Posts: 70
Threads: 17
Joined: Jan 2006
City: Newbern
State, Province, Country: Tennessee
While waiting for parts for my 87 I finished up my 77. All excited I fired it up. No volume until I touched the volume control shaft, top of the 1st rf tube (24), or the coil #5. Checked coil resistance 6.2 ohms from cap of 24 to gnd. matches other coils, volume control pod, ground connections, and voltages, all look ok. Ran a jumper from 24 cap connection on coil to ant. got a little better, but not as good as if you touch it. Some stations you can hear faintly, but others not until you touch. Tried swapping tubes, no difference. Probably something simple staring me in the face. Frustration got the best of me at this point. Any and all ideas welcomed. Thanks ahead of time, Richard
Posts: 1,703
Threads: 55
Joined: Sep 2005
City: Evanston, IL
Check for continuity in both windings of transformer #2;
Both sections of coil #5;
All three sections of coil #9 and #10.
Check for B+ on plates of both RF tubes. If missing on either plate, it's a coil winding associated with that tube.
(I assume you already replaces all the wax-paper caps and any out of tolerance resistors.)
Posts: 70
Threads: 17
Joined: Jan 2006
City: Newbern
State, Province, Country: Tennessee
Hi Chuck, Thanks for the reply. #2 from volume center tap to gnd. 20.9 ohms, gnd. to tab for coil #5- 6.2ohms. Coil #5 center tap 6.2 and 6.1 ohms. Coil #9- 45.7, 6.3, 1.5 ohms. Coil #10- 48.5, 6.2, 1.5 ohms. B+ voltage on plates 154. All capacitors and out of tolerance resistors were replaced. Also before replacing anything there was a wire bridge on the bc resistor connecting H & J. I removed it since I could not find it on any schematics or updates. The resistor tests good between H & J 2,054ohms. specs. 2,000 ohms. Also a 24k dog bone resistor was in parallel with resistor #12 a 100k. I also remove it. Both seem to have been added a while back. Thanks, Richard
