YA I had a simular problem with a bakelite block in a philco model 60. It said the 2 capictors went to ground. after I hooked it up like that the radio didnt work. turns out the one cap goes to ground and the other jumps between the other two lugs. Good thing for scmatics.
I was looking at a drawing of a 1930s radio and I was tracing a wire in the power supply. In the drawing it went from the positive side and it weaved its way around to the negative side. That's right a direct short. Of course that's not the way it was really wired. Glad you pointed out to everyone that you are going to find errors with the documentation sometimes.
I guess the replacement bakelite block Philco made was not as universal as they thought!
Another thing to watch out for is the negative floating B - . The 10 MFD cap floats the B- voltage for some sort of bias. The circuit has to be carefully ohmed out to make sure the 8 MFD caps which are part of the Pi filter network do not go to ground!
This type of potted tone control setup is found on many of the old Philcos. It's nothing more than another bakeite-style cap holder.
Recommendation: Don't bother re-potting. It's not needed. Just insulate the cap leads, place them inside and solder them in place...just like you did with the bakelite blocks.
I ended up potting it with GE Silicone II. Mainly because the interior of the cap is visible. Now, when the silicone cures, I can install it and keep going. I'm starting to see light at the end of the tunnel and hopefully it's not a locomotive.
YA I had a simular problem with a bakelite block in a philco model 60. It said the 2 capictors went to ground. after I hooked it up like that the radio didnt work. turns out the one cap goes to ground and the other jumps between the other two lugs. Good thing for scmatics.
daheick 2 years ago
Good tips. Nice job.
Wayne
simplertimes1 2 years ago
I was looking at a drawing of a 1930s radio and I was tracing a wire in the power supply. In the drawing it went from the positive side and it weaved its way around to the negative side. That's right a direct short. Of course that's not the way it was really wired. Glad you pointed out to everyone that you are going to find errors with the documentation sometimes.
AllAmericanFiveRadio 2 years ago
I guess the replacement bakelite block Philco made was not as universal as they thought!
Another thing to watch out for is the negative floating B - . The 10 MFD cap floats the B- voltage for some sort of bias. The circuit has to be carefully ohmed out to make sure the 8 MFD caps which are part of the Pi filter network do not go to ground!
Lockemeister 2 years ago
This type of potted tone control setup is found on many of the old Philcos. It's nothing more than another bakeite-style cap holder.
Recommendation: Don't bother re-potting. It's not needed. Just insulate the cap leads, place them inside and solder them in place...just like you did with the bakelite blocks.
You're doing great. Stay the course.
Regards,
John
joernone 2 years ago
I ended up potting it with GE Silicone II. Mainly because the interior of the cap is visible. Now, when the silicone cures, I can install it and keep going. I'm starting to see light at the end of the tunnel and hopefully it's not a locomotive.
Lockemeister 2 years ago