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Unknow component in a power amp

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  • Unknow component in a power amp

    Hi all, I need your help, I have a power amplifier a subwoofer (AXYS Uniamp 700), which has no voltage on the diode bridge, the only component that seems not right is this: KVR 10-471, according to the pcb is a NTC but can't find information about it, if anyone can offer any type of information you would appreciate with well cold beers you come for Spain!
    Thank You!
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  • #2
    I thought it was a varistor, 10mm 470V.
    Originally posted by Enzo
    I have a sign in my shop that says, "Never think up reasons not to check something."


    Comment


    • #3
      Yeah, it is an NTC varistor.
      The 'NTC' implies that its a type Negative Temperature Coefficient.
      It will start at a high resistance & as it warms up the resistance will drop.

      Comment


      • #4
        So are we all off to Spain then for some beer G1 and JP Bass ?

        I put KVR 10-471 in google first "hit" =

        Vatronics MYG GENERAL PURPOSE VARISTORS

        http://www.vatronics.com/Upfiles/down/201171885402.pdf


        Nominal Varsitor Voltage at 1mA DC 470

        Rated Voltage (V)
        ACrms 300
        DC 385

        Clamping Voltage (V)
        810 - 775

        Comment


        • #5
          Just beer?

          I'd ask for some Paella:

          Juan Manuel Fahey

          Comment


          • #6
            I believe Spain's Paella is wurst after the bailout...

            Comment


            • #7
              THe NTC marking on the board is a little confusing. An NTC usually goes in line with the supply and a Varistor is a shunt device that behaves somewhat like a pair of opposing-series Zeners, or a gas-discharge tube. AN NTC anti-surge protector has a low resistance (just a few ohms) that falls as it warms up and acts as a soft-start. A Varistor does not conduct under normal operating voltages but will do so when a particular threshold is reached. Sometimes they're placed after a fuse so that the fuse deliberately blows under higher-voltage conditions.

              They do get tired if the breakdown voltage is repeatedly approached and can fail on their own, sometimes with no other fault present.

              Comment


              • #8
                Mick is right.
                So I guess the question is, is it connected parallel to a source or in series with whatever load there is?
                If parallel, certainly is a MOV; Series, most certainly an NTC of some sort.

                Comment


                • #9
                  Originally posted by Mick Bailey View Post
                  THe NTC marking on the board is a little confusing.
                  There is also a marking on the board right by there that says Var2. So I'm wondering if they use one or the other?
                  Originally posted by Enzo
                  I have a sign in my shop that says, "Never think up reasons not to check something."


                  Comment


                  • #10
                    That's the first thing I did yesterday. But it's a Varistor no a ntc, Thanks
                    Originally posted by oc disorder View Post
                    So are we all off to Spain then for some beer G1 and JP Bass ?

                    I put KVR 10-471 in google first "hit" =

                    Vatronics MYG GENERAL PURPOSE VARISTORS

                    http://www.vatronics.com/Upfiles/down/201171885402.pdf


                    Nominal Varsitor Voltage at 1mA DC 470

                    Rated Voltage (V)
                    ACrms 300
                    DC 385

                    Clamping Voltage (V)
                    810 - 775

                    Comment


                    • #11
                      Yes, the NTC is connected in series with the diode bridge, the question is what kind of ntc is? Thanks!
                      Originally posted by diydidi View Post
                      Mick is right.
                      So I guess the question is, is it connected parallel to a source or in series with whatever load there is?
                      If parallel, certainly is a MOV; Series, most certainly an NTC of some sort.

                      Comment


                      • #12
                        That's not paella, The "real paella" is this

                        Originally posted by tedmich View Post
                        I believe Spain's Paella is wurst after the bailout...

                        Comment


                        • #13
                          I am surprised at the confusion, NTC1 is the part designation for a NTC Thermistor that is in series with the load, as a slow start mechanism. Very many amps have them and they are not that uncommon to go bad.

                          Comment


                          • #14
                            Originally posted by km6xz View Post
                            I am surprised at the confusion, NTC1 is the part designation for a NTC Thermistor that is in series with the load, as a slow start mechanism. Very many amps have them and they are not that uncommon to go bad.
                            I think the confusion arises from it looking like a MOV, being spec'd as a MOV, but being marked NTC and connected in series.

                            Comment


                            • #15
                              Spec's as a MOV? It says 470 ohms on it, it has a board designation of NTC1. The original probably works, not burned as is the normal failure mode, just the lead broke possibly due to vibration.

                              Comment

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