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Replacing tonearm cable - Dual 604

I gave my son his grandfather’s old Dual 604 turntable. But there’s a short (hum) in one of the channels. I’m not sure where the short is (it changes sides when I swap the connections on the back of his receiver). I suppose it could be in the cartridge which is also at least 40 years old. It works for a while then the short appears. I’m thinking of replacing the tonearm cable first but am wondering if this is doable on this table given the construction. I’m not sure the tonearm can be easily removed but I’m handy and there’s not much to lose at this point.

Anyone have thoughts on this? I haven’t gotten into it yet but it doesn’t look nearly as simple as on my Clearaudio Innovation table. 

Other things I should try first? 

TIA

mgrif104

 

mgrif104
mgrif104 OP
574 posts
 

@jasonbourne71 

I was certainly planning on it, but wanted to address the hum/short. Are you thinking it’s in the cartridge?  

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jasonbourne71
1,873 posts
 

I don't think it's the tonearm wiring. Check to make sure that the phono cable has a good ground connection to the receiver. There should be a separate ground wire from the tonearm.

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jasonbourne71
1,873 posts
 

Corrosion on the cartridge signal pins/tonearm leads is suspect given the age. Sometimes just making/breaking these connections will fix the problem.

cleeds
6,601 posts
 

I agree that checking ground and making sure all connections are clean and tight are the first steps to take. This doesn't sound like a short. To test the pickup arm wiring you can reverse the connections at the cartridge pins.

mgrif104 OP
574 posts
 

Thanks @jasonbourne71 and ​​​​@cleeds  - I’ll give that a try. I had already fiddled with and ensured the connection to the back of the receiver (including ground) was good. It’s definitely 60 hz hum as it’s intermittent and I know what that sounds like. But i was thinking it was the tonearm wire where it connects to a junction box of sorts underneath the deck of the table. Much easier if it’s at/in the cartridge. 

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