I found an old record player in a dump, and I'm trying to fix it up, though I only have a passing knowledge of electronics and audio. There are two shielded cables coming out of the internal pre-amp, with the shielding of one of the cables also connected to a pin on the pre-amp, but the plugs have been cut off the ends of these cables. It also has no ground cable.

How should I connect RCA plugs on to these cables: what connects to the ring, and what to the tip?

Do I need a ground cable? What do I connect it to?


closed as off-topic by Eugene Sh., Nick Alexeev Nov 20 '17 at 18:09

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  • \$\begingroup\$ Find a ground point. Measure impedances using a live test, not just sticking the DMM between them. The low impedances are ground (ring), the high(er) are signal (tip). \$\endgroup\$ – Ignacio Vazquez-Abrams Nov 20 '17 at 17:57
  • \$\begingroup\$ @IgnacioVazquez-Abrams: with two plugs (for left and right), I have two rings and two tips, but only three outputs from the pre-amp. Do I connect the ground output from the pre-amp (which is connected to the shielding of one of the cables) to both rings? \$\endgroup\$ – Max Nov 20 '17 at 18:08
  • \$\begingroup\$ It is entirely possible for both connectors to share the same ground connection. \$\endgroup\$ – Ignacio Vazquez-Abrams Nov 20 '17 at 18:09

Whenever attaching an RCA plug (or any coaxial plug) to a shielded cable, always connect the center conductor of the cable to the center pin of the plug, and the shield of the cable to the outer shell of the plug. Other configurations are almost never what you want.

You do not need a separate ground wire because there is an internal pre-amp providing a low impedance output, so special configurations of ground wiring are not necessary — the cable shields are all the ground path needed.

You will need to figure out which channel is left and which is right if you want your RCA plugs properly color coded — I don't know of a good way to do that short of swapping them if you get it wrong, or tracing wires all the way back to the cartridge, or making a temporary alligator clip connection and listening to that. (A continuity test will not work by itself because of the pre-amp.)


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