Announcement

Collapse
No announcement yet.

Denon 4308CI NO AUDIO

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Denon 4308CI NO AUDIO

    I picked up a Denon 4308CI cheap and the unit powers on fine but I have no audio output. I tore the unit down and found on the audio unit board a bad cap and a blown transistor. C507 100uF 50V and TR501 KTA1268. The KTA1268 is not available so I need to find something equivalent.

    https://cdn.badcaps-static.com/pdfs/...fffd426395.pdf

    This one is close but not exact.


    Any recomendations?
    Attached Files
    Last edited by ngen33r; 08-12-2018, 09:28 PM.

    #2
    Re: Denon 4308CI NO AUDIO

    992 is only rated at 50mA Ic, 1268 is rated at 100mA.
    Never stop learning
    Basic LCD TV and Monitor troubleshooting guides.
    http://www.badcaps.net/forum/showthr...956#post305956

    Voltage Regulator (LDO) testing:
    http://www.badcaps.net/forum/showthr...999#post300999

    Inverter testing using old CFL:
    http://www.badcaps.net/forum/showthr...er+testing+cfl

    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
    http://s807.photobucket.com/user/budm/library/

    TV Factory reset codes listing:
    http://www.badcaps.net/forum/showthread.php?t=24809

    Comment


      #3
      Re: Denon 4308CI NO AUDIO

      I cannot find an exact match at digikey or mouser.

      I can go 1/2 the rated voltage


      or

      Higher voltage and less gain


      Or I can try my chances on eBay transistors which are probably fake.

      Comment


        #4
        Re: Denon 4308CI NO AUDIO

        You could also contact Digikey, and they may suggest something.

        Comment


          #5
          Re: Denon 4308CI NO AUDIO

          Originally posted by tibimakai View Post
          You could also contact Digikey, and they may suggest something.
          Never thought to do that. Thank You

          Comment


            #6
            Re: Denon 4308CI NO AUDIO

            They recommended these:

            https://www.digikey.com/product-deta...X795A-ND/92573

            Parts ordered let's see what happens. I am replacing all of the caps in that section as one of them ruptured, which most likely killed the transistor with noise the other parts seem to test ok.

            Comment


              #7
              Re: Denon 4308CI NO AUDIO

              I recapped that section of the board and replaced the PNP with

              The transistor blew again when powered on so another problem exists.

              Comment


                #8
                Re: Denon 4308CI NO AUDIO

                Any ideas on this one because these look like the muting circuits they shouldn't have excessive current flowing through them.

                Comment


                  #9
                  Re: Denon 4308CI NO AUDIO

                  Hard to tell without the service manual. The partial schematic you posted does'nt even show C507.
                  Last edited by R_J; 08-23-2018, 08:55 PM.

                  Comment


                    #10
                    Re: Denon 4308CI NO AUDIO

                    I found a schematic, I take it the transistor shorted? if you remove it, what voltage do you get on TR501 collector (C503) it should be around -7 volts. also check the base voltage (d511 anode)
                    What was wrong with C507? You should check the voltage on each side of C507, you should have -12v on the negative and possibly +5v on the positive lead.

                    (Page169)
                    Last edited by R_J; 08-23-2018, 11:34 PM.

                    Comment


                      #11
                      Re: Denon 4308CI NO AUDIO

                      C507 was blistered and leaking, could be an un-related problem. I checked the voltage rails and everything seems to be good there.

                      I will test the things you listed tomorrow.

                      Comment


                        #12
                        Re: Denon 4308CI NO AUDIO

                        More problems found:
                        B - 34V
                        C - 10V
                        E - 61V

                        I unplugged CW155 & CW068
                        B - 100mV
                        C - -3.88V
                        E - 475mV

                        More checking shows both transistors (TR630 TR631) on the 5V supply are shorted and I have a blown audio output. IC301 is also fried. My guess is the blown output is the cause. I am not sure that I can find a replacement for the outputs. IC301 might also be impossible to source. I am not sure if I trust eBay parts but that may be my only option. I have the service manual but it is too large to post.
                        Last edited by ngen33r; 08-29-2018, 08:32 PM.

                        Comment


                          #13
                          Re: Denon 4308CI NO AUDIO

                          Must have been a big boom.
                          Attached Files

                          Comment


                            #14
                            Re: Denon 4308CI NO AUDIO

                            Trace Repaired:
                            Attached Files

                            Comment


                              #15
                              Re: Denon 4308CI NO AUDIO

                              Have you checked the main amplifier transistors? Usually when they short they take some smaller transistors also.

                              Comment


                                #16
                                Re: Denon 4308CI NO AUDIO

                                http://pacificsemi.com/search.php
                                SAP15N
                                Last edited by tibimakai; 09-02-2018, 10:39 AM.

                                Comment


                                  #17
                                  Re: Denon 4308CI NO AUDIO

                                  Mains were blown. I also found a bad diode.
                                  https://www.digikey.com/product-deta...03P-ND/3661836

                                  Comment

                                  Working...
                                  X