Beocenter 9300 No Life – almost

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Home Forums Product Discussion & Questions BeoCenter Beocenter 9300 No Life – almost

Viewing 19 posts - 1 through 19 (of 19 total)
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  • #54194
    filip_kbh
    BRONZE Member
      • Copenhagen
      • Topics Started 13
      • Total Posts 149

      I just picked up a BC9300 for 15 GBP, advertised as defect but with a relay clicking.

      True enough – I just connected it to mains, and I hear a click from a relay. Other than that, there is no stand-by light. I have opened the unit (the glass panel was of course loose, so I took that off), and I see no obvious signs. Is there a known problem, like e.g. cracked solder joints around a certain capacitor that I should look for, or should I start by seeing if I have the correct voltages as per the service manual?

      #54197
      filip_kbh
      BRONZE Member
        • Copenhagen
        • Topics Started 13
        • Total Posts 149

        Is the relay on the standby board supposed to click? Because mine doesn’t say a click.

        #54198
        filip_kbh
        BRONZE Member
          • Copenhagen
          • Topics Started 13
          • Total Posts 149

          .

          #54199
          filip_kbh
          BRONZE Member
            • Copenhagen
            • Topics Started 13
            • Total Posts 149

            All fuses were good.

            #54200
            filip_kbh
            BRONZE Member
              • Copenhagen
              • Topics Started 13
              • Total Posts 149

              I guess I should have started by checking the battery:

              IMG_0055IMG_0056IMG_0057IMG_0058

              There was only one trace that was broken, so I fixed that. Those batteries are a ticking time bomb ?

               

               

              #54196
              filip_kbh
              BRONZE Member
                • Copenhagen
                • Topics Started 13
                • Total Posts 149

                I have the correct voltages from the transformer. On the standby board I also have correct voltages except for P90 pin 1. It’s supposed to be 7.8V as I read the schematic (it says ‘7V8 unregulated’) but I measure approx. 24V.

                #54195
                auric
                BRONZE Member
                  • Topics Started 14
                  • Total Posts 83

                  Check the fuses behind the cover where power cord goes into the unit.

                  But always inquire why the fuses blew in the first place!

                  #54205
                  filip_kbh
                  BRONZE Member
                    • Copenhagen
                    • Topics Started 13
                    • Total Posts 149

                    When the motor is spinning, pin 3 gives 15V – but it is not every time the plug is plugged in that the motor will start.

                    #54206
                    filip_kbh
                    BRONZE Member
                      • Copenhagen
                      • Topics Started 13
                      • Total Posts 149

                      I think there’s still an issue with the micro processor board. I realise I made a mistake repairing the dead track but now that it’s fixed to the right points, there is no relay clicking. I did experience that some of the panels lit up but I don’t know what I touched prior to that. Argh.

                      #54201
                      Madskp
                      GOLD Member
                        • Denmark
                        • Topics Started 35
                        • Total Posts 833

                        Yeah those batteries can make a mess.

                        I don’t know if it is just the picture, but it looks like there is a crack in the diode D5

                        #54202
                        Guy
                        Moderator
                          • Warwickshire, UK
                          • Topics Started 14
                          • Total Posts 1,238

                          I have just replaced the battery in the electronically similar BC2300 – see thread here:

                          https://beoworld.org/forums/topic/beosound-ouverture-cd-not-working/page/2/#post-29315

                          But after seeing your picture I may speed up battery replacement in my other similar aged B&O devices.

                          #54203
                          filip_kbh
                          BRONZE Member
                            • Copenhagen
                            • Topics Started 13
                            • Total Posts 149

                            Yeah those batteries can make a mess. I don’t know if it is just the picture, but it looks like there is a crack in the diode D5

                            Indeed, it does look that in the pictures. I have just re-opened it and tested D5, and there is no crack, and it measures fine. But thank you – because I originally forgot to test that diode. Now, off to my favourite all too expensive diode pusher.

                            #54207
                            filip_kbh
                            BRONZE Member
                              • Copenhagen
                              • Topics Started 13
                              • Total Posts 149

                              Can someone please upload a clear, zoomed in picture of the cpu board front and back? The service manual scan is not very clear.

                              #54204
                              filip_kbh
                              BRONZE Member
                                • Copenhagen
                                • Topics Started 13
                                • Total Posts 149

                                After changing the three diodes on the standby board plus fixing the trace on the processor board, the tape motor now spins but that is all. I still don’t know why I have 24V on pin 7 when it should be 7.8V. My measurements in red below. I am also missing a 15V supply.

                                Skærmbillede 2024-04-12 kl. 13.55.23

                                #54208
                                filip_kbh
                                BRONZE Member
                                  • Copenhagen
                                  • Topics Started 13
                                  • Total Posts 149

                                  Hmm – these three legs are shorted. Am I right in assuming that they shouldn’t be? It’s pcb3. When the board is not connected, the BeoCenter starts up with two relays and the tape motor kicks in. The chip is right under the battery damage on the other side, so who knows what’s underneath of great surprises.

                                   

                                  Skærmbillede 2024-04-14 kl. 22.46.05

                                  #54209
                                  filip_kbh
                                  BRONZE Member
                                    • Copenhagen
                                    • Topics Started 13
                                    • Total Posts 149

                                    Turns out the three pins get the same signal but there was a broken trace under the IC.

                                    #54210
                                    Ninni
                                    BRONZE Member
                                      • Topics Started 3
                                      • Total Posts 23

                                      The 7400 is a quad NAND gate. Connecting three pins together isn’t uncommon. You do it when you use one gate as an inverter.

                                      #54211
                                      filip_kbh
                                      BRONZE Member
                                        • Copenhagen
                                        • Topics Started 13
                                        • Total Posts 149

                                        Yes – thank you.

                                        I have now turned my attention to board 10. Since I am getting 24V on P74-1 (and it should be much less – 7.8V unregulated), I am looking at TR36, and it is not working properly, so I will have to replace that.

                                        However, it puzzles me that there is seemingly a short on the board. TR31  measured a short, so I took it off but even without the component, I still measure a short 🙁

                                         

                                        Skærmbillede 2024-04-16 kl. 21.41.52

                                        #55422
                                        filip_kbh
                                        BRONZE Member
                                          • Copenhagen
                                          • Topics Started 13
                                          • Total Posts 149

                                          I changed Tr31 and Tr36 but the unit is still dead. A relay clicks and the tape motor runs but that’s it.

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