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amp makes popping noises when i prod power tube

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  • amp makes popping noises when i prod power tube

    Fender Hot Rod Deville, 2x12. Maybe 5 years old.

    lately when i play, i get weird popping and crackling noises at random times. always when i hit a note or a chord.

    people say to check the tubes, 1 by 1, right to left (looking from the back). every time i pull a tube, the signal just dies. no hum. should i do this with the amp completely on? ive been doing it in stand-by mode.

    when the amp is on, i can induce the popping noise by poking the right-hand power tube (looking from the back).

    anyone got any ideas? i'd rather not have to pay the 70/hr to have this fixed in my local shop.

    thanks!

    mike

  • #2
    If it were me, I'd throw in a new set of output tubes with a new phase inverter tube and move it. It sounds like an OT going to me. After 5 years, it's very plausible.

    But every reply will have a different opinion we'll soon see.
    <div class="signaturecontainer">Yamaha FGX720SCA<br />
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    • #3
      If it were me, I'd throw in a new set of output tubes with a new phase inverter tube and move it. It sounds like an OT going to me. After 5 years, it's very plausible.

      But every reply will have a different opinion we'll soon see.


      new tubes isn't a bad idea. could you explain output tubes and phase inverter tubes? i'm not familiar with this stuff. i see 2 big ones and 3 little ones

      any other ideas, folks?

      Comment


      • #4
        Hot Rod Deville Manual
        Page 7 shows the tube layout

        Comment


        • #5
          okay so i popped the back off so i could see the circuit board.

          above the output tubes, there is a circle of solder points for the tube pins.

          when i tap that output tube, i can see a blue light flashing at one of the solder points on the circuit board!!!

          if this is just a bad tube, i'll replace it. if it's a bad solder point, i can do that myself as well.

          suggestions?

          edit: the popping crackling noise occurs when this blue flashing light is visible. it's like... arcing electricity.... this is bad haha.

          Comment


          • #6
            Bad solder joints on the tube socket pins.

            The #1 problem with Hot Rod amps.

            #2 is the power supply for the channel switching.

            #3 is catastrophic failure.

            I guess you got lucky.
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            • #7
              Wow, the number of results for searching "Hot Rod Deville cold solder joint" is pretty impressive, unfortunately. Seems like a flaw that needs to be addressed.

              Cold solder joints on the tube sockets is mentioned a lot, which is what you are describing.

              If you are techy, I'd say look up these problems and address them now. Or get the amp into a tech familiar with the amp and it's flaws that will treat you right.

              In short, you may not have bad tubes, yet, if you address those issues.
              <div class="signaturecontainer">Yamaha FGX720SCA<br />
              Fender Stratocaster<br />
              Mesa Express 5:25<br />
              Roland Micro Cube<br />
              <a href="http://riderinfo.com/" target="_blank">Bikers and Bands</a><br />
              <div align="right">For entertainment purposes only.</div></div>

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              • #8
                Wow, the number of results for searching "Hot Rod Deville cold solder joint" is pretty impressive, unfortunately. Seems like a flaw that needs to be addressed.

                Cold solder joints on the tube sockets is mentioned a lot, which is what you are describing.

                If you are techy, I'd say look up these problems and address them now. Or get the amp into a tech familiar with the amp and it's flaws that will treat you right.

                In short, you may not have bad tubes, yet, if you address those issues.


                My $0.02.

                Most of those cold solder joints were not bad when they left the factory. Lots of heat - especially for people who actually use these outside of their bedrooms, plus vibration from the speaker, and relatively high mass from the power tubes = bad solder joints.

                Design flaw. One of many in the hot rod series.
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                • #9
                  "Wife makes plopping noises when I prod her pooper tube."

                  The parody I was afraid to make.

                  Comment


                  • #10

                    people say to check the tubes, 1 by 1, right to left (looking from the back). every time i pull a tube, the signal just dies. no hum. should i do this with the amp completely on? ive been doing it in stand-by mode.

                    mike


                    Btw, from what I know you should definitely NOT pull tubes while the amp is on under any operation and the amp should not function (and may get ****************ed up) if you try and play without the tubes in (there are exceptions, ala pulling 2 tubes in some model Marshalls (outside or inside not next to each other).

                    A few things you should know that folks haven't directly mentioned-- the small tubes are the preamp tubes, the bigger ones are the power amp tubes. Generally, "checking tubes" means a couple of things-- tap them with a pencil, eraser side. If you hear any high pitch tones or pops that tube is probably microphonic or shot. The other thing is to replace the preamp tubes one at a time and see what happens-- preamp tubes do not have to be "matched".

                    Power tubes should be matched (in most amps) so you have to change whole sets to check what's up there.

                    In your case, however, it does sound like a cold solder joint at the tube socket.

                    Oh, and the phase inverted is the preamp tube nearest the power amp in most layouts (though you should check yours). Generally this may be considered a part of your power amp (though as I understand it it sits more "between" the two) but it's the same tube type as a preamp tube (in most cases). Playing around with that tube and V1 (the first tube after the input) generally has the largest effect on tone depending on how you run your amp and design.

                    Good luck.
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                    • #11
                      okay guys, you are going to be very disappointed in me now.

                      i decided to swap the power tubes, to see if it was the tube or the socket.

                      in the first place, only the right tube was finicky. after switching them, i got popping noises and NO output.

                      if i sort of wiggled the tubes left or right in their sockets, i could get signal to come in. now, however, i'm getting nothing. no output. i wiggle the tubes and nothing happens.

                      >.<

                      Comment


                      • #12
                        when i tap that output tube, i can see a blue light flashing at one of the solder points on the circuit board!!!

                        edit: the popping crackling noise occurs when this blue flashing light is visible. it's like... arcing electricity.... this is bad haha.



                        Those tube sockets are mounted on the PCB, so any wiggling of the tubes (even putting in or removing them) places undue strain on the solder joints. It appears that you have a broken solder joint(s) that needs to be fixed.

                        Comment


                        • #13
                          Bad solder joints on the tube socket pins.

                          The #1 problem with Hot Rod amps.



                          I'm no amp expert, but having cheap plastic tube sockets (and cheap plastic input jacks) attached to the PCB is terrible idea. I'd bet that the Hot Rod amps would have a better reputation if Fender would just have all jacks chassis-mounted!

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                          • #14
                            alright, well. i have a bs in electrical engr, and i've done lots of solder work, so i'm inclined to check this out myself.... but i've heard horror stories about people getting nailed by high voltage capacitors. anyone have any tips or resources about working on a fender deluxe?

                            Comment


                            • #15
                              okay guys, you are going to be very disappointed in me now.

                              i decided to swap the power tubes, to see if it was the tube or the socket.

                              in the first place, only the right tube was finicky. after switching them, i got popping noises and NO output.

                              if i sort of wiggled the tubes left or right in their sockets, i could get signal to come in. now, however, i'm getting nothing. no output. i wiggle the tubes and nothing happens.



                              And so it begins. Be prepared for problem #3.
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