Welcome, Guest. Please login or register.

September 18, 2020, 10:51:09 AM

Login with username, password and session length

Recent Posts

 

Author Topic: Red Knob Fender Champ 12  (Read 6127 times)

dogbox

  • Regular
  • **
  • Posts: 23
  • Chip Points: 0
    • View Profile
Red Knob Fender Champ 12
« on: August 31, 2010, 07:59:38 PM »
http://www.champamp.net/images/champ_12_schem.gif
Hi,
hoping someone can shed some light..
I powered this up the other day, the light comes on but the sound isn't there. There is a really weak signal still coming through - to give an idea how low the volume I can hear the strings being strummed.

I checked the fuse -in tact.
Does this sound like a valve has blown?? I would like to try and fix myself, but have limited knowledge of amps (done pedals and kits) no real experience with mains voltages/valve amps

Any suggestions appreciated on how to tackle this.
cheers
newb

J M Fahey

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 4142
  • Chip Points: 429
    • View Profile
Re: Red Knob Fender Champ 12
« Reply #1 on: September 01, 2010, 12:35:18 AM »
Start by plugging some audio in the CD inputs, tell what happens.

dogbox

  • Regular
  • **
  • Posts: 23
  • Chip Points: 0
    • View Profile
Re: Red Knob Fender Champ 12
« Reply #2 on: September 02, 2010, 02:50:15 AM »
Start by plugging some audio in the CD inputs, tell what happens.

Hi JM,

Tried that on your suggestion - so far no sound!! Hooked an RCA cable from amp to a ghetto blaster -  switched on the ghetto blaster, then switched on the amp-waited..no sound output from the amp.

What next???

thanks for the assist.
cheers
Steve

J M Fahey

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 4142
  • Chip Points: 429
    • View Profile
Re: Red Knob Fender Champ 12
« Reply #3 on: September 02, 2010, 09:12:24 PM »
Ok, we'll go backwards.
AMPLIFIER OFF AND UNPLUGGED ALL NIGHT
Start by testing the speaker.
1) Unplug its cables, get a battery (9V or 1.5V), touch the negative to the negative terminal , the positive to the other one, it should click.
2) If good, hook it as normal, follow green and black wires leaving output transformer, touch their ends briefly with your battery terminals, speaker should click, although somewhat fainter.
3) If good, follow red and blue wires from output transformer and touch its ends to + and - battery terminals.
Although fainter, you should still hear some click.
A 9V battery will give a louder click than an 1.5V one.
Post results, and meanwhile get a multimeter.
Be careful.
« Last Edit: September 03, 2010, 05:02:15 AM by J M Fahey »