I replaced the filter with a 160uF rated at 200V. (The original capacitor was 135uF at 150V.) The hum is gone. However, I have to turn the volume all the way up to hear any stations; even then, the FM stations are barely audible with an external antenna (no AM reception at all). The filter capacitor voltage now reads over 100Vdc. The collector voltage on the output power transistor reads in the 90's. Does this mean that I have an open circuit somewhere?
I double checked the solder connections to ensure continuity, and they were fine. Does anyone have a schematic they can send, along with suggestions? Thanks in advance for your help.
Coupling caps in a transistor are usually electrolytic. They dry out and lose value just like filters. It's best to replace all electrolytic caps.
Norm
:When I first acquired this solid-state radio, a loud hum was heard at first turn on, then it would die down, and I could hear the stations. (The hum did not go away completely, so I decided the filter cap. had to go.) Early last week, I tried the radio again and heared the loud hum continuously.
:
:I replaced the filter with a 160uF rated at 200V. (The original capacitor was 135uF at 150V.) The hum is gone. However, I have to turn the volume all the way up to hear any stations; even then, the FM stations are barely audible with an external antenna (no AM reception at all). The filter capacitor voltage now reads over 100Vdc. The collector voltage on the output power transistor reads in the 90's. Does this mean that I have an open circuit somewhere?
:
:I double checked the solder connections to ensure continuity, and they were fine. Does anyone have a schematic they can send, along with suggestions? Thanks in advance for your help.