07-29-2012, 08:58 AM
Arrrgh. (That's frustration, not piratey talk).
I had installed a fuse on the incoming hot line, plugged it in and powered up the radio after seating all the tubes. Only the two 41 audio amp tubes lit, then the fuse blew after a couple minutes.
So off I go, scanning the schematic for possible causes for my trouble. First thing I realize is that the 5Y4G rectifier tube has an open filament- probably one of the original tubes, and no big deal to replace. I also went through and took some resistance readings on other components. I found the bad primary winding on the audio output transformer-- while not my main suspect, it needs to be dealt with.
However, a few days later, it suddenly hit me right between the eyes. I can't believe I didn't consider this before, but I never replaced the filter caps at the power transformer (facepalm).
I had installed a fuse on the incoming hot line, plugged it in and powered up the radio after seating all the tubes. Only the two 41 audio amp tubes lit, then the fuse blew after a couple minutes.
So off I go, scanning the schematic for possible causes for my trouble. First thing I realize is that the 5Y4G rectifier tube has an open filament- probably one of the original tubes, and no big deal to replace. I also went through and took some resistance readings on other components. I found the bad primary winding on the audio output transformer-- while not my main suspect, it needs to be dealt with.
However, a few days later, it suddenly hit me right between the eyes. I can't believe I didn't consider this before, but I never replaced the filter caps at the power transformer (facepalm).
