When I opened it up I found that there was no back cover to the digital in connectors. With no back cover, there is no place for the photo transistor to be placed, and to my surprise, even though they are labeled optical 1 and 2 on the board they are definitely not. In fact, the "proprietary" connector is some aborted 3.5mm stereo plug with locking shield deal. So, that is odd, but not necessarily unusual, it could be S/PDIF output/input, which can be carried over normal old 75 ohm cable, but the problem is, the $100 digital cable for this thing looks like a fiber optics cable, with weird ass ends on it. Add to that, that the cable is supposed to be directional (according to the manual) and neither fiber or S/PDIF should be, I decided to investigate a little further.
I took apart the ends on the digital cable, and lo and behold, it is fiber optic in there. It has a fiber optic transmitter in one end and receiver in the other (making it directional) and it picks up VCC, GND, and Signal via the 3.5mm phone plug. It's really pretty clever, AFAIK no one else has ever made a cable like these, so they can charge what they want for them, and they can insure that it is only used with their devices. Screw that!
I replaced the proprietary "abortion jack" on digital input 1 with a standard toslink receiver module. Unfortunately, the receiver module is not pin for pin compatible, so I had to hack up the board a bit, but IMO, it is worth it. You will see in the pictures bellow, that I had to cut some traces and seperate the old "ground" through hole from the rest of the ground plane. The only difference between the toslink receiver and the "abortion jack" is VCC and GND are flipped. So, the old ground through hole had to become the VCC, and the old VCC had to be GND. I cut the power traces on top of the board, soldered in two jumpers. VCC goes straight to the power pin on the receiver on top of the board, ground goes to an old shield mount point off to the side to keep the jumpers a safe difference apart. On the bottom of the board I had to cut the GND through hole from the ground plane, then I jumpered from the new ground point, to a bare patch on the ground plane that I cleaned up, then to a final mounting point from the old jack that is also tied to the ground plane.
Anyhow, it works perfect, and that is the important thing. I needed to mod this thing to be used as my sound processor for my up coming car pc install. In hind sight, I should have just made a little adapter dongle since 3.5mm phone plugs are a dime a dozen and I can cut PCB's on the mill. I'm actually looking for another one of these processors with it's external controller, or the DVH940 for the next car pc I have planned. For now, this one should work out well in the jetta.
I know I have come across other threads online of others wanting to use these processors with other input devices. I have not found anyone who got it working, so I thought I would document what needs to be done in case it can help someone else.
Pics:
Later,
Jason
