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Thread: deeper tremolo in silvertone?

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    deeper tremolo in silvertone?

    My tremolo is not very deep and is only audible in the last 1/3 of the depth pot. I replaced the 6au6 with another supposedly good tube, with no improvement. Would a change in r33 to a smaller value fix it? Or might something else help?
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    Lifetime Member Enzo's Avatar
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    Is C14 healthy? Is there any DC on R33?

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    Thanks Enzo. this is a new build, so c14 should be ok. there is DC on R33. It is swinging between +4v to -3v

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    Lifetime Member Enzo's Avatar
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    That isn't DC, that is the LFO you are seeing. Pull the 6AU6, NOW is there DC on R33?

    Does R33 measure close to 1 meg?

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    I just watched a utube video of a silvertone 1472. Now I'm thinking I may have wired something wrong

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    Quote Originally Posted by Enzo View Post
    That isn't DC, that is the LFO you are seeing. Pull the 6AU6, NOW is there DC on R33?

    Does R33 measure close to 1 meg?
    R33 is almost exactly 1 meg. I'm still getting very small DC without the tube, about +&- .04v

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    I think I've found my error. I have R21 & R22 soldered to pin 5 of the 6v6 tubes.

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    Bent Member Chuck H's Avatar
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    Are you sure? According to the schematic the grid stops (R23, R25) are also 330k like R21, R22.?. Double check that just to be cautious.

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    Quote Originally Posted by Chuck H View Post
    Are you sure? According to the schematic the grid stops (R23, R25) are also 330k like R21, R22.?. Double check that just to be cautious.
    Yeah, I had it wrong. R21 & R22 should be attached to the other end of the grid stops. I had them and the grid stops attached to pin 5. I've moved them now, with no change in the shallow tremolo. Still looking for another error.

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    I wonder if it could be not enough resistance in my grid stoppers. The schematic shows 330k, mine are 1.7k. When I first built the amp, I left the grid stoppers off. They are not on the layout that I found on line, and they are not on the silvertone 1482 schem. which is otherwise very close to the 1472. When I decided to put them in, I chose resistors closer to the ones used in a 5e3 deluxe. I guess it's easy enough to change them, but not tonight.

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    Lifetime Member Enzo's Avatar
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    Stop guessing, find out how the circuit works. Scope it. How much LFO signal is on either side of C14? Then how much at joint between R33 and R34? How much at the Trem FS, and does it vary smoothly?

    R21 and R23 should not affect the amount of LFO signal unless the grids are drawing current.

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    I don't have a scope. Could I measure the LFO with an analogue multi meter?

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    Bent Member Chuck H's Avatar
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    I don't think you could measure it with a DMM. The modulation is slow enough that I don't think the meter would average well. Just bounce around. Plus you cannot see the wave form, which was part of the reasoning.

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    Lifetime Member Enzo's Avatar
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    Maybe a relative reading at the fastest trem speed.

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    Does your meter have a little bargraph on the display like some of the Fluke's have?

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    My power has been out all day, and I still have a tree laying on my roof. Just prior to the tree falling I did something really embarrassingly stupid. I found this on another forum. "1/ Change the R40 680k resistor in serie between the oscillator plate and the trem intensity pot with a jumper.
    This should resolve most of you problem." The thread was about a Vox Cambridge trem, but the REAL problem is that Instead of jumpering the resistor I jumpered the cap. This OBVIOUSLY sent about 300v DC to the grids of the power tubes, burnt the fuse, and apparently damaged something else, because it now JUST blows fuses. Now I just don't have time to look at it.

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    Blows fuses with power tubes removed?

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    Quote Originally Posted by g1 View Post
    Blows fuses with power tubes removed?
    Yes, I'm done working on it for tonight. Not sure what to check when I get back to it. I do have a light bulb limiter.

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    Bent Member Chuck H's Avatar
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    "In fact when I run into problems working on electronic circuirts, there are so many times that when I finally track it down, the source of the problem is located between my soldering iron and my seat." SoulFetish

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    Maybe try replacing the rectifier tube for starters.

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    Quote Originally Posted by g1 View Post
    Maybe try replacing the rectifier tube for starters.
    Ok, I couldn't keep Chuck in suspense any longer. New rectifier has it back the way it was before I went EXTRA stupid.

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    Bent Member Chuck H's Avatar
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    Quote Originally Posted by dmartn149 View Post
    I found this on another forum. "1/ Change the R40 680k resistor in serie between the oscillator plate and the trem intensity pot with a jumper.
    This should resolve most of you problem." The thread was about a Vox Cambridge trem,..
    So in your amp that would be the 1M resistor feeding the 1M intensity pot. Did you try jumpering that resistor or is the amp "back the way it was" circuit wise?

    If you get ample satisfaction from the jumper you might try a smaller value resistor (smaller than 1M anyway) rather than a jumper. And don't sweat the action on only the last third of the intensity pot. Pots of different tapers can be found so that can be addressed later.

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    "In fact when I run into problems working on electronic circuirts, there are so many times that when I finally track it down, the source of the problem is located between my soldering iron and my seat." SoulFetish

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

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    Quote Originally Posted by Chuck H View Post
    So in your amp that would be the 1M resistor feeding the 1M intensity pot. Did you try jumpering that resistor or is the amp "back the way it was" circuit wise?

    If you get ample satisfaction from the jumper you might try a smaller value resistor (smaller than 1M anyway) rather than a jumper. And don't sweat the action on only the last third of the intensity pot. Pots of different tapers can be found so that can be addressed later.
    Thanks Chuck. Yes jumpering that R gives plenty of trem. I'll try different R values there till I'm happy with the max. I'm not worried about the pot taper.

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