rocknroller
Active Member
Problem: All audio sources are muted in the power amp section - no output from speakers and no blown fuses.
Using Aux as the input source path, I get audio past the preamp at the test point jumpers 72/44 and 43/72. Audio through caps C511/C512, but not through Q503/504 (Listed as 2SK117-GR or Y, 2SK34-C or D - I guess these are audio gates?). See schematic below
Following back through D503/504 (which are good) to the left hand side of the circuit, this seems like the controller of those gates but Q502 collector has a bad voltage of -8v. Why?? This may not be the ultimate source of the amp issue, but seems to be why the audio isn't progressing any further in the circuit.
Using Aux as the input source path, I get audio past the preamp at the test point jumpers 72/44 and 43/72. Audio through caps C511/C512, but not through Q503/504 (Listed as 2SK117-GR or Y, 2SK34-C or D - I guess these are audio gates?). See schematic below
Following back through D503/504 (which are good) to the left hand side of the circuit, this seems like the controller of those gates but Q502 collector has a bad voltage of -8v. Why?? This may not be the ultimate source of the amp issue, but seems to be why the audio isn't progressing any further in the circuit.