wiring xbox PSU+relay+RAMPS 1.4

Hello everybody,
I bought a reprap kit two weeks ago composed by all the mechanics fully assembled, an arduino Mega 2560, a RAMPS 1.4 shield and a XBOX PSU 203W and a relay. I have some little experience with arduinos and electronics but it's the first time I have to work with a relay... I connected everything according to the documentation furnished by the seller but I'm not sure at all that's correct, the documentation I received is not enough detailed (for me... ). I'm able to upload to arduino only when the RAMPS 1.4 shield is removed. When I connect the RAMPS, it's impossible, arduino tells me the com port is already in use.Actually I would like to be sure of my connections and the fact that I have to remove RAMPS shield to be able to upload to my arduino is not a good thing I guess...:/
I joined the documentation I received and the plan to show you how I connected things..
Thanx to take look... I can't wait to print things O_o
Regards
Manu

I would start by disconnecting everything from the ramps.. drivers and power, so you have just a bare ramps board. Then try to connect. If that works, then add the power and try to connect. Keep adding componts until it fails. Just shut off the power each time before you add anything to the ramps board.
Did you happen to connect the power backwords at some point?
Also i'm not sure you need the relay with the ramps board, not a bad feature to help not desroy things, but the heatboard could be connected to the ramps directly. I'm sure someone will correct me if I'm wrong.

hi,
thanx for the reply ...okay, I disconnected everything from the ramps, I try to upload to arduino----> it doesn't upload [avrdude: stk500_2R_ReceiveMessage() : timeout]. I removed the ramps----> I can upload to arduino .... :/
What do you mean by the power "backwards"?
ok, good to know about the relay...

if you have everything off the Ramps board and no power applied to it then the Ramps board is bad. check D2 to see if it is shorted, ohm meter should read one way but not the other.
by backwords I mean negitive to positve - positive to negitve

ok, thank you, I'm going to contact my seller..
hmmm, before that, I'm going to check what you said with the Ohm meter...but what is D2, and how to know if it's shorted...(sorry, newbie here)

D2 is the diode that sits behind the fuses.
ohm meter should read one way but not the other.

[reprap.org]

hi,
sorry not to have responded earlier, I was quite busy on other stuffs, and finally decided to order a new RAMPS 1.4 , and with this new one it connects perfectly ... one problem resolved. Now, the only last problem (for the moment ) is the relay.. I know you said it can work without, but because I bought it and it was tested with, I would like to use it anyway. So, if you or anybody else could watch the attached file and tell me if how I connected the relay and the xbox PSU is the right way, it would be great ... and maybe soon I'll be a printer
Thanx
manu

Wiring looks ok, but make sure to double up the wiring from the PSU to the relay (yellow to 30).

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It looks like it is connected correctly. Do you hear the relay click when you turn on the heatbed? If not make sure you are getting 12volts at D8. If so then check that you have 12 volts on the relay going to the heatbed. You can also disconnect the heatbead, turn on to enable the relay and check the contacts, with an ohm meter, there should be no resistance, turn off the heatbed and you should have an open circuit.

thanx bobc, thanks cat.farmer,
I doubled up the yellow wire to the relay, and when I turn on the heatbed I can hear the click and it perfectly works ... it even turns on my beautiful red led ...by the way, the leds which turns on is upside, but I have another led downside (of the heatbed), what is its function? ... so now I have a (last?) problem, but it's about motors, so I'm going to create a new topic for it.
Thanx again

manu