Dreamcast:Digital Audio (SPDIF) Mod

Example completed install.

Original guide adapted from a post by citrus3000psi.

This guide assumes the DAC in your Dreamcast is a PCM1725.

Required Materials

• Pep Audio 1.2 PCB
• If using TOSLINK:
  • TX178A (TOSLINK port)
  • TOSLINK PCB by citrus3000psi.
• If not using a TOSLINK port, you will need your own jack.

Installation

1. There exists an issue (as noted by FireBrandX) with the Pep Audio PCB where some of the boards have extra ground fill in front of the pins and cause shorts. Use a multimeter to make sure none of the pads (GND excluded) have continuity to GND. If you do find continuity, you will need to use a hobby knife to cut off the area marked in red below:
   • 
2. Assemble the Pep Audio PCB.
3. Bridge the "SAT" pad on the Pep Audio PCB to the pad next to it (although it's for Saturn, it's the same setting for Dreamcast).
4. On the top of the motherboard, solder wires from these legs on the DAC to the matching pads on the Pep Audio board.
   1. DATA on motherboard to DAT on Pep Audio PCB (not DATA!).
   2. BCK on motherboard to BC on Pep Audio PCB.
   3. LRCK on motherboard to LRC on Pep Audio PCB.
   4. MCLK on motherboard to MC on Pep Audio PCB.
   5. +5 on motherboard to 5V on Pep Audio PCB.
   6. GND on motherboard to GND on Pep Audio PCB.

   

5. Connect the output jack:
   • If using a TOSLINK port, connect +5V and GND to it. Also connect DATA (not DAT!) on the Pep Audio PCB to the In on the TOSLINK PCB.
   • If using your own SPDIF port, connect DATA on the Pep Audio PCB to the data pin and GND to GND.
6. Partially reassemble, snaking the board past the metal shield as shown below:

   

7. Mount the output jack on the case.