[Rbloom659]

Greetings,

After several months of flawless and enjoyable performance from my Cornet 2 purchased used, some issues are cropping up.  Specifically, loud random pops and noticeable break up and distortion.  I am assuming one or more tubes are starting to go bad, and so intend to begin "rolling" them, one at a time.  A quick internet search yields an overwhelming number of options, so I turn to those with some experience in this.  Where to begin, the rectifier?  Are substitutions acceptable for a 5Y3 GT?  My understanding is very limited, but I believe the chief difference between the variations of 12au7, 12ax7, etc. is the output - please feel free to correct and or educate me!  Thanks for any help any one can lend -

Robert

[Yoda]

It is prudent to have a second set of tubes on hand for testing (and over time you'll collect these!) but first check what you have on hand: cables, removing and inserting tubes a few times (in case of oxidation at pins), and double checking your board for burned components or for a cold solder joint(s) and double check voltages while you're there. Your tubes should last a long time - but sometimes you inevitably end up with a bad one.  Look outside of the Cornet to your tonearm, cartridge, and from the cornet to amp. 

 

[Bernie]

Re. looking for cold solder joints, it's a good idea to use a magnifier glass.

Bernie.

[Rbloom659]

A simple tube change out has not resolved the issues, so next step...I am not a tech, so I'm wondering if anyone can recommend a good repair or modification service for this unit.  It would be nice to be able to consider upgrading to a higher level of performance as long as it is being worked on anyway.  There doesn't seem to be anyone in my area (Charleston, SC) or even my state that works on tube gear other than guitar amps.

Robert

[hagtech]

It can also be a bad set of cables. 

jh

[Rbloom659]

OK, I found a local tech who noticed the rectifier socket was loose, and replaced it.  No cold solder joints present, and caps are Multicap type. Previous issues are now greatly improved, but not eliminated completely:  still intermittent pop/snap (reminds of a static discharge, but much louder), fuzzy, distorted sound on some but not all tracks, both channels.  Some sides play perfectly, while others do not.  Very strange.  All cables have been replaced, so the only thing left in the signal chain to analyze is the turntable itself.  Any further thoughts/suggestions are greatly appreciated.

Robert

[poty]

It's very remind me the bad contact in "ground" side of the interconnect (either in the cable or inside the TT). That way the static electricity from vinyl-diamond friction rises up to the level when causes rupture.