This ribbon cable connects the top and the bottom of the CDJ. If you experience latency, frozen screen, communication errors or other equal issues, this is step one in the repair process. It is super easy to replace this part.
The DDD1640 is a 29 pin ribbon cable acting like a highway of communication on the CDJ2000 and the CDJ2000Nexus from Pioneer DJ. If you ever experience any sort of ERROR codes on one of these players, first stop is to inspect this part. If one of the small chrome connecters are bend or broken, the communication between the top and the bottom of the CDJ wan't work – causing an ERROR. To check if this part is to blame for a problem, simply replace it with a brand new one. If you service or repair CDJ2000 or CDJ2000Nexus from time to time, I would keep a pair of these DDD1640 ribbon cables close.