03-09-2026, 07:58 PM
I've started to take a look at my C661 chassis.
My first realization was that tube line up was not quite what was in the schematic. It puzzled me for a bit because I had not actually looked closely at the tubes, just took them out and started measuring resistors and transformers. When I got to the area around the 1U5 tube, the chassis wiring was different than the SCHEMATIC. A closer look at the tubes and Philco decided to wire the set with a 1S5 tube instead of the 1U5.
Another interesting item is that apparently Philco originally had a flashlight bulb in the side of the cabinet with a switch. You can just see it in the photo image on the schematic sheet. The set I have does not have that bulb. Probably realized that people would leave the light on and run the battery down pretty regularly. More later...
My first realization was that tube line up was not quite what was in the schematic. It puzzled me for a bit because I had not actually looked closely at the tubes, just took them out and started measuring resistors and transformers. When I got to the area around the 1U5 tube, the chassis wiring was different than the SCHEMATIC. A closer look at the tubes and Philco decided to wire the set with a 1S5 tube instead of the 1U5.
Another interesting item is that apparently Philco originally had a flashlight bulb in the side of the cabinet with a switch. You can just see it in the photo image on the schematic sheet. The set I have does not have that bulb. Probably realized that people would leave the light on and run the battery down pretty regularly. More later...
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
