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  • Behringer ultratone k450fx noise issues

    I've got a Behringer ultratone K450fx that seems to have some digital noise(hash) intermittantly after about 30 minutes of play. Turning the FX level to 0 kills the noise . Looking for some suggestions of what I might should be looking for or what to monitor. Behringer+k3000fx.pdf

    thanks, nosaj
    soldering stuff that's broken, breaking stuff that works, Yeah!

  • #2
    Originally posted by nosaj View Post
    I've got a Behringer ultratone K450fx that seems to have some digital noise(hash) intermittantly after about 30 minutes of play. Turning the FX level to 0 kills the noise . Looking for some suggestions of what I might should be looking for or what to monitor. [ATTACH]58566[/ATTACH]

    thanks, nosaj
    Ok probably not the correct schematic, but looking at the fx processor it seems to me I should monitor the 5volt and maybe 15 volt rail an see which one goes wonky and proceed from there.

    nosaj
    soldering stuff that's broken, breaking stuff that works, Yeah!

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    • #3
      Freeze spray? If that stops the noise, then narrow it down. You can use a 3x5 card or even a sheet of paper to form a shield, so you can keep the spray only in certain areas. You can even roll it into a tube and put it around a single part, and blip a little freezit down in there.
      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
        Freeze spray? If that stops the noise, then narrow it down. You can use a 3x5 card or even a sheet of paper to form a shield, so you can keep the spray only in certain areas. You can even roll it into a tube and put it around a single part, and blip a little freezit down in there.
        At the risk being a moron which area might you suggest freezing....definately not the 5 v regulator as that would crack it , it it were over heating , no?

        nosaj
        soldering stuff that's broken, breaking stuff that works, Yeah!

        Comment


        • #5
          I've never cracked a part with freeze spray. Regulators, processors, etc. can get hot. You could start with the finger test first. See what's getting hot.
          "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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          • #6
            I think monitor the supply lines as you mentioned. Look for dropping voltage or ripple when the problem occurs.
            If the supply lines stay solid, no need to freeze the regulators. (though I've done it and never cracked anything either)
            Once supplies are verified good try freezing other chips in FX circuit.
            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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            • #7
              I have never had a part crack from freeze spray. It isn't liquid nitrogen.

              Turning FX to zero kills the noise, so to me, power supply is on all the time, so I am led to suspect the analog FX circuits. I have no idea where they are on a board. So with the thing running and noisy, I just spray the whole darn thing. Does that stop the noise? If so THEN spray smaller areas. We narrow it down to smaller areas until we find something sensitive.


              COuld be signal path, could be power supply. That is what freeze spray is made for. it isn't for cooling your coffee.
              Education is what you're left with after you have forgotten what you have learned.

              Comment


              • #8
                Originally posted by Enzo View Post
                I have never had a part crack from freeze spray. It isn't liquid nitrogen.

                Turning FX to zero kills the noise, so to me, power supply is on all the time, so I am led to suspect the analog FX circuits. I have no idea where they are on a board. So with the thing running and noisy, I just spray the whole darn thing. Does that stop the noise? If so THEN spray smaller areas. We narrow it down to smaller areas until we find something sensitive.


                COuld be signal path, could be power supply. That is what freeze spray is made for. it isn't for cooling your coffee.
                Canned air upside down a suitable sub for freeze spray?
                nosaj
                soldering stuff that's broken, breaking stuff that works, Yeah!

                Comment


                • #9
                  yes, better than nothing.
                  Education is what you're left with after you have forgotten what you have learned.

                  Comment


                  • #10
                    FWIW: I worked on one of those not too long ago with similar symptoms. It ended up not being the effects that were the cause. There was a shorted op amp on one of the inputs sending hash to the effects board. The effects circuit was just doing what it's supposed to do. I'd first make sure all of your inputs work. If they do, then move on to the effects circuit. If not, fix any non working channels first.
                    "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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                    • #11
                      Originally posted by The Dude View Post
                      FWIW: I worked on one of those not too long ago with similar symptoms. It ended up not being the effects that were the cause. There was a shorted op amp on one of the inputs sending hash to the effects board. The effects circuit was just doing what it's supposed to do. I'd first make sure all of your inputs work. If they do, then move on to the effects circuit. If not, fix any non working channels first.
                      All inputs working, once opened I see the board is an lpa145 here be the schematichttps://diagramas.diagramasde.com/ot...PA145_RevG.pdf
                      nosaj
                      soldering stuff that's broken, breaking stuff that works, Yeah!

                      Comment


                      • #12
                        Originally posted by nosaj View Post
                        All inputs working, once opened I see the board is an lpa145 here be the schematichttps://diagramas.diagramasde.com/ot...PA145_RevG.pdf
                        nosaj
                        Replaced c9 and c5 for the 5v supply . Reasoning being based on the k3000 schematics its DSP module used 5v so I inferred the same here. And knowing that Digital requires a much cleaner DC than analog I replaced c9 and c5 and after 4 hrs no electronic hash noises.

                        Case closed only thing is now I have to sell it.

                        nosaj
                        soldering stuff that's broken, breaking stuff that works, Yeah!

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