10-26-2018, 02:14 PM
My 6A7 and a few other tubes arrived today from Bob D's FindATube so I was all set to fire the 66B up and get it aligned...ho ho ho
Getting past the dim bulb test OK I powered it up at about 115v. The 80 filament lit as did the dial lamp but the set was ominously quiet! I flipped the tone switch and did hear a small click through the speaker and a screwdriver on the cap of 75 produced a buzzing through the speaker so at least the audio seems to work. Voltages on the tubes were as follows:
[Image: https://www.dropbox.com/s/qeoad4s7k6uzv4....jpg?raw=1]
Voltages on the electrolytics were:
Electrolytic Cap#50 (red lug)= 293v
Electrolytic Cap#50 (plain lug)= 350v
Electrolytic Cap#49 = 0v
Gotta be the choke #48... and indeed when I checked it (I swear I checked it earlier
) it is open. Its a bit of a tight fit where its located so I'll have to see what I can find to replace it. I don't have a spec on it but following Terry's previous advice on an open filter choke is go with the highest Henrys that fit the physical dimensions for the choke. More later...
Getting past the dim bulb test OK I powered it up at about 115v. The 80 filament lit as did the dial lamp but the set was ominously quiet! I flipped the tone switch and did hear a small click through the speaker and a screwdriver on the cap of 75 produced a buzzing through the speaker so at least the audio seems to work. Voltages on the tubes were as follows:
[Image: https://www.dropbox.com/s/qeoad4s7k6uzv4....jpg?raw=1]
Voltages on the electrolytics were:
Electrolytic Cap#50 (red lug)= 293v
Electrolytic Cap#50 (plain lug)= 350v
Electrolytic Cap#49 = 0v
Gotta be the choke #48... and indeed when I checked it (I swear I checked it earlier
) it is open. Its a bit of a tight fit where its located so I'll have to see what I can find to replace it. I don't have a spec on it but following Terry's previous advice on an open filter choke is go with the highest Henrys that fit the physical dimensions for the choke. More later...
