Champ Kit build, no sound

Discussion in 'Amp Tech Center' started by goforit, May 9, 2020.

  1. goforit

    goforit TDPRI Member

    Age:
    21
    Posts:
    11
    Joined:
    May 9, 2020
    Location:
    Orlando
    I just finished up my first champ kit and have a problem. There is no sound. When i initially tested my build i got a loud ear piercing squeal, Which i read may be due to positive feedback and could be fixed by switching output transformer primaries. After switching them, the squeal went away but i have no sound. Some voltage readings i took are as follows:


    12ax7
    pin1: 161
    pin3: 1.3
    pin6: 161
    pin8: 1.2

    6v6
    pin2: 16
    pin5: 320
    pin6: 285

    5y3
    pin1: 330

    the B+ voltages read 330, 285, and 245

    i see a common problem is a missing ground between the 22kohm resistor connecting the 8uf filter caps and the 100k ohm resistors that lead to the 12ax7, but I do have voltage there. I know it could be a number of different things, where should i start?
     
  2. Peegoo

    Peegoo Friend of Leo's

    Posts:
    4,913
    Joined:
    Oct 11, 2019
    Location:
    Wyoming panhandle
    1. Discharge all electrolytic caps.

    2. Take a good look at your electrolytics to make sure they're in the right way 'round.

    3. Red-ink all the wires on the schematic or layout diagram. This means to go wire by wire in the amp, look at each one, and then draw over it with the red pen on the layout to account for it being connected to the correct terminations.

    I do the red ink thing as I build. It has prevented goofs (I used to get 'em) over the last 10 or so amp builds I've done.
     
    ce24, Treehouse and Strebs like this.
  3. FenderLover

    FenderLover Poster Extraordinaire

    Posts:
    5,605
    Joined:
    Jun 11, 2009
    Location:
    Minnesota
    Check your output stage wiring. Pin 2 is a heater, so 16V is not right. Pin 5 is Grid1, so 320V is not right.

    For the 6V6 measure pins 3, 4, 8 (plate, G2, cathode).
     
  4. dan40

    dan40 Tele-Afflicted

    Posts:
    1,919
    Joined:
    Aug 19, 2015
    Location:
    Richmond Va
    When you took your voltage measurements, did you hear a pop through the speaker whenever you touched your probe tip to the plate leads of each tube?
     
  5. goforit

    goforit TDPRI Member

    Age:
    21
    Posts:
    11
    Joined:
    May 9, 2020
    Location:
    Orlando
    @FenderLover

    I'm sorry, I made a mistake on the PIN numbers of the 6v6.

    pin2 measures 0 (not 16)
    pin3 is 320
    pin4 280
    pin8 16v
     
  6. goforit

    goforit TDPRI Member

    Age:
    21
    Posts:
    11
    Joined:
    May 9, 2020
    Location:
    Orlando
    @dan40 I made a little 4ohm dummy load out of leftover resistors I have lying around. so no actual speaker is connected.
     
  7. dan40

    dan40 Tele-Afflicted

    Posts:
    1,919
    Joined:
    Aug 19, 2015
    Location:
    Richmond Va
    The "pop" test is a great diagnostic tool to find out whether or not the amp is passing signal to the speaker. Starting at the power tube, work your way back through the circuit. If the plate of the 6v6 pops but the 12ax7 does not, you have just narrowed down the area of the circuit that is not working properly. If every stage produces a pop chances are the input jack is wired wrong.
     
    Treehouse and D'tar like this.
  8. goforit

    goforit TDPRI Member

    Age:
    21
    Posts:
    11
    Joined:
    May 9, 2020
    Location:
    Orlando
    @dan40 Okay I will try it out. Thank you for your help!
     
  9. D'tar

    D'tar Friend of Leo's

    Posts:
    3,020
    Joined:
    Jan 11, 2013
    Location:
    WNY
    Pictures of the input jacks and the pop test
     
  10. goforit

    goforit TDPRI Member

    Age:
    21
    Posts:
    11
    Joined:
    May 9, 2020
    Location:
    Orlando
    Here are pictures of the input jack. I just tried the pop test and did not get popping anywhere throughout the amp. what does that indicate?
     

    Attached Files:

  11. dan40

    dan40 Tele-Afflicted

    Posts:
    1,919
    Joined:
    Aug 19, 2015
    Location:
    Richmond Va
    Could be an output jack wiring problem. Are you using one output jack like the original or did you go with two jacks as seen in some of the other Fender's? Some models such as the Deluxe have a main jack and an extension cabinet jack. Plugging into the ext jack only would yield no sound at all. Original Champs only have a single jack so this could not be the problem if you stayed true to the originals.
     
  12. goforit

    goforit TDPRI Member

    Age:
    21
    Posts:
    11
    Joined:
    May 9, 2020
    Location:
    Orlando
    @dan40

    I only have one output jack. could it be something to do with the output transformer?
     
  13. D'tar

    D'tar Friend of Leo's

    Posts:
    3,020
    Joined:
    Jan 11, 2013
    Location:
    WNY
    You removed the dummy load and have the speaker plugged in right? Your voltages suggest your tubes are conducting. A few more pictures would be good. Lets see the output jacks too.

    On your inputs make sure the 1M leg is not touching the shunt, it looks real close but may just be the photo.
     
    dan40 and muchxs like this.
  14. muchxs

    muchxs Doctor of Teleocity

    Posts:
    13,171
    Joined:
    Aug 14, 2004
    Location:
    New England
    ^ ^ ^ ^ ^

    First thing I looked at was your input jacks. That's always going to be a quiet amp, as- is. It looks like your input goes to ground.

    Wire it up with one input and your 1 meg grid leak. You'll have sound if nothing else is wrong.
     
    Jlwctn and dan40 like this.
  15. goforit

    goforit TDPRI Member

    Age:
    21
    Posts:
    11
    Joined:
    May 9, 2020
    Location:
    Orlando
    @muchxs so the input jacks are wired incorrectly?

    would you mind explaining how they are incorrect? I dont really understand. should the second input not be grounded through the preamp bus? thank you for your help
     
  16. goforit

    goforit TDPRI Member

    Age:
    21
    Posts:
    11
    Joined:
    May 9, 2020
    Location:
    Orlando
    @D'tar here is a picture of the output jack. Thank you for your help
     

    Attached Files:

  17. D'tar

    D'tar Friend of Leo's

    Posts:
    3,020
    Joined:
    Jan 11, 2013
    Location:
    WNY
    They are correct as long as they aren't making unwanted contact. The green arrow looks like the leg is close to shorting on the shunt. The red circle around the other shunt looks close to the first jacks ground ring. Maybe give it a little bend away from the other jack

    20200509_221826.jpg
     
    Last edited: May 9, 2020
  18. goforit

    goforit TDPRI Member

    Age:
    21
    Posts:
    11
    Joined:
    May 9, 2020
    Location:
    Orlando
    @D'tar here is a better photo of the input jacks. do they look okay?
     

    Attached Files:

  19. D'tar

    D'tar Friend of Leo's

    Posts:
    3,020
    Joined:
    Jan 11, 2013
    Location:
    WNY
    Yep.

    The pop may only appear as a scratching sound on the 6v6 plate or grid. Should be more noticeable on the grids of the 12ax. Once you are operational ypu may want to shorten some wires up.
     
  20. D'tar

    D'tar Friend of Leo's

    Posts:
    3,020
    Joined:
    Jan 11, 2013
    Location:
    WNY
    Make sure the unused output tap is not grounded.
     
    dan40 likes this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.