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Alamo Capri tube amp 2560

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  • Alamo Capri tube amp 2560

    Need to know the Input and output on the speaker output transfomer

  • #2
    Output transformer test with ohmmeter
    Input = primary = high resistance
    Output = secondary = low resistance
    Input is connected to the anode tube
    Output is connected to the speaker
    Who does not know and knows that he does not know - teach him Confucius)
    Who knows and does not know that he knows - wake him Confucius)

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    • #3
      Ok what voltage is coming in the input 110 acv ?

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      • #4
        https://music-electronics-forum.com/showthread.php?t=33782
        Alamo Capri Model 2560

        Input 110 acv connects to main (power) transformer T1
        Who does not know and knows that he does not know - teach him Confucius)
        Who knows and does not know that he knows - wake him Confucius)

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        • #5
          These are vague questions. I don't know how much electronics experience you have, but the voltage from your wall can be measured with almost any multi meter and the voltage that your amp requires should be indicated on a schematic or (as you have done here) by doing internet research. vintagekiki was good about linking a relevant thread that includes the schematic (as he often is )

          There is almost sure to be a difference between what's coming out of your wall and what the amp wants. A consequence of the age of the amp vs current power grid standards. A tube amp power transformer is a ratio based component so more volts in will mean more volts out by a factor of the ratio. This is normal and not usually of great consequence. Early 110V power transformer primaries may, however, have an output voltage too high for the filament circuit. That's not an instant explosion sort of problem, but it can reduce tube life.

          Voltages in and out of the output transformer (for the speaker) are more nebulous and depend on what voltages are going into the power transformer as well as specifics of how the amps operating conditions are adjusted. For your amp I would think something like 140VDC to 150VDC measured at the input to the speaker transformer and (with a proper signal put into the amplifier) 4VAC (+/-) going into the speaker.

          Is the amp giving you trouble? If so you should describe the symptoms to us and we can try to help tech support style. ie: Is the unit plugged in
          Last edited by Chuck H; 02-06-2020, 09:59 PM.
          "Take two placebos, works twice as well." Enzo

          "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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          • #6
            This appears that be a series filament “widow maker” type circuit but has an isolation transformer. Don’t see that often. That would be a hard PT to source (if it’s bad) since it has a 90vac tap for the series filaments..

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            • #7
              Originally posted by olddawg View Post
              This appears that be a series filament “widow maker” type circuit but has an isolation transformer. Don’t see that often. That would be a hard PT to source (if it’s bad) since it has a 90vac tap for the series filaments..
              That occurred to me too. We won't know unless JJ checks back in.
              "Take two placebos, works twice as well." Enzo

              "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

              Comment

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