gofar99 Messages: 1947 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
Hi Everyone, This is something I posted on another site but thought I would share it with you all.
Thwarted by the blob
It got me, made me frustrated. It made me waste a lot of time. For several days it confounded me. I looked everywhere for the problem. I checked each connection, each cable, tested all the tubes. I took apart the phono preamp at least 10 times. It always checked out fine on the bench, but not in the system. Ugh, double ugh. It did give me the opportunity to upgrade some internal wiring and interconnects though. Not the problem. What was happening was that the one phono preamp would stop putting out sound on one channel at random intervals in the system. All the other gear attached (4 amps, the line stage, the crossover, the other phono preamp, CD, and speakers) checked out fine and behaved like expected. The preamp always worked on the bench. So I figured the problem had to be somewhere else. Wrong, double wrong. Finally I spied the problem, a small blob of solder that was stuck on the bottom side of the left channel output jack. On the bench the cables put just enough side pressure on the jack to keep it from shorting out. In the system because of the way the cables were arranged the pressure was less. So at random intervals it would short out. Now all is fine. The blob has gone to blob Valhalla. Or considering my less polite thoughts on the issue some place much warmer.
Wayne Parham Messages: 18782 Registered: January 2001
Illuminati (33rd Degree)
Oh, yeah, I just love those sorts of problems. Super weird ones. Even weirder than a cold solder joint - sounds like yours was a mechanical problem caused by the physical size of the solder material causing interference with another electrical conductor, squeezing it into an unwanted connection. Nice find!
Rusty Messages: 1184 Registered: May 2018 Location: Kansas City Missouri
Illuminati (3rd Degree)
Beware of The Blob, it creeps
And leaps and glides and slides
Across the floor
Right through the door
And all around the wall
A splotch, a blotch
Be careful of The Blob
Written By Burt Bacharach of all people for the movie. But, your dilemma would have driven me insane. Those little drops of solder are to be given great deference. And removed, destroyed, annihilated at all cost. Thanks for sharing a great cautionary tale.
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It did give me the opportunity to upgrade some internal wiring and interconnects though. 
Not the problem. What was happening was that the one phono preamp would stop putting out sound on one channel at random intervals in the system. All the other gear attached (4 amps, the line stage, the crossover, the other phono preamp, CD, and speakers) checked out fine and behaved like expected. The preamp always worked on the bench. So I figured the problem had to be somewhere else. Wrong, double wrong. Finally I spied the problem, a small blob of solder that was stuck on the bottom side of the left channel output jack. On the bench the cables put just enough side pressure on the jack to keep it from shorting out. 
In the system because of the way the cables were arranged the pressure was less. So at random intervals it would short out. Now all is fine. The blob has gone to blob Valhalla. Or considering my less polite thoughts on the issue some place much warmer. 
