| Rewiring old Dual [message #13331] |
Mon, 19 March 2007 16:15  |
TOMJ
Messages: 1
Registered: May 2009
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Esquire |
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I have a Dual 1249 turntable that I am working on. I bought it used and it had alot of hum. I pulled out all of the automated stuff, (sometimes it worked, sometimes it didn't) and turned it into a manual table. I'm currently replacing the power cord, and the wiring from the headshell back to phono jacks that I mounted on the back of the TT. On the Original setup, the black grounding wire from the headshell tied into one wire from each cable (blue and green) and then they were grounded to the platform, which is metal. The old power cord from this unit didn't have a ground plug. My question is what's the best way to ground this table? Wire it the same and add a power cord with a ground wire? Or add a ground wire from the platform and run it to my pre-amp? Any help would be appreciated.
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| Re: Rewiring old Dual [message #13332 is a reply to message #13331] |
Mon, 19 March 2007 16:49  |
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Wayne Parham
Messages: 18786
Registered: January 2001
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Illuminati (33rd Degree) |
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Proper grounding is systemic, not just as it relates to one device. What you want is for all devices to be connected to a single ground connection, with each path having very low resistance. The amp or preamp is the natural place for the earth ground to be connected, in my opinion, and all other devices would get their ground connection through it. However, in practice, there are usually several ground paths and this can sometimes lead to a problem. The most common one I see these days is the earth ground connection of the shield from cable TV. When cable TV is connected to an audio system, it should be done through an isolation transformer so it doesn't make a ground connection, usually resulting in a ground loop. Your turntable can be another ground path, so you'll want to check that out. In any case, you'll want the turntable chassis connected to the preamp chassis. Only one of those should be connected to earth ground via the AC power socket.
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