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Chasing down the problem

Couple of nights ago, I was listening to my mono block tube amps and after about ten minutes the right channel goes silent! What the heck!! So begins the search for the culprit...is it upstream of the amps, or is it the right side mono block that has an issue...and what kind of issue.
Luckily, I own another stereo ss amp, so the first thing to do was to hook that up and see if the problem continued. This would eliminate a few pieces of gear as the culprit...basically everything in front of the tube mono blocks...except the connection from the preamp to the mono blocks...the ic’s.
The system played fine with the stereo ss amp in the chain...therefore leading me to believe that the following components were not at fault...1) the front end digital player and the front end turntable set up ( I did play both to be certain) 2) the tube preamp, 3) the connections between these components...speaker cable and ic’s ( I use different ic’s and sc’s to connect the preamp to the ss amp than with the tube amps).
The next day, I hooked up the tube mono blocks again...and this time after making sure that the connections at the amps were tight and that the tubes were all re-seated. Music played again in both channels ---for about twenty minutes! Then the same issue reared its head again, the right channel was silent. Hmm.

Therefore, unless I am wrong, the only two possibilities left are the right tube mono block...or the right ic feeding that mono block from the preamp. My next thing to do was to change the ic’s for another pair ( could have swapped left for right, but since I have other pairs of ic’s that i know are good, i figured why not try this next) Plan being to check the ic’s and then finally start to move tubes from one mono block to the other and vice versa to see if the issue changed channel.
Last night I listened to the same set up but with just the ic’s changed out between the amps and the preamp....and no problem. ( this after a two hour session).
Hopefully, I have identified the issue..would seem that the original right side ic has a iffy connection somewhere ( a lot easier to address than to have to get the mono amp worked on).
Anyone else have a problem like this that took a little ’work’ to identify?

128x128daveyf

Showing 1 response by millercarbon

millercarbon's avatar
millercarbon
12,531 posts
 
Yes. Had a bad solder joint inside the RCA of one interconnect. Very hard to find as it worked fine for so many years, then gradually progressively acting up. Seemed from the beginning to be a connection issue, but exactly where? Intermittent faults are the worst. You get there but slowly. Eventually narrowed it down to inside the plug, and still wasn't sure (just seemed so unlikely!) until taking it apart the wire just pulled right off! Re-soldered, and no problems since.

Yours sounded from the start like another contact problem. In your case parts expand as they heat up, eventually reaching a point where they lose contact. It could be like mine where its inside the IC, where the wires solder to the pins. Or it could be the RCA connection itself. Even a tiny amount of play could be enough for the IC to wiggle just enough for the signal pin, the part that sticks out, to lose contact with the clip, which is inside where you can't see it. 

Not saying its either one, only saying now its narrowed down to a smaller area you have to really zoom in on every little thing going on in that area.
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