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Fender Silverface Bassman 10 isn't working. I need help fixing it!

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  • #16
    Does it have the balance type bias pot and is the bias circuit stock? Check the resistors on either side of the bias diode, the bigger 1K sometimes drifts to a higher value.
    Originally posted by Enzo
    I have a sign in my shop that says, "Never think up reasons not to check something."


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    • #17
      It does indeed have the bias balance and is stock except for the components I replaced.

      I've got it running now by paralleling 3 1watt resistors with an end value of 2.07k ohms.

      One of the 7025 tubes is microphonic and the pots are scratchy but it sounds pretty nice.

      I'm contemplating ordering some carbon comp replacement resistors for everything rated at 1watt.
      If I do I'll replace the resistors in the bias area as well.

      All of the resistors I swapped under the doghouse had drifted higher than stock. I replaced those with metal comp.
      I read earlier today that carbon comp resistors add some secondary harmonics and distortion that actually sounds good when they drift under load. Maybe that's an old wives tale though.

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      • #18
        Originally posted by sleepingAwake View Post
        ...I read earlier today that carbon comp resistors add some secondary harmonics and distortion that actually sounds good when they drift under load. Maybe that's an old wives tale though.
        Check out the article "Using the Carbon Comp Resistor for Magic Mojo" at http://www.geofex.com/ and you will learn where carbon comp resistors can make a difference.

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        • #19
          Originally posted by Tom Phillips View Post
          Check out the article "Using the Carbon Comp Resistor for Magic Mojo" at New Page 1 and you will learn where carbon comp resistors can make a difference.
          Lol
          That's what I was reading earlier. Couldn't focus however as the kids were being loud and distracting.
          Bedtime reading for sure.

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          • #20
            2k or 2.7k would probably be OK. Or 2.5k. 2.2k would be better.

            If you plan to order anything, order the proper resistor also.

            7w is an odd size in the parts market, a 10w would be easier to find. Get rid of the cobble job resistor.
            Education is what you're left with after you have forgotten what you have learned.

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            • #21
              Originally posted by Enzo View Post
              2k or 2.7k would probably be OK. Or 2.5k. 2.2k would be better.

              If you plan to order anything, order the proper resistor also.

              7w is an odd size in the parts market, a 10w would be easier to find. Get rid of the cobble job resistor.
              I agree with you.
              I ordered a 10watt 2k2 resistor from digikey earlier today. The cobble job was simply to see where I stood with other aspects of the amp.

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              • #22
                Got a 10 watt 2k2 resistor in from Digikey and threw it in.

                Even though the speakers have holes in them the amp sounds great.

                I'm going to recover it, build a new grille cover and make it look brand new.
                I didnt pay a thing for it so I dont mind dropping a couple hundred on it.

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