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Hoffman Amps Forum image Author Topic: Valco tremotone 1224 question  (Read 2757 times)

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Offline Hebert

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Valco tremotone 1224 question
« on: May 25, 2020, 09:10:00 pm »
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)

Offline vampwizzard

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Re: Valco tremotone 1224 question
« Reply #1 on: May 25, 2020, 10:14:35 pm »
what value is the resistor you describe?  the one going to the middle leg?

Offline sluckey

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Re: Valco tremotone 1224 question
« Reply #2 on: May 25, 2020, 10:48:17 pm »
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.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Hebert

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Re: Valco tremotone 1224 question
« Reply #3 on: May 25, 2020, 11:03:51 pm »
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

Offline Hebert

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Re: Valco tremotone 1224 question
« Reply #4 on: May 25, 2020, 11:05:41 pm »
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.

Offline sluckey

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Re: Valco tremotone 1224 question
« Reply #5 on: May 26, 2020, 07:05:43 am »
Please post your schematic for this amp.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Hebert

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Re: Valco tremotone 1224 question
« Reply #6 on: May 26, 2020, 07:40:11 am »
Please post your schematic for this amp.

here is the full schematic

Offline vampwizzard

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Re: Valco tremotone 1224 question
« Reply #7 on: May 26, 2020, 08:27:13 am »
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.

Offline Hebert

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Re: Valco tremotone 1224 question
« Reply #8 on: May 26, 2020, 01:02:52 pm »
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
« Last Edit: May 26, 2020, 02:00:19 pm by Hebert »

Offline bmccowan

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Re: Valco tremotone 1224 question
« Reply #9 on: May 26, 2020, 01:17:07 pm »
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!
Mac
“To my surprise, when I opened my eyes, I was the victim of a great compromise.”
John Prine

 


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