Thank you for your replies:
I think that you have to change the voltage from 3.3 V to 5 Volt. If you look at the break-out board of ADAFRUIT http://www.adafruit.com/products/269
than you can you see that they converted the voltage!
Instead of using a level shifter chip, I used voltage dividers on CS and SCK pins to put into max31855KASA+ 3.3V and not 5V....But MISO is directly connected to the arduino MEGA Digital pin 50 without any level shifting, because as I read, Arduino recognises 3,3V as a logic 1. Do you think I will make this output 5V instead 3v3?
I would make sure that you have a good solder joint in the SOIC to DIP. use a straight pin contact to the top of the pins of the SOIC and the regular lead to the DIP. so that you are seeing if the continuity is there. I found an open this way that was pretty elusive.
Always I solder any chip I see If the solder joints are made well with my multimeter, for not having problems like this...Thank you for your suggestion, this problem seems similar to this, but it isn´t the case