor pluged in VMot pulls down to ~3,3 Volt and I don't think this should happend.

I've testet this on all stepper ports with differtent Stepper Driver, but nothings happens (U=12V but Vmot only 3,3V so its not the power supply)

Edited 1 time(s). Last edit at 03/03/2014 02:26PM by ultraflash.

Problem Solved

Diode D3 under the first Stepper Slot was burned out. (But don't know why... underdesigned?? )

Ultraflash,

I'm having the exact same problem with my Megatronics board (v3.0, rev f). Do you remember what diode you used to replace the burnt-out one at D3? I'm unable to open the schematic files from RepRap World, and I can only read a portion of the diode label. It appears to say S1G, and every S1G diode I've found on Mouser.com is a 400V 1A diode. I'm not sure if this is the right value or now.

My printer (a self-sourced Prusa i3) has been running great for over a month now, and died on me just yesterday. After hours and hours of searching, I came across your post. This may be a long shot, but I signed up for this forum just to ask you this question.

Thanks,
Kyle

Well, I think I've fixed this too (for now). I had a few salvaged diodes on hand--I replaced the burnt-out diode with a 400V 2A PTH diode that barely fits, and so far, the printer is working again.

Just having this D3 diode failure on my Megatronics v3.

Its a poor design i think. My motors are 2.8A nema17 and DRV8825 drivers, configured at 1.10v each).

Its two times so far that this diode was burned out. I'm seeking for a diode that support the current and heat the motors and drivers are eating. My selfmade coreXY 3d printer consume arround 5.5Amp

I've routed the solder pins to the exterior by fitting two small cables and solder the diode outside. When printing its at 106ºC almost all the time.

Perhaps BYW29 100 or 200 diode or BY399 are enough powerfull to exchange.

I'm not happy with that board, but there isn't many options to get 2 extruders, sd, screen and thermocouples working on one board.

I put this diode and its hot enough already (102ºC at full load printing)

[es.farnell.com]

Hmm, my v3 isnt doing anytthing but beeps noise and burning ligths when used with test firmware.
I don't even have a d3 diode on my board :s