04-07-2013, 06:27 PM
OK, here's where I need an expert opinion.
I don't seem to have the 2nd Det / 1st Audio hookup as it shown in the schematic for 38-15, both 121 and 124.
Actually both of those are referred to in the same schematic so I figured there is no schematic difference except small things like Grounding one speaker voice coil end in 121.
However, both show that D1 and D2 pins of the 75 tube are together.
In my case only one, namely D2, is connected the way it is shown.
The D1 is disconnected from them and then connected the way it is in this below diagram.
It goes to the cap #6 via what seems to be a 1M resistor and also to the Cathode via another 1M resistor.
Does anyone know if the real hookup like this existed or is it an "improvement" someone did?
I don't seem to have the 2nd Det / 1st Audio hookup as it shown in the schematic for 38-15, both 121 and 124.
Actually both of those are referred to in the same schematic so I figured there is no schematic difference except small things like Grounding one speaker voice coil end in 121.
However, both show that D1 and D2 pins of the 75 tube are together.
In my case only one, namely D2, is connected the way it is shown.
The D1 is disconnected from them and then connected the way it is in this below diagram.
It goes to the cap #6 via what seems to be a 1M resistor and also to the Cathode via another 1M resistor.
Does anyone know if the real hookup like this existed or is it an "improvement" someone did?
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
