RAMPS 1.2 no power

I have a RAMPS 1.2 diy board and an arduino 1280.
Latest Sprinter firmware installded ok, and the pronterface.py connects to "printer".
But the RAMPS board seems not to get the 12V power.
I use an ATX power supply, measured 12V at the socket of ramps, but LED is not lighting neither fan at D9 works.
I have plugged on the RAMPS only the opto-endstops, X axis pololu driver & stepper motor and the fan.
Opto's work but i think the are powered from arduino right?
On the middle MOSfet (Q2) found 11V.

I also measured pololu's voltages and found:
Vdd=0.4V
Vmot=0.1V
EN=4V
MS1=MS2=MS3 = 4.5V
SLP =1.7V
DIR = 0.1V
I don't have any idea right now what to do...

Just a simple question, do i have to connect also thrmistors or even everything in order for RAMPS to work??

some photos

Edited 1 time(s). Last edit at 12/17/2011 12:08PM by cr3a7ure.

cr3a7ure Wrote:
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> I have plugged on the RAMPS only the
> opto-endstops, X axis pololu driver & stepper
> motor and the fan.
> Opto's work but i think the are powered from
> arduino right?

Correct

> On the middle MOSfet (Q2) found 11V.
> I also measured pololu's voltages and found:
> Vdd=0.4V
> Vmot=0.1V
> EN=4V
> MS1=MS2=MS3 = 4.5V
> SLP =1.7V
> DIR = 0.1V
> I don't have any idea right now what to do...

From this it sounds like you have broken traces or bad solder joints on both 12V rail and VCC (5V). I would disconnect the power/USB and remove the shield from your MEGA. Check for continuity between the VMOT pin and your + 12V input pin. It is a pretty short trace between the X driver you are testing on and the fuse.

The VDD pin looks to have a wire run over to the endstop area like it is supposed to. It should be getting 5V there. Follow the wires and solders to find the problem. If you want to post a picture of the back of the board we can look it over.

> Just a simple question, do i have to connect also
> thrmistors or even everything in order for RAMPS
> to work??

The heater control may not function as expected without the thermistors connected, but the motors and fan control should work.

-Johnny

Thanks for your reply, i needed a push to keep up... i corrected a lot of joins on the board.
Now i have 12V on VMOT and 4.5 at VDD on the pololu.

Still nothing, the LED isn't supposed to light up? or it is there for other purpose?

i did some measurements again and found 4.4V at the thermistors' connectors
0V at the resistances just behind them (the blue ones)
As far as the D8-10 i found that +12V through the fuse are ok, but there is a problem with the FETs connected to the pins...
Should i connect a resistor at D10 and one at D8 in order to close the circuit?

Thanks a lot already

No problem, glad you are making progress.

cr3a7ure Wrote:
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> Still nothing, the LED isn't supposed to light up?
> or it is there for other purpose?

The LED is controlled by firmware. In Sprinter the LED turns on when the extruder heater is on.

> As far as the D8-10 i found that +12V through the
> fuse are ok, but there is a problem with the FETs
> connected to the pins...
> Should i connect a resistor at D10 and one at D8
> in order to close the circuit?

I think the 12V you are measuring on D9's screw connector is feeding through the fan. It should turn to 0V if you send the Fan On gcode

M106 S255

D8 and D10 should work similarly, but you will need to add thermistor(s) first.

Can you confirm if your X motor and fan are now working? Also Do you get 0 back for extruder and heated bed if you check temperature?

Fan is working, i gave M106 through pronterface and worked.
Also i get 0 0 for the extruder and bed temps, without connecting anything to those pins (neither thermistors nor resistances)
Endstop status (M119) ok
I changed the x driver's option in firmware to enabled all time, and waited to see if the fan will power on, according to the code but nothing.
playing with g1 but nothing moves

It works! at last... the problem was the joins
Now i have to double check everything on the board to be sure it's ok.
Thanks johnny