I have a Sparton 141x radio that I have begun to recap. The problem is, I am new to reading schematics and am not sure where the common ground is on the 10-40-40-50 electrolytic cap. Could someone please explain this to me in basic terms. I know that with metal canister electrolytic caps, the cap usually serves as the ground. The problem is, I am not sure which part to use. Thanks from a newbie

:I have a Sparton 141x radio that I have begun to recap. The problem is, I am new to reading schematics and am not sure where the common ground is on the 10-40-40-50 electrolytic cap. Could someone please explain this to me in basic terms. I know that with metal canister electrolytic caps, the cap usually serves as the ground. The problem is, I am not sure which part to use. Thanks from a newbie

Your new electrolytic should have 4 twist lugs to hole the capacitor into something, usually an insulator, thatthat is mounted to the chassis, usually by two rivets, or screws. One of the twits lugs should wind up connected to the center tap of the high Voltage winding of the power transformer. Your 50uFd./50V. should go the cathode of the 6V6, pin 8. The 40s at 450 should go across the filter choke, and the 10 at 300 should go the the other side of the 2K, R32, I think, the schematic is hard to read. Once again, the negative ground of the capacitor is one (or more) of the lugs you twist to hold it into the mounting plate.
I hope this helps,
Lewis

It is shown clearly here: http://www.nostalgiaair.org/PagesByModel/674/M0018674.pdf

The common negative goes to the chassis, and is usually the metal can, though if you have 5 wires and only need 4 positive wires, one of them could be the negative wire (terminal, etc.). If the can isn't made of metal, then the common negative is surely a wire (or terminal), and if you need 4 positive wires, you must have a 5th wire.

Also, not all radios have the common negative going to the chassis, and not all radios have a multi-section unit with a common negative. Some have a unit with a common positive, and various negative terminals. These are radios where you find the filtering chokes and resistors in the negative part of the supply instead of the positive. All in all it doesn't really matter where the filtering devices are placed. There are even a few radios where the filtering devices are in both parts of the circuit. You must be sure of what you're looking at, though, or you can mess things up (condensers, power supply, etc.).

T.

Thanks everyone for your help. The radio is up and running.

Steve

:It is shown clearly here: http://www.nostalgiaair.org/PagesByModel/674/M0018674.pdf
:
:The common negative goes to the chassis, and is usually the metal can, though if you have 5 wires and only need 4 positive wires, one of them could be the negative wire (terminal, etc.). If the can isn't made of metal, then the common negative is surely a wire (or terminal), and if you need 4 positive wires, you must have a 5th wire.
:
:Also, not all radios have the common negative going to the chassis, and not all radios have a multi-section unit with a common negative. Some have a unit with a common positive, and various negative terminals. These are radios where you find the filtering chokes and resistors in the negative part of the supply instead of the positive. All in all it doesn't really matter where the filtering devices are placed. There are even a few radios where the filtering devices are in both parts of the circuit. You must be sure of what you're looking at, though, or you can mess things up (condensers, power supply, etc.).
:
:T.