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1st amp build, (One Stroke) Volume problem

Discussion in 'Shock Brother's DIY Amps' started by drew1d, Dec 31, 2018.

  1. drew1d

    drew1d Tele-Meister Silver Supporter

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    Hello Amp builders,

    I am in my first amp build currently, and ran into a snag. It is basically a Two Stroke amp. But only one power tube, so a one stroke, as the kids call it these days.
    Turned on, No sparks, no smoke. For some reason it"s really quiet. The volume on the guitar almost cuts it when turned 3/4 on... The voicing switch only works in the Capacitor positions.

    But when I put a pedal in front of it. It roars. I mean, I have to turn the volume on the amp and pedal quite a bit, I'll say a "2" on each and it's louder than the amp alone turned all the way up.

    I figured, it has to be something wired with the input jack. Although I could be quite wrong, any thoughts where to look first?

    Much Thanks - Drew

    Pictures will be forethcoming. Happy New Year.
     
  2. printer2

    printer2 Poster Extraordinaire

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    The input jack soldering or contacts.
     
  3. drew1d

    drew1d Tele-Meister Silver Supporter

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    I have replaced the jack with the same results. Here's an aweful picture. Did I wire the input jack wrong twice?
    IMG_7989.JPG
     
  4. D'tar

    D'tar Friend of Leo's

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    I believe you have the jack terminals incorrect.

    That 68k is coming off the ground terminal

    What does the switch do? Switch bypass caps?
     
  5. drew1d

    drew1d Tele-Meister Silver Supporter

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    Yes 68k ground terminal, I'll take a better picture tomorrow.
    Probably do have the terminals incorrect... The switch is supposed to be a voicing switch between that diminutive 25uf, nothing, behemoth 47uf capacitor.

    I heard on a youtube video of the person making the Twostroke, that the brand of jack he used was oriented in reverse of what the schematic would lend you to believe. I tried reversing the jack, (switching the terminals) but it made no noise after that.
     
    Last edited: Dec 31, 2018
  6. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    Input impedance too low?

    Could you provide a schematic and a layout?

    And some more/better pictures please.
     
    Last edited: Jan 1, 2019
  7. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    Google came up with this:
    Two Stroke Schematic.png

    Is that correct?
     
  8. drew1d

    drew1d Tele-Meister Silver Supporter

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    That's pretty close.

    One Stroke.jpg
     
  9. brogh

    brogh Moderator Staff Member

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    there's also a flying resistor there to the right :eek:
     
  10. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    I think that 68k should not go to ground. It should go to the grid.
     
  11. drew1d

    drew1d Tele-Meister Silver Supporter

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    That sounds right. I did notice two things.
    input section.jpg

    1. Is the "2" lug grounded? everytime I aligator clip it to the ground I get no sound.
    2. I grounded "3" to the case next to it. Does that need to be attacked to the lug?
     
  12. drew1d

    drew1d Tele-Meister Silver Supporter

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    That's my "discharge the lethal capacitors when I work on it" resistor.
     
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  13. brogh

    brogh Moderator Staff Member

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    i think it's the angle of the picture, there's a yellow wire that goes near there , seems to go to pin 3, but form the schematic it should go to pin 2 ?
     
  14. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    You can have a permanent leak resistor, e.g. 220k
     
  15. drew1d

    drew1d Tele-Meister Silver Supporter

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    IMG_7993.JPG
     
  16. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    On the layout it is grounded near pin 2
     
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  17. brogh

    brogh Moderator Staff Member

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    Oh i see that's a far better picture ! :) went trough the schematic and can't see anything wrong, but i'm not so expert, other guys will chime in for sure :)
     
  18. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    That layout drawing is just................bad.

    Why would you try grounding pin 3 of the 12ax7? That arrow says "to board" there as that needs to go to a resistor in order to get some bias voltage/current going.

    As it's drawn, the amp won't work, since as @D'tar mentioned, you're grounding the input. Get rid of that ground connection on pin 2 and switch how the input jack is wired. The 68K resistor needs to come from the hot side contact, not ground side.

    Electrical cord hot wire -> fuse side 1 > fuse side 2 > power switch > one side of PT.
    Neutral wire -> one side of PT.

    It's not drawn like that in either the layout or schematic, but that's how it should be done.

    If you compare the layout to the schematic that @Tom Kamphuys provided you'll see there is no ground on the input (pin2) either. I'd work off that schematic now that you have most of the parts in place since that layout diagram is just wrong.
     
  19. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    It's the ground connection between the 68k and pin 2 (at least)

    It's not present on this layout:
    Hunter_Two_Stroke_Layout-180.JPG
     
    Last edited: Jan 1, 2019
  20. drew1d

    drew1d Tele-Meister Silver Supporter

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    Oddly, it doesn't seem to matter when I "lift" the ground off. It's no difference in volume, a little more buzzy when not attached. I'm starting to think, because there is only one input jack, perhaps it's designed for low impedence feed. And the volume is just a natural result of that, and it's normal for what this amp is...
     
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