Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Hebert on May 25, 2020, 09:10:00 pm
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I attached two images to show what my problem is. They refer to the tremolo section. the schematic shows the middle terminal of a 500k pot connecting to the jack and the end terminal attached to a 100k resister.
but according to the photo the pot has a switch on the back with the middle terminal (not the end terminal) goes off photo to the resistor and the other terminal goes to one of the switch attachment. It also shows the other switch attachment going to the jack. does not seem to mesh with the schematic but I am new to this and there is something I am missing. please help me understand. (this is the foot pedal jack)
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what value is the resistor you describe? the one going to the middle leg?
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The pot is being used as a two terminal variable resistor. And it is in series with a 100K resistor. Makes no difference which pot terminal goes where as long as the pot is still in series with the resistor. It's all good.
And the footswitch jack has a switch terminal that's wired such that when the footswitch is unplugged the jack still provides a ground to allow the trem to work even without a footswitch. The switch on the pot will still turn the trem on/off.
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what value is the resistor you describe? the one going to the middle leg?
100k like the schematic as coming from the end of the pot not the middle
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The pot is being used as a two terminal variable resistor. And it is in series with a 100K resistor. Makes no difference which pot terminal goes where as long as the pot is still in series with the resistor. It's all good.
And the footswitch jack has a switch terminal that's wired such that when the footswitch is unplugged the jack still provides a ground to allow the trem to work even without a footswitch. The switch on the pot will still turn the trem on/off.
thank you, I am going to create a layout for this schematic using the photos I got from videos as a visual aid. I could not have figured out what was going on without the photos.
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Please post your schematic for this amp.
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Please post your schematic for this amp.
here is the full schematic
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what value is the resistor you describe? the one going to the middle leg?
100k like the schematic as coming from the end of the pot not the middle
Then it is wired correctly per Sluckey's explanation.
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what value is the resistor you describe? the one going to the middle leg?
100k like the schematic as coming from the end of the pot not the middle
I trust your expertise and am glad to have the photo to help explain the schematic
Then it is wired correctly per Sluckey's explanation.
Yes
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Hebert, Are you building this model? Or repairing? Or own? I have a non-trem National from the same era. A 1950 National Sportsman - 6SL7 - 6SC7 2x6V6. has two 8" speakers. Nice golden tweed and bird logo on grill. Took me a while to sort it out, as a previous owner's attempted repairs had gone astray. I've thought about building the model you reference as it gets good reviews and I'll likely never see one for a reasonable price!