bobins08
Celebrating Life
The turntable is a Yamaha P-751, direct drive automatic.
The project was to replace the phono leads with “better” component video cable. The phono leads are hardwired. While I am inside, I decided to dampen the plinth using plasticine (modeling clay).
The first picture shows the original phono cable wires hardwired to a circuit board.
The second picture is the new component cable and new ground wire. Note the cable, shielding and insulation are much thicker. I added the modeling clay and things seemed pretty straightforward .. until the test.
The result is hum and noise. When the direct drive motor running I hear hum and mid freq noise, like a buzz. Once the stylus drops the music is fine. Better sound than before actually. I have taken the table apart at least 10 times looking for the problem.
At first I realized I forgot the metal shielding cover that goes over the pcb that connects the phono leads. Yes, that will fix! Wrong.
Next I took clay off of the transformer – that did not help. Then I took clay off of the DD motor house – that did not help. Then I did a visual and checked the grounds. Then looked for lose or broken wires and none can be seen.
After that I touched up that solder job and cleaned the connection with isopropyl – that did not help. Then I shortened the right and left channel center conductor wires, minimizing the amount of conductor wire that is not covered with the overbraid and shielding --- no help.
Before I just give up and go back to the old phono cable I am asking anyone who ever did this mod what they think? It appears I created an antenna out of my phono lead. It even causes slight interference on the nearby plasma TV – no turntable has ever done that before in my set up.
Could it be the leads are just not right for the design?
The odd thing is that it sounds good when I play a record. Unfortunately in between the songs, and while the platter is spinning with the stylus up the noise is present.
Thanks, Bob
The project was to replace the phono leads with “better” component video cable. The phono leads are hardwired. While I am inside, I decided to dampen the plinth using plasticine (modeling clay).
The first picture shows the original phono cable wires hardwired to a circuit board.
The second picture is the new component cable and new ground wire. Note the cable, shielding and insulation are much thicker. I added the modeling clay and things seemed pretty straightforward .. until the test.
The result is hum and noise. When the direct drive motor running I hear hum and mid freq noise, like a buzz. Once the stylus drops the music is fine. Better sound than before actually. I have taken the table apart at least 10 times looking for the problem.
At first I realized I forgot the metal shielding cover that goes over the pcb that connects the phono leads. Yes, that will fix! Wrong.
Next I took clay off of the transformer – that did not help. Then I took clay off of the DD motor house – that did not help. Then I did a visual and checked the grounds. Then looked for lose or broken wires and none can be seen.
After that I touched up that solder job and cleaned the connection with isopropyl – that did not help. Then I shortened the right and left channel center conductor wires, minimizing the amount of conductor wire that is not covered with the overbraid and shielding --- no help.
Before I just give up and go back to the old phono cable I am asking anyone who ever did this mod what they think? It appears I created an antenna out of my phono lead. It even causes slight interference on the nearby plasma TV – no turntable has ever done that before in my set up.
Could it be the leads are just not right for the design?
The odd thing is that it sounds good when I play a record. Unfortunately in between the songs, and while the platter is spinning with the stylus up the noise is present.
Thanks, Bob
