Welcome, Guest. Please login or register.

October 29, 2020, 09:24:19 PM

Login with username, password and session length

Recent Posts

 

Author Topic: Peavey Classic 30 Output Tube blows  (Read 8791 times)

Enzo

  • Legendary
  • ******
  • Posts: 1979
  • Chip Points: 214
    • View Profile
Re: Peavey Classic 30 Output Tube blows
« Reply #15 on: June 15, 2015, 03:52:02 PM »
it will crack free, get under it with a small screwdriver or something.

There is glue, there is silicone, and there is hot melt.  I don't know which you face.  Hot melt will turn brittle and shatter easily if you hit it with freeze spray.  Nothing dissolves silicone, so trim it off with an Xacto knife.  And contact cement or rubber based glue usually can be slit with a blade or just popped free.

Hawk

  • Elite
  • ****
  • Posts: 223
  • Chip Points: 3
    • View Profile
Re: Peavey Classic 30 Output Tube blows
« Reply #16 on: June 16, 2015, 07:46:16 AM »
Thanks Enzo. I've included a photo. Looks like glue to me, but I'm no expert.

Hawk

  • Elite
  • ****
  • Posts: 223
  • Chip Points: 3
    • View Profile
Re: Peavey Classic 30 Output Tube blows
« Reply #17 on: June 16, 2015, 08:00:15 AM »
screwdriver worked :tu:

phatt

  • Legendary
  • ******
  • Posts: 2142
  • Chip Points: 261
    • View Profile
Re: Peavey Classic 30 Output Tube blows
« Reply #18 on: June 16, 2015, 08:12:35 AM »
Yep looks like hot melt glue which is usually not a problem, as you found out.
Re the high bias; maybe check for faults around R63 and R64, maybe something has lost connection there.
Phil.

Hawk

  • Elite
  • ****
  • Posts: 223
  • Chip Points: 3
    • View Profile
Re: Peavey Classic 30 Output Tube blows
« Reply #19 on: June 17, 2015, 09:57:25 AM »
Okay, with tubes in voltages check out at screen, plate, about 31 ma per tube. Checked all the power supply caps, ESR check good. Checked power supply resistors. But there are some loud intermitant squeals about every 50 or sixty seconds, as if a little elf is inside the amp using a tiny drill--haha! Sometimes it's a littles squeal but then it stops, and the odd time a few small pops. But when I chopstick test this amp, almost everywhere I touch, including transformer secondary wires, it makes lots of noise as if something isn't grounded,.  or the grounding is poor somewhere. When I knock the chassis the sound gets worse then stops, now its just pulsating wierd squeaking sounds. Ran a signal through the amp and the scope showed it as good.

Oscillations? Ground issues? ???

Hawk

  • Elite
  • ****
  • Posts: 223
  • Chip Points: 3
    • View Profile
Re: Peavey Classic 30 Output Tube blows
« Reply #20 on: June 17, 2015, 03:46:39 PM »
Okay, found that one of the output tubes was acting up. No pops, nothing!!! I chopstick components, tap chassis, fiddle with tranformer wires and no nasty sounds! I'm going to let the amp run for awhile. Fingers crossed!!

phatt

  • Legendary
  • ******
  • Posts: 2142
  • Chip Points: 261
    • View Profile
Re: Peavey Classic 30 Output Tube blows
« Reply #21 on: June 19, 2015, 07:33:00 AM »
Good work :tu:, but maybe check the bias voltage . If it's still at -21Volts the amp will be cold biased and won't be working at optimum.
Phil.

Hawk

  • Elite
  • ****
  • Posts: 223
  • Chip Points: 3
    • View Profile
Re: Peavey Classic 30 Output Tube blows
« Reply #22 on: June 19, 2015, 10:27:36 AM »
The bias, at it turns out, is -18 V, once I inserted the tubes, so yes, a little cooler than factory specs. Someone before me changed the bias resistors. Still sounds good, see what my friend says when he tries out his amp. I can always change them back to factory specs. Thanks Phil!