[EthanH]

Hi, I was hoping I could get some feedback/diagnosis on a problem with my Cayin TA30.  Any help at all would be really appreciated.

Tonight while listening to music the right speaker started distorting like crazy - I'm sure many of you know the score: crackles, pops, and the woofer bouncing around like a sub in an spl contest.  Before I turned the amp off I noticed what appeared to be a bright spark/flicker near the plate of the right 12AU7.  So far I've done the following diagnostic stuff:

-I took the 12AU7 out and replaced it with a spare - silence from right speaker. 

-I switched the 12AX7s around - silence from right speaker. 

-I replaced the right power tubes - silence from right speaker. 

-I hooked the right speaker up to another amp - the right speaker plays normally.

Needless to say I am totally bummed.    Hoping it is just a blown fuse, but am a little apprehensive about opening the amplifier up.  I'm open to any suggestions/guesses as to what the issue might be.  I was hoping someone here might be familiar with the Cayin TA30.

Also, I posted in mid-atlantic circle for recommendations for a reputable tube repair service in South Jersey/Philadelphia, but if anyone else has suggestions here I would really appreciate it.

Thanks all

[JakeJ]

Well you've isolated it to the Cayin so that eliminates some guess work.  Likely a part failure.  If you are going to open the chassis but are unfamiliar with tube amps then please use great caution.  There can be high voltages still present.  You could just take the bottom cover off and look for obviously burned parts (which I think you will see).  Was there any smoke or a burning smell from the amp when this failure occurred?  If you do pop it open take a picture and post it here so we can see too.

Best of luck and be careful.
Jake

Just a few from the "Audio Repair Companies" thread:
http://musictechnology.com/ in Springfield, VA
http://www.analogique.com/ in NYC
http://www.sound-smith.com/ in Peekskill, NY
http://www.sgcustomsound.com/ in Douglaston, NY

[sfox7076]

I would look for a raised/swelling cap or a burned resistor.  Likely a cooked resistor from a red playing 12au7.  Never had a 12au do that.  But, well, I have never used them for more than a preamp tube. 

[raindance]

Sounds like a coupling capacitor failure between the 12au7 and one of the power tubes. Probably took out a fuse. Do you see any blue glow inside the el34 tubes on the non working channel?