I got my Yamaha YP-700 quite recently and have undertaken a number of maintenance activities. There was a slight noise coming from the turntable. First I thought that maybe the noise was picked up by a fairly long and cheapo RCA-cable from my phono preamp to the speakers but this was not the case. Got a good piece of advice on a Finnish Vintage Audio Facebook group about a possible grounding issue. According to the friendly expert who advised me the same approach has been taken on many older turntables and I would suspect that many of the Yamaha YP-700 related turntables (e.g. YP-500, YP-701, Sonab 85S) may have a similar earth connection solution as mine had, i.e. all the grounding poles (signal ground and chassis/tonearm ground are interconnected by a wire). My turntable had the old European style DIN connector - can't tell if the connection is the same for those units that came with RCA-connectors. This approach in grounding will cause hum in the signal.
The fix is to cut the wire that connects the furthermost connection poles and the center pole (see the attached photo, the bare twisted wire is the culprit). So, just cut it on both sides of the center pole and remove. I also added a separate wire to the center pole of the connection bar and ran it to the ground connector of my phono preamp. Now the turntable is really quiet. Sharing this hoping that others can also get rid of unwanted noise and enjoy these quite magnificent turntables to the full. To get to the connector, you will need to remove the bottom plate of the turntable. The connector bar is protected by a metal case. Beware of the screws, they are really soft and get ruined very easily because the screws have got stuck. If they don't want to unscrew, you may want to apply some heat on them to try and get them loose. I had to drill one of the screws and got it out using pliers.
The fix is to cut the wire that connects the furthermost connection poles and the center pole (see the attached photo, the bare twisted wire is the culprit). So, just cut it on both sides of the center pole and remove. I also added a separate wire to the center pole of the connection bar and ran it to the ground connector of my phono preamp. Now the turntable is really quiet. Sharing this hoping that others can also get rid of unwanted noise and enjoy these quite magnificent turntables to the full. To get to the connector, you will need to remove the bottom plate of the turntable. The connector bar is protected by a metal case. Beware of the screws, they are really soft and get ruined very easily because the screws have got stuck. If they don't want to unscrew, you may want to apply some heat on them to try and get them loose. I had to drill one of the screws and got it out using pliers.
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