08-28-2022, 05:54 PM
Hi Murf.
If the Radio has an Aux / Phono, (Schematic shows a "Television" Connection) Inject an audio signal there. You can make up a cable to inject a computer or CD Player headphone level signal into this point. Switch to that to determine if direct Audio sounds good. "Calibrate" by switching while radio level is good. If Aux Audio level did not change when the radio level did change, that exonerates the "Audio" section. troubleshoot the "radio" section. If the Aux level also dropped, then troubleshoot the audio and power supply sections. Possible issue areas in the audio and PS sections may be the B+ / C- Resistors R17 through R20, the voltage and signal divider resistors for the phase Inverter (R14, 15, 13 and 2 numbers that I can't read of the NA Schematic). Of course, transformer windings, the speaker rectifier and audio tubes are suspect. In the radio section all is suspect including cathode resistors, IF transformer secondaries, etc.
Good luch
If the Radio has an Aux / Phono, (Schematic shows a "Television" Connection) Inject an audio signal there. You can make up a cable to inject a computer or CD Player headphone level signal into this point. Switch to that to determine if direct Audio sounds good. "Calibrate" by switching while radio level is good. If Aux Audio level did not change when the radio level did change, that exonerates the "Audio" section. troubleshoot the "radio" section. If the Aux level also dropped, then troubleshoot the audio and power supply sections. Possible issue areas in the audio and PS sections may be the B+ / C- Resistors R17 through R20, the voltage and signal divider resistors for the phase Inverter (R14, 15, 13 and 2 numbers that I can't read of the NA Schematic). Of course, transformer windings, the speaker rectifier and audio tubes are suspect. In the radio section all is suspect including cathode resistors, IF transformer secondaries, etc.
Good luch
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
