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'65 Fender Champ No Power

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  • '65 Fender Champ No Power

    1st thing I notice is it has a 3 prong cord, black wire to fuse, white wire to switch, green wire soldered to chassis. If that is correct wiring, what's a good place to start checking? Thanks.

  • #2
    1 amp slo-blo fuse is good.

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    • #3
      SO far it is a table lamp. Find the primary wires to the power transformer. Is 120vAC reaching them?
      Education is what you're left with after you have forgotten what you have learned.

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      • #4
        Originally posted by Enzo View Post
        SO far it is a table lamp. Find the primary wires to the power transformer. Is 120vAC reaching them?
        Death cap was still wired in. Removed it and power in. Output seems weak. No breakup even at 10.

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        • #5
          Took voltages(photo) anything look off?

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          • #6
            Those Voltages seem like the amp should be working except pin 8 of the 6V6 seems high. With the power OFF, check the resistance to ground on pin 8. Might give a funny reading depending on your meter, but should settle down to something around 470 Ohms.

            Have you tried an external speaker ?
            WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
            REMEMBER: Everybody knows that smokin' ain't allowed in school !

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            • #7
              I think the voltages look extremely high. Even the higher voltage silver face Champs only run about 420Vp with 120V wall outlets. In '65 the Champ is only supposed to have about 350Vp. So it would be a bit higher today, but certainly not 450Vp. No way you can center bias for class A at that voltage with a 6V6.
              Last edited by Chuck H; 04-02-2022, 03:24 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

              "If you're not interested in opinions and the experience of others, why even start a thread?
              You can't just expect consent." Helmholtz

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              • #8
                Originally posted by loudthud View Post
                Those Voltages seem like the amp should be working except pin 8 of the 6V6 seems high. With the power OFF, check the resistance to ground on pin 8. Might give a funny reading depending on your meter, but should settle down to something around 470 Ohms.

                Have you tried an external speaker ?
                With power off, ground to pin 8(6v6)(0.8k ohms). Looks like maybe rectifier tube is lit up more than normal(photo)?

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                • #9
                  Originally posted by ca7922303 View Post

                  With power off, ground to pin 8(6v6)(0.8k ohms). Looks like maybe rectifier tube is lit up more than normal(photo)?
                  Red plating?

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                  • #10
                    Replace the resistor from 6V6 pin 8 to ground. Usually 470 Ohm 1 or 2 Watt.
                    WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
                    REMEMBER: Everybody knows that smokin' ain't allowed in school !

                    Comment


                    • #11
                      Originally posted by loudthud View Post
                      Replace the resistor from 6V6 pin 8 to ground. Usually 470 Ohm 1 or 2 Watt.
                      Appreciate that. Anything to the rectifier tube looking like red plating?

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                      • #12
                        Looks like just normal glow from the filament. No glow from the grey plate structures. The little spec of orange on the 6V6 looks like just a refection.
                        WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
                        REMEMBER: Everybody knows that smokin' ain't allowed in school !

                        Comment


                        • #13
                          Is it a 5Y3 rectifier?

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                          • #14
                            Originally posted by loudthud View Post
                            Those Voltages seem like the amp should be working except pin 8 of the 6V6 seems high. With the power OFF, check the resistance to ground on pin 8. Might give a funny reading depending on your meter, but should settle down to something around 470 Ohms.

                            Have you tried an external speaker ?
                            Tried and external 410 cabinet and it still sounds anemic. Could the high voltage on pin 8 cause output drop? Thanks.

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                            • #15
                              Originally posted by glebert View Post
                              Is it a 5Y3 rectifier?
                              Yes

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