Defeat SCMS page


For this modification you have to things to your DAT recorder that surely void your warranty, and can possibly ruin it. Use at your own risk!

By the way, this circuit could be illegal in your country. Please consider it "for educational purposes only" :-).

I modified a Sony DTC790 DAT recorder using a circuit designed for recorders with a CXD2601 chip. This schematic can be found at DAT heads home page, and with more info on Philipp Born's page. The Sony DTC790 has a CXD2605 chip, but it is compatible enough for the SCMS killing circuit. It is my guess the circuit will work with all recorders with the internal signals EXCK, SDS0, SBSY. The circuit disables SCMS on all incoming digital data streams. Analog input recordings and play back data streams are not affected.
All the used signals have testpoints near the CXD2605 chip, so no soldering on the chip's pins is neccesary.

Recorders known to have a CXD2605:

(tested with this, see details below)
You will need SMD parts for this, or sacrifice your battery compartment.
This machine seems to be hardware identical to the TCD-D7.

Implementation details DTC790

I connected the wires to the board to the test points near the CXD2605 on the lower side of the board. Note that the test point for pin SDS0 is labeled SDS1, so you have two of them. The true SDS0 testpoint is connected to pin 25 of the CXD2605.

The wires can be led through a small free hole in the board to the upper side, where plenty of room is available for attachment.

Three signal connections (EXCK, pin 23; SDS0, pin 25; SBSY, pin 26), and two for the power supply. You can disable the circuit by disconnecting the line to SDS0. See the connection diagrams I made for the prototypes: picture 1 and picture 2.

Below is a picture of a board I designed for this circuit, including a coaxial output interface (click on it to get the PostScript file).

Other ways to defeat SCMS

Stand alone SCMS killers: Not really SCMS but related:

If you have a stand alone audio CD recorder see this article from Stereophile