I'm trying to fix a DL4 for a friend of mine.  When powered up, the unit is completely non functional and does not respont to any of the foot switches.  I tried the factory reboot procedure multiple times (i.e. hold the outer two switches and apply power) with no luck.

I removed the PCB from the housing and applied power to the unit with a plug inserted into the mono input.  All voltages on the board appear as expected (i.e. I am seeing appropriate values 1.8V, 3.3V and 5V power domains).  I probed the MCLK, LRCLK, SCLK, ADC and DAC nodes (labeled on the board) with an OScope and the MCLK is running at the expected 11.98MHz.  LRCLK, SCLK, ADC and DAC are not toggling at all (LRCLK, SCLK, ADC and DAC seem like they should be active all the time if they are operating as an I2S serial audio interface).

It appears that the Phillips microcontroller is not booting, hence no switching functionality or booting of the Motorolla processor.  Unfortunately I have no way to tell if the issue is the EEPROM or the Phillips microcontroller.  I guess the Motorolla processor could be a problem as well, but is appears that the microcontroller must function for any of the basic capability of the board to work.

Has anyone ever hear of this issue?  I've seen a post of a customer who had to replace the microntroller and was able to fix the unit (that appeared to be a supply short inside the part, which doesn't appear to be the case here).  This never left my friends house and was kindly used, so this feels like a reliability failure of one of the components.  I checked all four switches based on feedback to be sure and they're all good.

Are replacement EEPROMs and Microcontrollers available?  Any other ideas?

The unit has "DL4 v1.2" for the EEPROM and Rev:4A PCB.

Thanks,

Dave