When i turn on my ps3 its just a blank screen nothing shows up

Hello. There are a few causes for this. I will list acouple solutions for you.

1. Reset the Video Output Settings. While the PLAYSTATION 3 system is in standby mode (red light on the front of the system), hold down the touch-sensitive On/Off button on the front of the system until the system goes into standby mode again . (So the light cycle would go from: red light to --> green light --> then back to red light) This will ensure that you have held down the On/Off button long enough to reset the Video Output Settings. Once you turn it back on, it should work fine.
2. If option 1 does not work call Sony because the video out chip has blown or come unsoldered.

I hope this helps. Good luck to you.