03-20-2021, 08:34 PM
So.
What I had found is pretty hideous
Whoever connected the phonograph to the radio did a heck of a job in the literal sense of the word "heck".
The schematic has the 4-pin phono connector that provides 115V (Line and Neutral) to the motor and 6V for the lamp from the same winding that has the rest of the filaments of the tubes except the phono amp tube, one of the latter ones being also the Chassis GND.
The V-M phonograph has the ON-OFF-REJECT switch that has two wires connected to Line (Hot) at its output. The 1st goes obviously to the motor and the other probably went to some sort of light which had to be 115V light.
So.
The Nicola Tesla who did the connections :
1 . Connected the 115V L and N, L going through the switch.
2. The switch output 115V, the second wire he routed back to the Chassis GND.
3. The 6V lamp wire he routed via a capacitor as the GND for the motor.
DO I hear "Wow!".
But wait! It worked! Because....yes, because there was no GND or when it was it was floating due to the isolating transformer.
Once plugged into the outlet, it blew.
So. I left the motor wires, I connected the Chassis to the motor frame, and I fully disconnected 6V as it is not used and the second 115V wire after the switch as, again, it is not used either.
No blow-ups anymore, everything works.
It plays, and with the new needle will probably play that much better.
Now, the hum.
The GND did attenuate the hum, but at the maximum volume with the PHONO ON, it is still heard.
I changed the wire that comes from the volume pot for the shielded wire that I grounded to the chassis and that attenuated it some more, but not all the way.
I see the place it originates from (output of the phono amp) but it comes from some other place than the input as when I short the plug or even the tube's pin to the GND (which is 1/2 inch away) it still hums.
Will try some more things tomorrow, though it is acceptable. It would be more acceptable had it been the original player but the thing is, due to the impedance mismatch the volume is not very loud and it could benefit from the maximum loudness except that the hum could be heard when the player is not playing.
What I had found is pretty hideous
Whoever connected the phonograph to the radio did a heck of a job in the literal sense of the word "heck".
The schematic has the 4-pin phono connector that provides 115V (Line and Neutral) to the motor and 6V for the lamp from the same winding that has the rest of the filaments of the tubes except the phono amp tube, one of the latter ones being also the Chassis GND.
The V-M phonograph has the ON-OFF-REJECT switch that has two wires connected to Line (Hot) at its output. The 1st goes obviously to the motor and the other probably went to some sort of light which had to be 115V light.
So.
The Nicola Tesla who did the connections :
1 . Connected the 115V L and N, L going through the switch.
2. The switch output 115V, the second wire he routed back to the Chassis GND.
3. The 6V lamp wire he routed via a capacitor as the GND for the motor.
DO I hear "Wow!".
But wait! It worked! Because....yes, because there was no GND or when it was it was floating due to the isolating transformer.
Once plugged into the outlet, it blew.
So. I left the motor wires, I connected the Chassis to the motor frame, and I fully disconnected 6V as it is not used and the second 115V wire after the switch as, again, it is not used either.
No blow-ups anymore, everything works.
It plays, and with the new needle will probably play that much better.
Now, the hum.
The GND did attenuate the hum, but at the maximum volume with the PHONO ON, it is still heard.
I changed the wire that comes from the volume pot for the shielded wire that I grounded to the chassis and that attenuated it some more, but not all the way.
I see the place it originates from (output of the phono amp) but it comes from some other place than the input as when I short the plug or even the tube's pin to the GND (which is 1/2 inch away) it still hums.
Will try some more things tomorrow, though it is acceptable. It would be more acceptable had it been the original player but the thing is, due to the impedance mismatch the volume is not very loud and it could benefit from the maximum loudness except that the hum could be heard when the player is not playing.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
