06-21-2021, 02:41 PM
Your chassis would seem to be an interim production between the two schematics. This isn't unusual.
1) You are correct.
2) In the late production, the cathode of the 78 goes to ground through the phono switch. The original had it connected to a network. I suspect that somewhere in between they modified it to go to ground.
3) As the 6A7 cathode is going to ground through a 300 ohm resistor while late production goes directly. As with the other modifications, this was most likely an interim change while the engineering department was tweaking the performance specs.
1) You are correct.
2) In the late production, the cathode of the 78 goes to ground through the phono switch. The original had it connected to a network. I suspect that somewhere in between they modified it to go to ground.
3) As the 6A7 cathode is going to ground through a 300 ohm resistor while late production goes directly. As with the other modifications, this was most likely an interim change while the engineering department was tweaking the performance specs.
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