Saba - Freudenstat 12

      Hi everybody!!

      I am new on this interesting forum and firt of all I wish you a Happy New Year 2013!!

      I am trying to restore my Saba - Freudenstat 12 and I would like your help with this following problem:

      Before the first IF filter the AM signal is strong and clear, getting many radio stations very well ( I am using a signal tracer). In the following diagram I point with the arrow in the pin 6 of the IF filter.

      But outside de IF Filter, It only gets a noisy (buzz) signal (no radio stations). Pointed with red arrow on pin 13.

      I changed the ECH81 and EBF89 for new tubes.
      Voltages are good.
      C34 is new one.
      Switches U3 and U4 are fine.
      I checked continuity for the coils L81, L82, L83 and L85. They are correct.
      The reading form Pin 13 to Pin 9 is 180 Kohm (the R81 value).

      I am thinking the IF is missaligned. Would be possible any capacitor inside the IF filter is out of value? I mean C81, C82, C83 or C84.

      Before put my hands on the calibration, I would like to know your opinion. Is it a common failure?



      Thank you very much in advanced !! :)

      José
      CHILE

      Hello José,

      thanks for your wishes.

      I asked a friend about your problem, he has the following remarks:

      You said, FM reception is ok, that means you are right, the problem must be in Filter II.
      You should have an eye on coils L85, L84 and L86 and their connections. Inside the filter you have to take care especially concerning breaks (open circuit).

      Check C84, C33 and the contacts of U3, I know you said they are ok, but also check the cables going there, as well as the switch for the bandwidth. Especially whatch out for shorts to ground.

      When using a signal tracer take care, that you should couple this with a small capacity (~10pF), not to detune too much the LC resonator.

      Finally, also a detuning of the secondary oscillating circuit (L85) could be the reason, but this happen not without being touched by „foreign“ intervention, so only by unthought turning of the tuning kernel.

      Question; What do you mean with :
      "But outside de IF Filter, It only gets a noisy (buzz) signal (no radio stations)."
      Can you give some more hints, is it just noisy or does it have your net frequency of 50 Hz?

      Anyway I hope we can help you.
      Please keep us informed.

      Best
      Vorex

      Hello Vorex:

      I am sorry for the delayed answer.

      You were right. Following your instructions I opened the Filter II and inmediately comes up the FM signal and clear sound on the speakers. Reviewing the inside contacts there was a thin wire from a coil touching the metal can. I putted a thin plastic film in between to isolate the connections.

      I will follow your hint using the 10 pF capacitor with my signal tracer.

      Thank you very very much indeed for your help. I am very happy with my old SABA working great !!!!

      All the best,

      José from Chile