Hum that doesn't go away when volume is turned down is caused by power supply or audio stages.
Is the 6F5G shielded? Pull this tube. Does hum go away?
Is cap C27 in place, chassis to AC line?
Did you notice negative side of all electrolytic caps do not connect to chassis?
The schematic shows a resistor and cap filter was added to bias voltage for your 6F6 tubes. This would reduce hum.
http://www.nostalgiaair.org/PagesByModel/064/M0017064.pdf
Norm
:I get a loud hum on my Silvertone 4486. I have changed the filters. Resoldered grounds. Checked tubes and replaced the phase changer 6C5. When I touch the chassis any place almost all of the hum goes away. Have grounded the chassis but doesn't help. Loud hum there at zero volume. Does get stations when volume is up but has loud hum in the sound.
:
:John
:
: Hum that doesn't go away when volume is turned down is caused by power supply or audio stages.
:
: Is the 6F5G shielded? Pull this tube. Does hum go away?
:
: Is cap C27 in place, chassis to AC line?
:
: Did you notice negative side of all electrolytic caps do not connect to chassis?
:
: The schematic shows a resistor and cap filter was added to bias voltage for your 6F6 tubes. This would reduce hum.
:
:http://www.nostalgiaair.org/PagesByModel/064/M0017064.pdf
:
:Norm
:
::I get a loud hum on my Silvertone 4486. I have changed the filters. Resoldered grounds. Checked tubes and replaced the phase changer 6C5. When I touch the chassis any place almost all of the hum goes away. Have grounded the chassis but doesn't help. Loud hum there at zero volume. Does get stations when volume is up but has loud hum in the sound.
::
:
I noticed the lack of shields and tried adding one to the 6Q7G and it got rid of all the hum. Now have fairly low volume with the volume control turned all the way up. Any ideas on low volume?
:
:
:
:
:
:
::John
::
:: Hum that doesn't go away when volume is turned down is caused by power supply or audio stages.
::
:: Is the 6F5G shielded? Pull this tube. Does hum go away?
::
:: Is cap C27 in place, chassis to AC line?
::
:: Did you notice negative side of all electrolytic caps do not connect to chassis?
::
:: The schematic shows a resistor and cap filter was added to bias voltage for your 6F6 tubes. This would reduce hum.
::
::http://www.nostalgiaair.org/PagesByModel/064/M0017064.pdf
::
::Norm
::
:::I get a loud hum on my Silvertone 4486. I have changed the filters. Resoldered grounds. Checked tubes and replaced the phase changer 6C5. When I touch the chassis any place almost all of the hum goes away. Have grounded the chassis but doesn't help. Loud hum there at zero volume. Does get stations when volume is up but has loud hum in the sound.
:::
::
:
Seems like you figured out the hum problem. 6Q7 and 6F5 are both used as 1st audio amp.
Here is what must be wrong. The wire connecting top of the 6Q7 should go to a cap and then center of the volume control. Something is open in this line. Maybe the wire broke? Has the cap been replaced?
Norm
Mine is the chassis that uses the 5Y3. Doesn't use a 6F5 tube, uses a 6Q7. Doesn't use a C27. Maybe I should add this cap.? None of the tubes are shielded. Should any be shielded?
:
:I noticed the lack of shields and tried adding one to the 6Q7G and it got rid of all the hum. Now have fairly low volume with the volume control turned all the way up. Any ideas on low volume?
::
::
::
::
::
::
:::John
:::
::: Hum that doesn't go away when volume is turned down is caused by power supply or audio stages.
:::
::: Is the 6F5G shielded? Pull this tube. Does hum go away?
:::
::: Is cap C27 in place, chassis to AC line?
:::
::: Did you notice negative side of all electrolytic caps do not connect to chassis?
:::
::: The schematic shows a resistor and cap filter was added to bias voltage for your 6F6 tubes. This would reduce hum.
:::
:::http://www.nostalgiaair.org/PagesByModel/064/M0017064.pdf
:::
:::Norm
:::
::::I get a loud hum on my Silvertone 4486. I have changed the filters. Resoldered grounds. Checked tubes and replaced the phase changer 6C5. When I touch the chassis any place almost all of the hum goes away. Have grounded the chassis but doesn't help. Loud hum there at zero volume. Does get stations when volume is up but has loud hum in the sound.
::::
:::
::
: