Saba 9140: Mittenanzeige schlägt nach rechts aus

      Saba 9140: Mittenanzeige schlägt nach rechts aus

      Moin,

      der 9140 hat vor einigen Jahren die üblichen Wartungsarbeiten erhalten und spielte seitdem problemlos. Gestern verlor er plötzlich den Sender und die Mittenanzeige schlägt nach rechts aus. Bei Änderung der Frequenz ändert sich die Mittenanzeige in der Größenordnung von etwa 1 bis 2 Teilstrichen auf der Skala, also wirklich sehr gering. Auch ohne angeschlossene Antenne ist der Rechtsausschlag vorhanden. Die Aussteuerungsanzeige ist dagegen unauffällig. Ich meine, den Sender hat er aus dem AFC verloren, weil sich das Frequenzband minimal verschoben hat. Ich meine, die Sender liegen nun etwa 1 MHz höher auf der Skala.

      Wo sollte ich den Fehler suchen?

      Das Foto wurde ohne angeschlossene Antenne aufgenommen.




      Danke und Gruß
      Michael

      Dieser Beitrag wurde bereits 1 mal editiert, zuletzt von „Shibamata“ ()

      Hallo Michael,

      wo suchen?
      IM ZF-Verstärker-Kästchen!

      was kann es sein?
      Eines der beiden Trimmpotis (oder beide) sind evtl. vergammelt, eines hat ggf. den Schleiferkontakt verloren.
      Es kommen auch noch andere Dinge als mögliche Ursache infrage. Aber erfahrungsgemäss sind Trimmpoti-Ausfälle bei einigen Serien eine Pest.

      Gruß
      Reinhard

      Hallo Reinhard,

      ich traue mich kaum es zu schreiben: Volltreffer. Auf die Schnelle habe ich beide Potis ganz wenig hin- und hergedreht, wieder eingebaut, eingeschaltet: Passt! Ein wenig aussermittig, das justiere ich demnächst noch mal sorgfältig. Dazu muss ich mir erst mal einen Schraubendreher isolieren, um im einschalteten Zustand keinen Schaden anzurichten.

      Danke! :thumbsup:

      Gruß,
      Michael

      Es empfiehlt sich, einen Abgleich-Schraubendreher anzuschaffen. Die sind aus Kunststoff, und haben nur vorne eine kleine Klinge (die gibt es auch in Keramik, braucht man aber für die Potis nicht). Kleine Sets gibt es z.B. beim grossen R, aber auch sonst im Handel. Braucht man eigentlich oft genug, dass es sich lohnt.

      Besten Gruss,

      Michael

      Hello,
      saba 9140, ask for advice on a usage problem:
      The 8 buttons in the lower right corner, FM-1-2-3-4-5-6-7, 1-7 are storage stations,
      The text below the FM button is, sus afc ein, what does this mean? I do not understand,
      At present, I cannot manually tune after pressing the fm button. Is there something wrong with me?

      On my 9140, the 7 storage buttons are normal. Press the fm button, manual tuning does not work, and the pointer can move.

      Dieser Beitrag wurde bereits 4 mal editiert, zuletzt von „wyx12007cba“ ()

      You wrote:
      "The text below the fm button is "sus afc ein", what does this mean?"

      It is actually written below the afc control button: "aus afc ein", which in English means "off-afc-on".
      afc stands for "automatic frequency control. If switched on (to the right=ein), it holds the frequency tuned to the reception frequency stable and captures the correct transmitter center frequency at its correct center value, if slightly de-tuned.
      Thus, turning the afc knob to the left (aus=off) switches afc off, turning it to the right (ein=on) switches afc on.

      It is explained in detail in the user manual of the SABA 9141tc (which applies for this function also to the SABA 9140):




      You should be able to manually tune a fm station with the tuning wheel if the fm button is pressed (only the fm LED above the fm button shall light after pressing the fm button,but none of the pre-set fm- storage indicator LEDs must light after pressing the fm button). Otherwise you have a malfunction.

      If you can receive fm normally when you press one of the pre-set fm storage buttons (and the respective LED belonging to the pressed fm storage button lights also), but after pushing the "fm"-button the fm indicator led does not light and you cannot tune a frequency with the tuning wheel, you need to check:

      transistors T1041,T1042 and T1086
      AND
      especially, if you can detect the required +23V DC at the emitter of T1042, (voltage no. "+12" to the indicator module).
      It is possible that the voltage no. "+12" is missing, i.e. because the cable or contact/plug from the indicator module is defective/broken.

      Further to check:
      a) Is Voltage at Measurement Point B8 correct (+31V)?
      b) Is voltage at Measurement Point B9 correct (+4 V)?
      c) Is voltage at Measurement Point A1 correct (+29,5V)?

      Regards
      Reinhard

      Dieser Beitrag wurde bereits 4 mal editiert, zuletzt von „oldiefan“ ()

      Hello,
      Thank you very much for the teacher's explanation. I turned on the machine and first checked the tuning cable part, and found that the screws on the cable reel were loose, causing manual tuning to fail.
      Second, I followed your steps again, checked the tuning circuit and replaced a triode.
      The state of the machine is normal now, thank you very much, teacher.
      I love this saba forum.

      Hello, teacher oldiefan,
      I'm here again, again with a question.
      I just bought a SABA 9140, and it can sound normally when turned on.
      Fault:
      1. The memory (19) defaults to U1 after booting. I think the default should be U (manual) when booting. Is this a fault?
      2. U/U1/U3/U5/U6 are in normal use, but U2/U4/U7 are not normal. Pressing down will not work.
      3. I tried to replace two ICs and the fault still exists, (IS1086 and IS1081), indicating that this is not the cause of the fault.
      Ask the teacher for the solution, thank you.



      wyx12007cba schrieb:

      1. The memory (19) defaults to U1 after booting. I think the default should be U (manual) when booting. Is this a fault?


      I believe that Michael knows that better than me and shall correct me if I am wrong.
      The user manual states that upon powering up, the 9141 switches to FM (U) by default. If it switches to U1 instead, it is a fault, yes.
      Check/or replace transistor T1086


      U/U1/U3/U5/U6 are in normal use, but U2/U4/U7 are not normal. Pressing down will not work.


      Wires connecting the switching board and/or the station pre-set board and/or the station pre-select unit might be broken or interconnects between these units make bad contact.

      Best Regards,
      Reinhard

      For your first "fault", coresponding to the servicemanual, the units switches on with U1, due to C1182.
      If you want to change, resolder C1182 to the function you wish in the same way.

      The second one, I think the switches aren´t working proberly. You can check this by shortening them on the backside of the PCB with a pair of tweezers or similar.

      Greetings
      Peter
      Auch ich kann mich irren......

      Dear friends,

      After several days of careful research, the problem of the saba 9140 was finally solved,

      I have explained the fault in the previous posts, and now introduce the maintenance process:

      Fault phenomenon:

      1/The power on is normal, and manual tuning can be performed. Only 2 of the 7 FM storage tables display normally, and the other 5 fail and do not work.

      2/Fault finding:

      Check the triode and integrated chip on three boards 17-18-19. After replacing the triode T1086/BC239A, the fault still exists;

      IC IS1086/IS1081/IS1071 are replaced, and the fault still exists;

      Check the voltage of three boards. It is found that the T1042/BC238B power supply is low, and the measured voltage is 17v (called 23v in the circuit diagram); Measure the B8 terminal, and the measured voltage is 26v (called 31v in the line diagram);

      3/Solution: Adjust P516 variable resistor, adjust the voltage to 31v, and all the 8 FM storage functions will return to normal after startup. The fault has been solved.

      After the introduction of my inspection and maintenance, please correct me.







      Dieser Beitrag wurde bereits 2 mal editiert, zuletzt von „wyx12007cba“ ()

      I see something on the TCA 530 board that is strange: The two blue capacitors next to the TCA 530 should be tantal caps, or film, but not standard electrolytics.

      What is wrong with the BAP 812 ? Seems to be a 12 V stabilisation diode, but I need to check the full circuit before suggesting a replacement. Probably some 12 V zener could do ...

      Michael

      p.s.: This is not from the 9140 --- what radio or receiver is it ?

      p.p.s.: Stabilisation is correct, the 12 V are not. See below for details.

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