Saba 9241 fm-rnitte Indicate questions

      Saba 9241 fm-rnitte Indicate questions

      Hello everyone!
      I'm here to bother you again. When my machine is turned off, the FM meter indicates normal. After turning on the machine, I tune it. The pointer only swings in the red triangle area and does not swing to the left. It seems that the indicated frequency is not very accurate. Please give me some advice. Some suggestions for repairs, thank you very much!

      oldiefan schrieb:

      Hello again!

      Adjustment:

      Tune to a transmitter precisely, so that the field strength indicator meter (Abstimmung) is exactly at its maximum. Then adjust potentiometer P2022 so that the fm-mitte indicator pointer is in the center.

      saba-forum.dl2jas.com/index.ph…316365488503a1b6cae6e92a5



      Best Regards
      Reinhard



      Hello old friend!
      Thanks Reply! After adjusting according to the method you mentioned, rotate P2022 to the right to the position where it cannot move. When the pointer moves to the 1 position on the right, it will no longer move toward the center. When the pointer is at the center position, the frequency will deviate. What is the problem?

      It looks that there is some readjustment required in the fm-if box.

      1) Remove the two screws (at the rf-main board solder side) holding the fm-if box (FM-ZF-Modul). Then, pull out the fm-if-box and plug it onto the back side of the rf-main board onto the corresponding pin row. Watch out that you put it in the right direction (same direction as on the parts-side), that is pin 1 of the box must match pin 1 of the pins on the board.

      2) Attach a DC-voltmeter between measurement points B5 and B7 at the rear side of the rf-main board. Measurement range 200 mV DC.
      3) Then tune exactly to the frequency of a medium to strong transmitter, so that the fm signal strength indicator meter (Abstimmung) is exactly at its maximum.
      4) Adjust the reading of the DC-voltmeter (between B5 and B7) to 0.00 V (+/- 10 mV) with potentiometer P324 inside the fm-if box. watch out that you do not touch the metal shield of the fm-if box and P324 at the same time (that would cause a short), if necessary wrap the screw driver with isolation tape before. Do not move the tuning while doing this (tuning shall stay at max. signal strength).

      - Now you got electrically zero Volts at the center meter (fm-mitte) when you have tuned exactly to the transmitter frequency-

      5) With the DC-voltmeter displaying zero Volts between B5 and B7 (as adjusted in 4) adjust now potentiometer P2022 (the potentiometer, you know already) for center indication of the pointer of the center indicator meter (fm-mitte).

      If it is still not possible to adjust for center on the fm-mitte instrument, the center indication meter mechanism may be mechanically defective (I hope not).
      If it is not possible to obtain zero Volts between B5 and B7 at max field strength indication (Abstimmung), the fm-if is probably heavily misaligned. That would require a more tedious procedure.


      Best Regards,
      Reinhard

      Dieser Beitrag wurde bereits 6 mal editiert, zuletzt von „oldiefan“ ()

      oldiefan schrieb:

      It looks that there is some readjustment required in the fm-if box.

      1) Remove the two screws (at the rf-main board solder side) holding the fm-if box (FM-ZF-Modul). Then, pull out the fm-if-box and plug it onto the back side of the rf-main board onto the corresponding pin row. Watch out that you put it in the right direction (same direction as on the parts-side), that is pin 1 of the box must match pin 1 of the pins on the board.

      2) Attach a DC-voltmeter between measurement points B5 and B7 at the rear side of the rf-main board. Measurement range 200 mV DC.
      3) Then tune exactly to the frequency of a medium to strong transmitter, so that the fm signal strength indicator meter (Abstimmung) is exactly at its maximum.
      4) Adjust the reading of the DC-voltmeter (between B5 and B7) to 0.00 V (+/- 10 mV) with potentiometer P324 inside the fm-if box. watch out that you do not touch the metal shield of the fm-if box and P324 at the same time (that would cause a short), if necessary wrap the screw driver with isolation tape before. Do not move the tuning while doing this (tuning shall stay at max. signal strength).

      - Now you got electrically zero Volts at the center meter (fm-mitte) when you have tuned exactly to the transmitter frequency-

      5) With the DC-voltmeter displaying zero Volts between B5 and B7 (as adjusted in 4) adjust now potentiometer P2022 (the potentiometer, you know already) for center indication of the pointer of the center indicator meter (fm-mitte).

      If it is still not possible to adjust for center on the fm-mitte instrument, the center indication meter mechanism may be mechanically defective (I hope not).
      If it is not possible to obtain zero Volts between B5 and B7 at max field strength indication (Abstimmung), the fm-if is probably heavily misaligned. That would require a more tedious procedure.


      Best Regards,
      Reinhard


      Hello old friend!
      Thank you very much for your repair solution. The machine is now fully working normally.
      Welcome to China as a guest!
      Best greetings from China!