Zenith 10S690 Volume Control Issues

[old_coot88]

Check that there is plate voltage on the 6A8 and 6K7 (pin 3 of both tubes).

Also check screen grid voltage on both tubes (pin 4 of both).

[vortalexfan]

Originally Posted by old_coot88

Check that there is plate voltage on the 6A8 and 6K7 (pin 3 of both tubes).

Also check screen grid voltage on both tubes (pin 4 of both).

Geez this radio is turning out to be a pain in the butt, because I have to put the radio in the cabinet to test it (the antenna is in the cabinet and the radio won't work without that antenna attached to it) and the speaker is too big for me to take out of the cabinet and plop it on my bench next to the radio, so I have to keep removing and installing the radio from the cabinet to do all of these tests.

So what are you thinking may have happened if you don't mind me asking?

Also I rechecked the radio and it is indeed dead silent except for the popping noise it makes when changing the band switch, there is absolutely nothing on the radio reception wise when tuning through the dial not even a little bit of static or hiss.

I also checked all of the tubes and they all tested fine (they are all the original Zenith branded Tubes to this radio except for the 6A8 tube and the 5Y4 Rectifier tube which are RCA and GE Branded tubes respectively.)

[old_coot88]

Do you have a spare 6A8 to try for a sub? If not, try wiggling the 7G7, 6A8 and 6K7 in their sockets (with power on, volume high). Also try tapping them to check for intermittents.

This is a dumb question, but is there any chance the 6A8 and 6K7 coulda got interchanged?

[vortalexfan]

Originally Posted by old_coot88

Do you have a spare 6A8 to try for a sub? If not, try wiggling the 7G7, 6A8 and 6K7 in their sockets (with power on, volume high). Also try tapping them to check for intermittents.

This is a dumb question, but is there any chance the 6A8 and 6K7 coulda got interchanged?

I never touched any of the tubes when I was recapping this radio or when I undid the B- wiring from the negative leg of the volume control.

The only time I touched the tubes was to test them in my tube tester to make sure there weren't any dead ones, but I disconnected them one at a time so that there wasn't a chance for them to be put into the wrong socket.

I don't have any spare 6A8 tubes unfortunatly, and the weird thing is that the original owner of this radio replaced the original 6A8G tube with a metal 6A8 tube so because of that they ended up throwing out the original tube shield that went in that spot and unfortunately the metal 6A8 tube doesn't fit into the tube socket very tightly like the original 6A8G did so I have a feeling that the replacement 6A8 tube may not be making very good contact with the tube socket because the tube pins don't seat all the way into the tube socket.

I also checked the 7G7 tube and the pins looked kind of crusty looking but I wasn't sure if that would of caused the issue I was having or not (I know Loctal tubes are notorius for making bad contact between the tube pins and the socket).