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is there a ghost in my machine?

Hi, all, I've been reviving a vintage stereo setup and can't seem to isolate the problem with the right channel speakers; the right channel fades out and dies completely but only under certain circumstances.
 Here are the details:  I've got a just-renovated Linn LP12, and a Conrad-Johnson PV1 which just came back from getting its tubes checked and pots cleaned (because I wasn't getting sound in the right speakers) . I've got a Carver Power amp and Peter Sequerra bookshelf speakers. I played a couple of albums and for about an hour or so I got sound out of both speakers, then the right channel faded and died. 

I wasn't sure if the problem was the Carver or the CJ, so I used a 3.5mm to RCA jack and played my Bose radio with just the Carver and the left and right channel kept going with no fadeout or drop for three hours...so I don't think the problem is the power amp, or the speakers. 

I tried the turntable again with the CJ and got sound from both speakers for about fifteen minutes and then the right channel faded out again. Switched cables on the Carver and both speakers worked for a few minutes and then the left speaker dropped out. 

I"m not sure if there's something going on with the CJ right channel output or the Turntable output - I just had them both reconditioned, too!! It's a real head fake because the sound doesn't drop out right away.
As I see it:
- I could try another RCA cable for the CJ to the Carver  and see if that allows the turntable to play both channels for an extended period of time OR=try adding a tuner to the CJ to see if the CJ plays both right and left channels for radio ...that would tell me the CJ is fine and the problem is in the right channel in the turntable somehow. The Linn cartridge, I was told, is fine; however I've also heard-that the cartridge head has right and left channel wiring and maybe that's the issue. 
I haven't had problems with sound in both channels bypassing the CJ and the turntable and playing a radio and an Mp3 with just the Carver.  
I'm open to suggestions.  It's interesting that I got a good two hours with the CJ and the Linn from both speakers when the turntable and the CJ hadn't been used for weeks..  Do I need to put a fan in the stereo cabinet? 



avenueb
millercarbon's avatar
millercarbon
12,531 posts
 
Also if you narrow it down to the preamp the next step is to try and see if it happens with another input. This will narrow it down to the phono stage or the pre-amp section. 

Tubes can go at any time so it does no good to guess and assume, you simply perform each test to methodically narrow it down by a process of elimination.
mijostyn's avatar
mijostyn
8,570 posts
 
Avenueb you are having a problem with the Right channel of the CJ.
Something is going south as the unit warms up. If you are uncomfortable with a soldering Iron other than swapping tubes you will need to take it to a tech who has the appropriate equipment to trace it down. There are several things this could be including a bad tube even if they were tested. I am sure the tube fellow did not warm the tube up for 15 minutes before he tested it. 
fuzztone's avatar
fuzztone
5,633 posts
 
Fans are cheap insurance..Of course you don't HAVE to do anything.
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lewm
13,168 posts
 
Like MC says, keep swapping leads, all the way back to the cartridge itself if necessary, in order to differentiate between a problem in the CJ, phono only or linestage, and then the cartridge and related ICs. Localizing the problem is what you must do first, before anyone outside your listening room can help.

this is a complete shot in the dark, and it is no substitute for doing the work that MC suggested, but I have to wonder about the grip of the wiring on the cartridge pins. If it comes down to that, check those wire clips on the cartridge pins. But first do the homework, is my advice.
asvjerry's avatar
asvjerry
4,705 posts
 
Seems a 'heat' issue with a soldered joint or a tube....doesn't occur immediately, but as current flows through it, it warms up and fails.  It's just real slow about it.
A fan likely wouldn't fix it, but can't hurt as a future addition.

Doesn't make sense at the TT or the cart, and the thermodynamics of a stylus would seem a real stretch.

Esoteric gear, esoteric issues....

Good luck, J
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