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Crown Xti 1000 - No power

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    Crown Xti 1000 - No power

    Symptoms when I got it was RT6 Was getting hot was getting thermal error lights
    Now I am not getting any lights RT6 has stopped getting hot.

    Replaced C196 - 35v 200uf
    Replaced u14 - TL494
    Replaced R370, R371, R372, R73 - 48.7K with 47K resistors as I was told these would be fine.

    I measure voltages at c195 and get 9.5 volts it says in the manuals the voltage at this cap is meant to be over 35v.

    Anyone else know what else I should be checking on this amp.
    Attached Files
    Last edited by Amraks; 08-17-2019, 10:38 PM.

    #2
    Re: Crown Xti 1000 - No power

    The only C195 I see is a 0.1µf/25v on page 6 connected to V_BULKRTN
    Attached Files
    Last edited by R_J; 08-17-2019, 10:36 PM.

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      #3
      Re: Crown Xti 1000 - No power

      Originally posted by R_J View Post
      The only C195 I see is a 0.1µf/25v on page 6 connected to V_BULKRTN
      C196 Edited.
      Sorry about that had the wife in the ear while typing this.

      Comment


        #4
        Re: Crown Xti 1000 - No power

        Where is C196? the pdf is not searchable

        Comment


          #5
          Re: Crown Xti 1000 - No power

          Its off the transformer with 2 diodes on the v_kstart

          Comment


            #6
            Re: Crown Xti 1000 - No power

            You could have defective zener diodes D28,D29, V_KSTART (32v) should be there when the AC_SW (S7) is pressed, Then the smps should start and supply the 30 volts.
            If RT6 was getting hot and the amp was on, I suspect that the relay contacts in K1 are burnt and open. Once the amp is turned on, K1 should short out RT6 At this point RT6 could also be open
            Last edited by R_J; 08-17-2019, 11:14 PM.

            Comment


              #7
              Re: Crown Xti 1000 - No power

              funny that you say this now I measured the ground to to + side of c196 and get 0.00v in diode mode
              So that probably make sense.

              Comment


                #8
                Re: Crown Xti 1000 - No power

                If you measure a short across C196, check for a shorted D26. I don't see how you are measuring a short when earlier you had 9 volts across it?
                Last edited by R_J; 08-17-2019, 11:20 PM.

                Comment


                  #9
                  Re: Crown Xti 1000 - No power

                  I lifted one of the legs of D26 and if I remember correctly around about 0.400v on the multimeter.

                  Comment


                    #10
                    Re: Crown Xti 1000 - No power

                    Originally posted by R_J View Post
                    If you measure a short across C196, check for a shorted D26. I don't see how you are measuring a short when earlier you had 9 volts across it?
                    I will recheck this to see what results I am getting.

                    Comment


                      #11
                      Re: Crown Xti 1000 - No power

                      Check your voltage across +/- of D24 bridge rectifier, it should be around 300 vdc If its not RT6 could be open.
                      You might also want to check R374,R378 & D31
                      You need that +30V_CTRL because it is the supply for the +15V_CTRL which is needed for the VCC of U14 and U18 smps driver
                      Last edited by R_J; 08-17-2019, 11:40 PM.

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                        #12
                        Re: Crown Xti 1000 - No power

                        I defiantly have them voltages at the bridge.

                        Forgot to add I have changed R374 and R378.

                        D31 I haven't checked.

                        Comment


                          #13
                          Re: Crown Xti 1000 - No power

                          What are you using for ground when you check this voltage? you should be using V_BLKRTN or D24 (-) If you used chassis as the ground the voltages won't be right.
                          Just a note on RT6, it will and should get warm/hot it is a ptc thermistor.
                          Last edited by R_J; 08-18-2019, 09:08 AM.

                          Comment


                            #14
                            Re: Crown Xti 1000 - No power

                            I have been using BLKRTN as ground.

                            As for D24 its got 302vdc there.

                            RT6 doesn't get hot after changing u14 which this chip is typical to go and cause not turning on faults.
                            As well as changing them resistors and that cap.
                            is it possible u14 could be faulty but then again I should have correct voltages before that.

                            Comment


                              #15
                              Re: Crown Xti 1000 - No power

                              Have you checked any of the voltages on U14? Do you have VCC on pin 12? The ic will not work without VCC +15V_CTRL
                              If you have 300vdc on V_BULK, then it will be on one end of R374, then about(145v?) on R378 and then 16 vdc on D31.
                              You should have 300VDC on one end of R370, then less (135v?) on R371, and then 32vdc on D28 (two 16 volt zeners in series = 32v) This 32 volts MUST be there or nothing works. (I guessed at the 135/145 voltages)

                              Re check your solder connections on U14, maybe there is a short between pins or a pin is not making connection?
                              You should reinstall the original U14.

                              The amp was turning on before but there was likely an issue with K1 contacts not closing and all the current was flowing through RT6 instead of being shorted by the relay.
                              Attached Files
                              Last edited by R_J; 08-19-2019, 08:55 PM.

                              Comment


                                #16
                                Re: Crown Xti 1000 - No power

                                On u14 pin 12 9.20v - not enough.to run that chip
                                voltage on r378 is 12v - 13v

                                voltages on them resistors starting from v_bulk side of them

                                start of (r370 - 310v) (r371 - 160v) v_kstart 9.83v

                                Comment


                                  #17
                                  Re: Crown Xti 1000 - No power

                                  There's not much in that circuit, something is causing V_KSTART to be 10 volts instead of 32v
                                  Also D31 is a 16v zener and you are getting 12v on it. Q39,40,41 are acting like voltage regulators for the +15V_CTRL, D31 sets the voltage, +30v is the input to the regulators.
                                  Is the circuit board double sided? if it is check that you did'nt damage a feedthrough when you changed C196.

                                  If you are getting 9.83 on V_KSTART, that will be on D27 anode, that would give about 9.2 volts on the +30V_CTRL. So the Q39,40,41 must be turned on (or shorted) and supplying that 9.2 to the +15V_CTRL

                                  You can lift one end of D27 and see if your V_KSTARTcomes up to 32v, You could lift R375 to see if you get 16v on D31
                                  Last edited by R_J; 08-19-2019, 09:34 PM.

                                  Comment


                                    #18
                                    Re: Crown Xti 1000 - No power

                                    I put the original chip back down and its doing the same thing where rt6 instantly heats up

                                    No shorts as I am doing this under a microscope for the tiny components

                                    Comment


                                      #19
                                      Re: Crown Xti 1000 - No power

                                      So now the power supply is drawing current again, but the K1 relay is not being energized to short RT6, What is the V_BULK voltage now?
                                      So what are the voltages on V_KSTART and +15V_CTRL
                                      Also are you getting +30 & -30 voltage on the transformer secondary, On C35 or C46 (measured to chassis)

                                      U14 should be driving the U18 gate driverthat will be driving the two fets Q28 & Q31, I would guess they are ok, They will drive HB_OUT which drives the T1 transformer, if that circuit is working you should have the secondary voltages.
                                      The +30 volts is required for the relay supply (via Q16) to A1, Then if the micro U1 is working it should output the SOFT_START signal to Q17 which turns on Q18 energizing K1 which will short out RT6.
                                      Last edited by R_J; 08-19-2019, 10:05 PM.

                                      Comment


                                        #20
                                        Re: Crown Xti 1000 - No power

                                        V_KStart keeps rising up to 24v and drops back.

                                        I would say them U14 chips where fake ebay ones.

                                        you mentioned relay?

                                        Comment

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