Line6 DL4 pedal in for repair relating to a noisy output. The left output exhibits noise superimposed on the output signal when the effect is engaged but the right output is normal. Both outputs are clear with the effects bypassed but this pedal boasts true bypass by means of a pair of mechanical relays.
The reported fault was confirmed before removing the PCB from the casing but the with the board in a bench pcb holder another issue occurred. A much reported refusal to power on when the jack plug was inserted into the left mono input. This jack socket utilises the ground contact via r47 to the max887 power supply chip u14 shut down pin. Removing the socket proved fruitless so tracing back to r47 found this little surface mount resistor requiring solder reflow. Now the power supply again switches on when the jack is inserted. There are many instances on the Internet of advising that the ROM chip reseat is required to resolve power issues but this pedal proved otherwise.
ROM was removed, cleaned and reseated to rule out root cause for the noise issue but not the case, I believe the issue resides around U4 the CS4223 ADC/DAC.
Now to find it.
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