RCA 10K Distortion Problem Help!!!

4/7/2001 3:33:41 PMNick Tillich

Hi,

Ok....I've been working on an RCA 10K console radio for awhile and I have been unable to get rid of a static/distortion problem. All the tubes check good and are clean, likewise is everything else on the chassis. The radio works excellently and I have had no other problems, but I have been unable to remove the distortion in the speaker. It does get louder with the volume and seems to be of a static-y nature. I definitely know that the problem is not in the speaker, so I don't know where to look next.....if anyone could point me in the right direction, I would really appreciate it.

Thanks, Nick

4/7/2001 10:49:39 PMNorm Leal

Hi Nick

Distortion is often caused by lack of negative grid bias on the audio output tube. Grid #1 must be negative in relation to the cathode.

In the RCA 10K it's a 6L6 tube. Pin #5 must be around 15 volts negative when measure from pin #8. A leaky capacitor connected to pin #5 can cause the problem if bias voltage is missing.

Norm

: Hi,

: Ok....I've been working on an RCA 10K console radio for awhile and I have been unable to get rid of a static/distortion problem. All the tubes check good and are clean, likewise is everything else on the chassis. The radio works excellently and I have had no other problems, but I have been unable to remove the distortion in the speaker. It does get louder with the volume and seems to be of a static-y nature. I definitely know that the problem is not in the speaker, so I don't know where to look next.....if anyone could point me in the right direction, I would really appreciate it.

: Thanks, Nick

4/7/2001 10:59:32 PMDenis Niehues

I think Norm hit the nail.. That cap feeding the grid
has to be leakage free, otherwise you get B+ fed to the input grid.
: Hi Nick

: Distortion is often caused by lack of negative grid bias on the audio output tube. Grid #1 must be negative in relation to the cathode.

: In the RCA 10K it's a 6L6 tube. Pin #5 must be around 15 volts negative when measure from pin #8. A leaky capacitor connected to pin #5 can cause the problem if bias voltage is missing.

: Norm

:
: : Hi,

: : Ok....I've been working on an RCA 10K console radio for awhile and I have been unable to get rid of a static/distortion problem. All the tubes check good and are clean, likewise is everything else on the chassis. The radio works excellently and I have had no other problems, but I have been unable to remove the distortion in the speaker. It does get louder with the volume and seems to be of a static-y nature. I definitely know that the problem is not in the speaker, so I don't know where to look next.....if anyone could point me in the right direction, I would really appreciate it.

: : Thanks, Nick