saba: 12-Stereo; Freudenstadt

Hi everybody:

I need yor help in order to restore my Saba Freudenstat 12.

I has the power transformer burned (the primary wound).

I must to send it to rebuild and I am trying to calculate the parameters. I will really appreciate your information and/or checkup of my calculations.

The radio has the following tubes with this data (taken from RMorg):

Then for the high voltage of the power transformer (secondary), I will need:

a) Total Current for Anodes Current:  104,41 mA   (adding all the anode currents from the table)

b) Voltage: 235 VAC (showed in the schematic).

For the heathers I will need another secondary with:

c) Voltage: 6,3 VAC

d) Total Heather Current: 2,685 A (adding all the heather currents from the table)

Is this correct?. If yes, What woud be the tolerance for the voltages and the currents? What are the values that I need to add to the calculated values, in order to assure the new transformer will run very well.

By the way, I will use the same nucleus to rebuild the transformer.

Thank you very much in advanced.

José

 

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I would assume about 15% to  20% tolerance, but allow more on HT as the Screen Grids (g2) also take current.

So 6.3 & 3A is a little tight on LT, 3.5A better, maybe 20VA is OK. On HT 125mA to 130mA is maybe far too tight, I'd allow 150mA or more to allow for ripple current and peaks, so maybe 35VA to 40VA, total transformer rating about 55VA/55W minimum.

 

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Hi Michael:

Thank you for your soon and useful answer. I took your tips and I sent to rebuild the transformer yesterday. I will tell you the advances.

All the best and Happy New Year 2013!!!

 

José from Chile

 

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Hi everybody:

Continuing with the restoration of my Saba - Freudenstat 12, after install a new transformer (all the voltages are good now), it presents the new 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

please keep size within 600px and upload picture better to RM-server, it might disapear otherwise one day, thanks

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Hello everybody:

Following the excellent advices from  Vorex, a friendly german radio collector, 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 am very happy with my old SABA working great !!!!  Thank you very much Vorex.

Best regards,

José

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