Display has just black screen

[Fleder]

i order the pololu one from ebay. will receive it next week and hope it will work

Good choice.
Especially with your power supply, you do not want to rely on cheap noname stuff with unknown life expectancy
At least that is my point of view.

I am using cheap china stuff, too, but i don't expect them to be perfect.

[Popcorn]

Looks like you soldered the wrong video cable. Video goes to the Square pin. GND goes to the circle one. Flip the wires and resolder those connections

[Ka-dir]

As i send you a tutorial via PM yesterday, i would like to throw light on this problem in public for the other users with the same display.
You can make this display work in only 3 steps:
1) desolder IN4002 and short circuit the soldering points
2) desolder 22UH/5*5 inductance and short circuit the soldering points
3) desolder IC AP6502 and short circuit Pin 2 and Pin 3

You find some visual instructions attached. Have fun!

[MegaMike]

I'm sorry, how do you short circuit these?