scottosan
Well-known member
Went to my favorite Japanese 2nd hand store at lunch. I see an Orange TH30C marked as junk. As usual, check to see if I get any sound, even his from the speaker. I get some his, so I know the OT is likely good. I try the comtrols on both channels and the signal intermittent and notes fizzling out and it get much worse in less than a minute . It’s priced at ¥22000 ($138). I also notice it’s loaded with a Celestine G12H 70th Anniversary. Alright, done deal.
Get it home, take the back off so I could see the tubes amd fire it up to see if I could visual observe any tubes flaking out. Within a minute I see one of the El84s redplating. Okay. Not problem. Pop the chassis, find and test the screen resistors and cathode bias resistors, all good
This amp has a 2/4 tube switch this disable 2 of the 4 output tube and switch you tap from the 16 ohm OT lead to the 8ohm lead to compensated for the impedance change from removing 2 tunes. I know the bad 2 was in then remaining sockets of the 2/4 switch so I pull the bad tube and a second tube and move a good tube to the socket where the bad tube was.
Turn it on and all is good in life. Confirmed it was just the tube. Got a new quad that should be here next week.
Get it home, take the back off so I could see the tubes amd fire it up to see if I could visual observe any tubes flaking out. Within a minute I see one of the El84s redplating. Okay. Not problem. Pop the chassis, find and test the screen resistors and cathode bias resistors, all good
This amp has a 2/4 tube switch this disable 2 of the 4 output tube and switch you tap from the 16 ohm OT lead to the 8ohm lead to compensated for the impedance change from removing 2 tunes. I know the bad 2 was in then remaining sockets of the 2/4 switch so I pull the bad tube and a second tube and move a good tube to the socket where the bad tube was.
Turn it on and all is good in life. Confirmed it was just the tube. Got a new quad that should be here next week.