Home Forums Product Discussion & Questions BeoGram Beogram4000 start issues

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  • #47102
    alf
    SILVER Member

      Hi All,

      I am over my Beogram 4000 now for a considerable time and can not find the problem.

      what happens here:

      activate ON, the platter starts at 45 !!

      The carriage does not automatically move in to the drop-down point, however I can manually switch to 33 and move the carriage forward, activate arm lowering and it plays as normal.

      i have been through the training manual and fault-finding flowchart in the SM.

      the SI circuit had a wrong BC183B fitted which is wrong – why and how that got in….no idea.

      i felt unsure about the correct replacement: BC184 or BC149 ? i chose the BC184 typ and it was working fine.

      now its back to the previous issue described ?? i have checked as per flowchart but obviously missed something fishy in there……but what ?

      can someone provide any other pointers than the fault-finding chart suggests ?

      as always, thanks for your help

      ALF

       

      #47103
      alf
      SILVER Member

        Hi,

        i revisited the adjustment of the platter motor as the table seem to have 45rpm locked in ?

        yes, I can operate a speed change manually, but….

        adjusting the motor as per SM I set all trimmers – 4VR1/2, 1VR1/2/3 – in their center position.

        I can adjust the corresponding  33rpm voltage at about 15V at 42Hz, 45rpm at about

        15V at 53Hz – not 59Hz as the training manual suggests.

        checking the SI signal I should see 6V after a 10ms delay…..what I am getting though

        is just under 2V which is obviously far too low……but why ????

        6V are present at the suppy, 1TR20 measures fine 1C15 is 10uF / 16V – no 6V cap at hand.

        the 24V supply is on the low side at about 23.4V ?!

        would really appreciate some input

        thanks guys

        ALf

         

        #47104
        filip_kbh
        BRONZE Member
          • Copenhagen

          If I read the schematics correctly, the fault could be between 1TR2 and 1TR3. So start by testing those two transistors.

          #47105
          alf
          SILVER Member

            Thank you for your input, I will test those two transistors.

            just a brief recap:

            i verified 6V at The C of  1TR20, but when measuring the SI on the mainboard the max I see is 2V ?

            i assume this is the signal 3IC4 is receiving ?
            it seems the logic has locked-in the 45rpm as the platter starts only with 45 when ON is activated.

            the components of the SI circuit are working ! The. Platter motor adjustment is another matter but should not interfere with the start-up of the carriage, moving in !

            i hope my explanation didn’t lead to misunderstandings here.

            any help is most welcome ?

            ALF

            #47106
            alf
            SILVER Member

              Tested the mentioned transistors – off board ! – and both tested fine.

              obviously one other (or more) component(s) is faulty as this issue was not a gradual decline but appeared suddenly.

              at this stage I want to rule out a contact issue as the table performs normal once the carriage has moved in via FE to its drop-down point.

              ALF

               

              #47107
              spassmaker
              GOLD Member

                Hi Alf

                Do I understand right? You are measuring 6 V at C of 1TR 20 and 2 Volt at SI on the mainboard?

                If so it seems that you have a broken trace between these points.

                SI is connected to several IC’s on the logic board under the button plate.

                Have already had broken wireconnections b etween mainboard and logicboard, maybe you have a closer look there.

                Kind regards

                Christian

                #47108
                alf
                SILVER Member

                  Hello Christian,

                  thank you for your reply – very sorry to say you just missed out on a 10/10,

                  But a  9/10 for inspiration isn’t too bad either I thought ?!

                  I did check that 1cm track under the magnifier, than clean that short track with a fiber glass pen as well and still did not see any damage…..which sidetracked me.

                  assuming that there may be a wire issue further on stopped me for now but thanks to

                  you I simply connected a short wire jumper between SI and C of 1TR20…..success ??

                  and now the platter starts at 33rpm as it should.

                  many thanks again ?

                  ALF

                   

                   

                  #47109
                  spassmaker
                  GOLD Member

                    Congrats, issue solved

                     

                     

                    #47110
                    filip_kbh
                    BRONZE Member
                      • Copenhagen

                      Nice!

                      #47111
                      alf
                      SILVER Member

                        Thanks Filip,

                        my thoughts precisely – nice to see the carriage moving correctly again.

                        always interesting how many challenges this table can throw at you……

                        ALF

                        #47112
                        sonavor
                        BRONZE Member

                          While we definitely come across plenty of failed, original components (due to age and whatever ordeals they have suffered), the number one cause of faults is still a broken connection.  Either a bad solder joint, a broken trace/pad or a faulty connector pin.

                          Those are often pretty difficult to find…so nice work in solving the problem.

                          -sonavor

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