Hi guys im new here ive got 2 nes systems. My problem is one works the other doesnt. Ive put a new 72 pin in both of them and cut the lock out chips but the one that still doesnt work gives me a black screen no sound or anything else just black screen. Is there anything else to check other than the 72 pin inside the nes on the board itself. Thanks.

Nothing no one knows?? Thoughts

If the screen is just black and not the blinking screen, have you tried RF adapter?  

Start from scratch.  When you push the power button in, does it lock down?  Does pushing the power button in produce a different type of black screen than when there is no power?  Does the screen appear to "blink" about once every second, or not at all?  Is the power light lit?

Sounds to me like you may have a bad power adapter.  Grab yourself a cheap multimeter at your local hardware store and see if your adapter is putting out the voltage that it is supposed to (listed on the back of the adapter).

A misfed cartridge (bad connection or lockout chip activated) will produce a black screen that appears to "blink" about once every second in concert with the red power light as the system attempts to reset itself.

If you don't see even this evidence, then you're probably either breaking down at the power supply or the RF adapter as mentioned above.

Post results.

Hope that helps.