04-03-2016, 07:46 PM
Well I have success, I hope. I ended up taking the transformer apart again, this time I figured I might as well unwind it some. I discovered a few things that may or may not have made a difference.
1. The 45's filament winding was the outer most, and someone long ago had replaced it. The core was wrapped in black vinyl electrical tape and the winding looked like the ground wire form common household 3-wire electrical wiring. It looked fine otherwise.
2. The 24&27's filament winding is double wound and soldered together at both ends. It was all coated in varnish so it looked original. The burn spot in the tape is located where one of the leads and the CT lead come out the side. The CT was repaired long ago. Whom ever did the repair did not solder it back in the original spot, they were off by about an inch. Part of the original CT wire was still under all the tape. It was also wound off from center so part of the winding was right near the edge of the transformer core.
So I unwound the second filament winding as well, resoldered the CT in the correct spot. I then rewound the 24&27 filament winding, making sure it was spread evenly and centered more over the core. I then wound back on the 45's filament back on, also making sure it was evenly spaced and centered.
I had to do this twice because I used a little too much tape between winding's and the core would not fit back into the bobbin. I also broke a couple of the high-voltage leads and had to fix them. Once I got it back together I tested it and it seemed ok, no shorts. I then hooked it up the the radio, only connecting the 24&27's filament section. I placed all the 24& 27 tubes in and brought it up slowly. Low and behold it works! All filaments are lite with 2.5vac and pulling 8 amps after they warmed up.
It has been "cooking" for about an hour and the transformer is barely warm. There is a small buzz now, but the transformer is not mounted yet. I hope this fixes it, but I will keep an eye out for another transformer or have one made just in case.
Thanks for all the suggestions and help. I doubt I would have taken it back apart and unwound it with out your questions.
Other then the CT not soldered back at the original spot, and the winding's not centered on the Bobbin, I am not sure what fixed it or exactly the reason it just was weak under a load. I did also retouch the solder on both ends of the second 2.5vac winding. Maybe that helped as well.
1. The 45's filament winding was the outer most, and someone long ago had replaced it. The core was wrapped in black vinyl electrical tape and the winding looked like the ground wire form common household 3-wire electrical wiring. It looked fine otherwise.
2. The 24&27's filament winding is double wound and soldered together at both ends. It was all coated in varnish so it looked original. The burn spot in the tape is located where one of the leads and the CT lead come out the side. The CT was repaired long ago. Whom ever did the repair did not solder it back in the original spot, they were off by about an inch. Part of the original CT wire was still under all the tape. It was also wound off from center so part of the winding was right near the edge of the transformer core.
So I unwound the second filament winding as well, resoldered the CT in the correct spot. I then rewound the 24&27 filament winding, making sure it was spread evenly and centered more over the core. I then wound back on the 45's filament back on, also making sure it was evenly spaced and centered.
I had to do this twice because I used a little too much tape between winding's and the core would not fit back into the bobbin. I also broke a couple of the high-voltage leads and had to fix them. Once I got it back together I tested it and it seemed ok, no shorts. I then hooked it up the the radio, only connecting the 24&27's filament section. I placed all the 24& 27 tubes in and brought it up slowly. Low and behold it works! All filaments are lite with 2.5vac and pulling 8 amps after they warmed up.
It has been "cooking" for about an hour and the transformer is barely warm. There is a small buzz now, but the transformer is not mounted yet. I hope this fixes it, but I will keep an eye out for another transformer or have one made just in case.
Thanks for all the suggestions and help. I doubt I would have taken it back apart and unwound it with out your questions.
Other then the CT not soldered back at the original spot, and the winding's not centered on the Bobbin, I am not sure what fixed it or exactly the reason it just was weak under a load. I did also retouch the solder on both ends of the second 2.5vac winding. Maybe that helped as well.
