Hi!

The other day my combined preamp/dsp/dac stopped working - no sound at all.

In the box I have 2x toslink modules, and I use a relay to switch which input that is active. The module then connects to a miniSHARC from miniDSP, which then outputs 8ch I2S to a Buffalo 3.

I switched to the other to toslink module, but there was still no sound. My first guess was then that something went wrong with the miniSHARC, because it didn't registered any input signal from either of the modules. I then wired the toslink module directly to BIII, but couldn't still get any sound.

Then I decided to check the output signal from the toslink modules, and used a simple USB-scope. First time for me using a scope, and I wasn't sure how the SPDIF signal should look like. But I think what is showed in the picture is NOT how it should look:



(in order to verify that the scope was working, I checked the LRCK pin on the miniSHARC which showed a nice square wave at 48 kHz with 3.3V amplitude).

So, my guess is that the toslink modules have died? I use a LCDPS for power, set at about 5.5 VDC. I checked the pins of the regulators of the toslink - 5.5VDC on the left one and 3.3VDC on the right one (seen from the back of the board). The boards were assembled for TTL level output.

I need some help to understand what may have happened to the modules, so I can take precautions that it won't happen again. I guess I need to order another set…. Is there anything else I could check?

Best regards,

Mattias