09-15-2024, 06:31 PM
Howdy,
Just another update on my progress (or lack thereof) and it's not good news. Underneath the chassis there are a number of splatter marks of a tar like substance, near the rectifier socket. Because of the burn marks on the rectifier socket, I looked more carefully at the transformer. I was able to easily remove the top cover. I discovered that this transformer had seriously. and I mean seriously, overheated. Whatever insulation that was used had melted and puddled in the cover. I cut all the wires and removed the transformer. I removed the bottom cover and it was nearly filled with melted 'stuff'. All the windings measure pretty close to what is on the schematic except for the HV secondary. It's supposed to be 160 ohms and measures 112. The, off center, center tap is supposed to measure 75 ohms to one HV leg and 85 ohms to the other. It measures 64 and 48 respectively. Even though there is continuity, I suspect some of the HV windings are shorted deep inside. I did check, and all the windings are isolated from one another. Not sure that would be the case with operating voltage applied. I'm not even sure I want to test the transformer with a variac. I don't trust that it has severely overheated and won't fail under load. So, I will have to start looking around for a 'parts' chassis either a 39-54 or 39-116. There may be other chassis that use the same transformer, but I'm not aware of any. I will not bother to do anymore work on this chassis as everything hinges on finding and installing a working power transformer. Oh, forgot to mention the safety capacitor is a total short and it's part of a bakelite block. I would try to take a look at the HV secondary, but it's buried underneath the LV filament windings. And before anyone asks, I'm not particularly interested in trying to re-wind the transformer. That's definitely not in my wheelhouse.
If anyone has any suggestions, I'd sure appreciate it!
Thanks all!
Rich
Just another update on my progress (or lack thereof) and it's not good news. Underneath the chassis there are a number of splatter marks of a tar like substance, near the rectifier socket. Because of the burn marks on the rectifier socket, I looked more carefully at the transformer. I was able to easily remove the top cover. I discovered that this transformer had seriously. and I mean seriously, overheated. Whatever insulation that was used had melted and puddled in the cover. I cut all the wires and removed the transformer. I removed the bottom cover and it was nearly filled with melted 'stuff'. All the windings measure pretty close to what is on the schematic except for the HV secondary. It's supposed to be 160 ohms and measures 112. The, off center, center tap is supposed to measure 75 ohms to one HV leg and 85 ohms to the other. It measures 64 and 48 respectively. Even though there is continuity, I suspect some of the HV windings are shorted deep inside. I did check, and all the windings are isolated from one another. Not sure that would be the case with operating voltage applied. I'm not even sure I want to test the transformer with a variac. I don't trust that it has severely overheated and won't fail under load. So, I will have to start looking around for a 'parts' chassis either a 39-54 or 39-116. There may be other chassis that use the same transformer, but I'm not aware of any. I will not bother to do anymore work on this chassis as everything hinges on finding and installing a working power transformer. Oh, forgot to mention the safety capacitor is a total short and it's part of a bakelite block. I would try to take a look at the HV secondary, but it's buried underneath the LV filament windings. And before anyone asks, I'm not particularly interested in trying to re-wind the transformer. That's definitely not in my wheelhouse.
If anyone has any suggestions, I'd sure appreciate it!
Thanks all!
Rich