DB4 / DB8 / System 6000: Sync errors on digital inputs

Question

Our DB8 unit reports sync errors on some of its digital inputs from time to time. Do I need to clear these errors? How can I resolve it?

Answer

The DB4 / DB8 / System 6000 includes a unique feature to constantly monitor its digital inputs. If any input looses or gains one sample compared to what is selected as Clock Master, an error indication for this input lights up. The error automatically disappears once the input is back in sync again.

There is no need to reset the machine, but you should investigate why the sample slips appear, and how often they happen. The error light is an indication that something is wrong in the installation or setup, and can be used to diagnose the problem.

Note that all inputs have to be synchronized to the same source. It's not enough that they are all 48 kHz, they also have to be referenced to the same master clock. If you're in a TV station, the clock should be derived from the picture frame rate somewhere in the installation.

Try to listen to a sine tone e.g. at -20 dBFS passed through the input that indicates sample slip. If you hear occasional glitches, one of the upstream devices is not locked to the same master clock as unit. If you hear harmonic distortion on the sine tone, the upstream device is probably running at the wrong sample rate.


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