Must be DSP problem no matter what model it is. TX-SR/NR OR even RZ Series.
(1)If old model TX-SR/NR, you should replace the BGA DSP Q3001 "D830K013A/BZKB" TO "D830K013DZKB"IF DZKB get damaged, replace it with same DSP Chip-DZKB.
(2)For Tx-SR series, the DSP Q201 TMS320D788E001B SHOULD BE replaced with same model.
(3)For new model, RZ series the DSP Q3404 CS49844 should be replaced with same model.
(4)Crystal marked X201/3001/3404 should be replacd.