Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TerryD on October 24, 2011, 06:36:29 am
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I pulled a stereo tube amp from a large cabinet...probably from the early sixties. I want to make a little platform to use with my Klipsch chorus II stereo speakers.
Two 12 ax7s in the preamp
Each amp for the left and right speakers has one 5Y3 GT, one 12 Ax7 and two el84s
Are there "must replace" parts in these? The two large caps with cardboard on the containers...both 10 MFD and 400 volts actually "look" in good shape. There is no bubbling on either end.
The left amp isn't quite working now but I think thats a loose connection or faulty tube. There is green corrosion on one of the 12ax7 pins. Thanks ahead for any help. Terry
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Obviously clean up the corrosion. Light em up with a lamp limiter. If it acts right, go to normal power. If it hums, replace the electrolytics. I'm a big believer in, "if it;s not broken, don't fix it" but replacing old electrolytics is typically a good practice. Check for proper fusing and modernize the grounding. Oh... another easy check for electrolytics, light it up with all the tubes except for the rectifier. Measure the DC voltage. Disconnect power and the voltage should remain and fall slow. If it dives immediately towards zero,it's cap time.
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light it up with all the tubes except for the rectifier.
I bet you really meant to say "light it up with all the tubes removed except for the rectifier. "
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light it up with all the tubes except for the rectifier.
I bet you really meant to say "light it up with all the tubes removed except for the rectifier. "
DOH! :BangHead: