Hello from Cuba

[Nowhere-Man]

About 2.30 am and I just spent some time working on the Astrad. I am pleased to say it is now working, although no stations at all picked up. Just background hissing and sounds like it tries to receive if I jolt the waveband knob. Even so, I am content with some progress. I felt I needed to get access to the power supply so had to remove knobs and lots of rusted grub screws. The set was awkward to manipulte out for insoection and one knob had been glued. Finally the lamps turned out to be kaput but it was easy to trace the power circuit. Now I know audio output is fine I might as well develop the projectt and strive to get stations. I can also renew any suspect caps and clean the waveband mech

[Miguel Lopez]

In Miguel's case (Cuba), radios were supplied in the early sixties so I guess they are plentiful in Cuba.

I wasn't aware that you were talking about Soviet radios here, sorry. Have to say that I have never seen an Astrad in Cuba. We have plenty of VEF-202, 204, 206, 221 and 260; Selena B210, B211, B212, B215 and B216, Sokol, Meridian, some VEF Spidola, and then the Cuban copies:

Siboney (Spidola 230)
Ritmo (VEF-221)
Taíno-74 (Orbita-2)
Juvenil-80 (Radiotehnika-625)
Nocturno (Abava 8330)
Pionero (Selga XXX?)

But as I said, I have never seen an Astrad. This doesn't mean that there isn't.

Miguel, as we know, is a specialist in Soviet radio tech repair so he will know all the irregularities of the design

Not really, I'm just a hobbyist.

I always work on the following direction: A radio has two sections: audio and RF. Connect the oscilloscope at the audio output of the RF section and move the dial. If there is an audio signal there, then it is the audio amplifier, if not, it is the RF section; then focus your effort on the faulty section.

Other way, remove the speaker and connect a similar resistance resistor there and connect the oscilloscope across this resistor; then apply a 1kHz signal to the input of the audio amplifier, and see if that signal appears at the forementioned resistor. That will tell you if the audio amplifier is faulty and focus your effort there.

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PS: @MODS, please replace the "n" by an "m" in the title of this thread. I really feel ashamed for that typing mistake

[Mark Hennessy]

PS: @MODS, please replace the "n" by an "m" in the title of this thread. I really feel ashamed for that typing mistake

Done

[Miguel Lopez]

I think the closest to the Auriga I can get in a short few minutes is below. Can't guarantee it exactly corresponds but with a bit of practice I ought to be bale to dig up a few old Soviet manuals.

Be sure that all MP41 and the MP37 transistors have their legs intact. They usually break due ro rust. P213s can also have broken legs, but that is less usual cause those are thicker.

Does that set has red-squared capacitors? If that is the case, try to replace them all.

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@ Mark : Thanks

[Miguel Lopez]

Maybe I have discovered the warm water, but I have found (by comparison) that the Astrad Auriga is a VEF-12 with another name. Am I right?, and so both are very similar to the old good and venerable VEF-206.

[Nowhere-Man]

Hi Miguel, Espero que estes bien. Muchos saludos. I am very pushed for time at the moment so will tell you more details about the Astrad later. I will need your advice on a few points. The audio is working fine now but I discovered the middle ferrite aerial coil is disconnected. That is one obvious problem. I will need to resolder the winding. I am not yet sure where the original connections were but will investigate. The power capacitors are a sort of grey colour and the transistors "top hat" type. These radios were built in Riga where I have lived. Mine has 1969 on the speaker so would have been exported as the Astrad in the Brezhnev era.
I am also working on an East German GDR valve radio 1964 you would find interesting as it's a mix of German engineering and maybe a bit Soviet too. This has valves ECH81, EBF89, EABC80 and ECC85. This latter is printed circuit mounted and I am studying the schematic before I do any involved work on it.

[Nowhere-Man]

I am led to believe the Astrad Auriga or Astrad Solar was called the Riga 103 which is a USSR model. The one you showed Miguel, must also be the same I imagine. I should point out I am very inexperienced with transistors as also with FM. However I would like to do some transistor radio repair and may try to do some Soviet radios as I find that especially interesting. If it is OK I will ask you for some tips and if you need Soviet schematics I can probably locate them on yandex.ru for free. Please excuse the fact I type this on an old dated Blackberry and it is hard to see the screen

[Miguel Lopez]

I am led to believe the Astrad Auriga or Astrad Solar was called the Riga 103 which is a USSR model. The one you showed Miguel, must also be the same I imagine.

Astrad Solar is diferent from the one I showed. I found it at RMorg. But have to say that in the googling that I did to know the Astrad, the Solar appeared with the AURIGA marking too, so have to say that I'm confused. I do sustain that I have never seen any Astrad here in Cuba.

If it is OK I will ask you for some tips

I will be very happy to help as everybody has helped me in this community. I can share my experiences on Soviet radios repairing.

I discovered the middle ferrite aerial coil is disconnected.

If yours is the one I posted, that will be very easy. The layout in the schematic is very explanatory.

The power capacitors are a sort of grey colour

Don't worry about that. By the time they were building the VEF-206 family, they did not used the red-squared capacitors yet. Your set uses paper capacitors rated at 160V which never fail. In fact, the VEF-206 uses just one red-squared capacitor which is the cause of fault very often. You just remove it from the PCB and the set works fine.

the transistors "top hat" type

As said before, the problem with those transistors is broken legs due to rust. They are good transistor electronicallywise, but the legs break time after time. The RF transistors can be replaced by 1T308, and the AF transistors can be replaced by any general purpose silicon one, if you correct the bias point. The diode of the constant current source can be replaced by a 1N4148, althought I have never see this diode fail.

Sometimes you want to throw your Soviet radio through the window because of erratic behaviour, but being patient you learn to like them and restore them. Enjoy the trip to the Soviet-era-radio-land.

[Nowhere-Man]

Thanks, Miguel. I will definitely follow your advice and hope you stay on the forum to share your experience with these USSR radios. So far I have had some success with this Riga radio.. It was initially totally dead. The battery compartment was doing nothing. I finally decided to dismantle the chassis so all the knobs had to be removed. The waveband knob was hard because the grub screw was accessed down the shat. I had to push the aerial right down as well to clear space to wriggle the chassis free. I then found the bulbs were dead. After tracing the power lines it finally burst into life but no stations yet.

[Nowhere-Man]

Now I found the workshop voltages, the mystery of my Soviet GDR valve set is hopefully being solved. The ECH1 Triode Heptode has no voltage on the oscillator anode. What had also confused me is there's a ECC5 double triode that is oscillating OK for FM. Given the schematic is in German that didn't dawn on me at first. So I am missing my mixer for AM and other bands. I am now planning to do some Ohms tests to see if HT is getting to the oscillator anode. This may be a bit trici could also just try a substitute mixer as possibly the ECH81 is defective. Meantime I had to learn a few German terms to better understand the schematic.