philco 41-280 volume control - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: philco 41-280 volume control (/showthread.php?tid=22279)

---

philco 41-280 volume control - Radioengineer - 03-10-2021

Hi,
I just rebuilt a 41-280. Replaced ALL wiring ,even in the IF cans,resistors and caps.The BC band is working great and all tube voltages are right on.I was getting ready to do a IF and RF alignment
My question is, at min. volume, the audio can still be heard. I have even grounded the wiper on the pot and the audio is still there.It is not loud but, can be heard.It is leaking past the pot somewhere.
It doesn`t take much of a turn to get the volume pretty loud.

---

RE: philco 41-280 volume control - Radioroslyn - 03-10-2021

The that thing comes to mind is it could be internal leakage in the det/1st audio tube. Have hear it a lot with sets that use 'at6 and 'av6 tubes.

---

RE: philco 41-280 volume control - Radioengineer - 03-10-2021

That makes sense. I even tried another 7C6 with the same problem.I`m sure the customer will want zero audio with the pot turned all the way down. Should I try putting in a resistor in series with the green secondary IF to the diode?

---

RE: philco 41-280 volume control - Radioengineer - 03-10-2021

If I ground the grid on the 7C6 no audio.They are using -.6v bias there.

---

RE: philco 41-280 volume control - Radioroslyn - 03-10-2021

Try grounding the DIODE plates on the 7C6. It's not really the det tube it's hooked to the avc line.

---

RE: philco 41-280 volume control - Radioengineer - 03-15-2021

Hi,
If I ground out the diode plate (pin 6)with the green secondary wire from the IF can it is dead quiet.No audio is heard at any volume.
If I ground out pin5 the audio is reduced but still there. If I ground the blue secondary wire from the IF can the audio is low but still there.
I even wired  in the volume control circuit from a 42-360 and still cannot mute the audio when the pot is turned down.

---