saba: Saba Freiburg 100 automatic tuning motor problem

When I first switched on this radio the tuning motor did not work. I checked the resistance of the 4 coil windings and one was faulty, only measuring 100ohm while the other 3 were close to 1k. After rewinding the faulty coil the resistance was also close to 1k.

With the power off the repaired motor turns freely by hand but once I turn on the power the motor sounds like it's trying to turn but is tight in both directions with no movement. The capacitors in the motor circuit have all been changed. 

I am hoping someone has experience with these tuning motors and can help me find the fault.

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I'm making progress after a private message from another member to check the values of the capacitors. One capacitor that should be 0.4uF was measuring 0.46 and after replacement the motor turns correctly in both directions, however very weakly and will not move the dial chord.

could this be due to a weak ECL80 valve?

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Dear Kevin,

there are some critical issues with the tuning motor. Some of them you already checked

1) The motor has to be clean and oiled carefully and should move easily as you already did

2) The coils have to be tested. They should measure around 1 k. That is what you already did.

3) Test if the coils may have a short circuit to ground. The insulation of the coils may be faulty

4) Measure condensators C64 (0.4 µF) and C67 (0.35 µF). The values should be as near to the required values as possible.

5) Check the emission of the Rö 6 (ECL 80) valve.

6) Check emission of Rö. 5 (EABC 80) and required values at the electrodes.

7) Make sure that alle currents and voltages at the electrodes of the Rö. 6 (ECL 80) valve are according to the circuit diagramm

8) Check if the dial chord moves easily. Clean and carefully oil the bearings of the chord and the tuning condensator if neccessary.

9) Check the contacts of the "Steuerschalter". Clean the contacts if neccessary 

10) Check the relay L_D Rel. 3 if it moves freely

Hopefully after this checklist the motors moves as required. Good luck.

Best regrads

Rüdiger 

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Dear Rudiger, thanks for your checklist, I will work through it today. Prior to my first post I did check for shorts in the coils. One of the yellow wires from a coil had damaged insulation and was shorting against the mounting screw.

As for the capacitors, the 0.4uF was too high and replacing that resulted in slow movement of the motor. The original 0.35uF is in a large metal can and it failed a leakage test so I replaced it with a film capacitor 0.33uF 630vdc. This is the AC connection to the motor so hope that capacitor is suitable.

I have a new ECL80 valve somewhere, I will try swapping it out with the old valve which is slightly weak.

Regards Kevin

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Hello Rudiger,

I have changed the valves you mentioned as they were weak and there is a slight improvement but the motor barely turns the tuner. I will clean and lubricate all the tuning parts as you mentioned.

The capacitors are correct value and the voltages are within 10%.
Just one question, you mentioned Relay 3, i cannot see how this can move as there is simply a metal Rod through the middle that is bolted to the frame. Could you explain it's purpose and workings.

Regards

Kevin

 

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