This Pioneer VSX-D908S analog/digital receiver will not pass any audio as long as the dsp board is plugged into the unit.
First I'll explain what works with this set. With the dsp board removed, all analog input functions work as long as you select the direct mode. The direct mode bypasses the digital board completely. For example, if you've selected CD direct (analog) for the source, there is an electronic mode switch, located on the main control board, which selects between dsp, direct, or 5.1. This switch will select the direct mode correctly and pass the audio signal. What doesn't work is if you plug in the dsp board, the audio does not pass through the same analog/digital mode selector on the main control board even in direct (analog) mode. The dsp board is quite complex but there is a uP there that communicates with the control board's uP. Now here's where I have, hopefully, an easy question. Two of the pins on the uP of the dsp board are labeled Xin and Xout and they have no signal. On the uP of the control board, there is good signal at the uP on the Xin and Xout terminals. Can I generalize that any uP that has two terminals labeled Xin and Xout should have a continuous running clock signal on these two terminals? Also, would the uP itself be the most likely failure to cause this symptom? By the way, I spent a fair amount of time removing all the boards and soldering numerous bad connections.
Thanks for your reply.