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Old 17th Oct 2014, 5:14 pm   #21
MajorWest
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Default Re: Restoring my old Soviet radios

Quote:
Originally Posted by Miguel Lopez View Post
We were humble but very happy during the 80s. Nostalgia from good times.
Now, as Paul says, let's keep focus on restoring radios.
Que tal, Miguel!, Sure, I think your specialisation in these radios is really cool. I was just looking at a Radio Zvezda set from the fifties. Maybe at some point I'll see if I can get some Soviet radios to mess about with but don't think I have the experience yet.
Have you ever found any USSR radios that use metal rectifiers or are they always valves? I'm led to believe that metal rectifiers were used a lot in European sets so not sure about USSR. Do they all use transformers to supply HT and is it always full wave or half wave rectification?
Anyway, great to see you are becoming a bit of an expert in this field of engineering and best of luck with your radios.
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Old 17th Oct 2014, 5:30 pm   #22
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Default Re: Restoring my old Soviet radios

Miguel won't have much experience of Soviet valve/tube radios because the Cuban revolution only happened in 1959. Before that I guess most of the radio imports would have been American, perhaps with a few European luxury radios like Grundigs.

Miguel is discussing Soviet transistor radios of the 60s and 70s.
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Old 17th Oct 2014, 6:36 pm   #23
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Default Re: Restoring my old Soviet radios

As Paul says, I have never seen a Soviet valve radio. When Soviet radios began to be sold in Cuba, they were all transistor sets. The first widely sold was the VEF204 and 206. I have seen a few examples of VEF Spidola, but it wasn't widely spread here, and I think they were brought by Cubans who visited the USSR.

Quote:
Originally Posted by MajorWest
great to see you are becoming a bit of an expert in this field of engineering
Well, I'm not an expert, just an enthusiast hobbyist.

Quote:
Nice collection of Soviet radios!
I also have quite few of those, among them three Vef 204/206 radios.
VEF206 is my favorite. I think my little collection will increase as people knows about my hobby and some of them are eager to give their old Soviet stuff to any crazy guy who wants to adot them.

By the way, yesterday I powered some of my other radios and I think I can restore three more of them. The "Ritmo" (Cuban copy of VEF221) works but need some work at the PSU and the tunning capacitor pulley.

The Taíno74 needs replacement of the audio output transistors, and the Juvenil80 requires another ferrite bar, cause it is broken and one piece is missing. I have another Taíno74 for spares so the ferrite bar won't be a problem. It seems I can put back in service this three examples.

I will share with you my advances, but it will be slowly cause by these days I need to stop from time to time to do "meal electronics".
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Last edited by Miguel Lopez; 17th Oct 2014 at 6:41 pm.
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Old 23rd Oct 2014, 1:30 pm   #24
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Default Re: Restoring my old Soviet radios

Here some of the advances that I have doe on the Selena. I fixed the audio amplifier which had a faulty MP37 transistor. I have several brand new (NOS) MP37 so it kept the original types.

I also worked on the PSU which had the P213 transistor with a broken leg, so I replaced the entire regulator circuit by an LM317 adjusted to get 9V. The mains button is faulty so I re-wired it to use the red button (batteries) to power the set. I hope to work on the wooden piece on weekend if the cyclone allows me.

Here some pictures
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Old 27th Oct 2014, 2:20 pm   #25
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Default Re: Restoring my old Soviet radios

Well, the Selena is already working, electronically-wise. Now it is time for carpentry, which is the most difficult task for me (lack of skills and lack of suitable tooling). The wooden framework is not complete so I have to build a couple of parts to complete it. Soviet used wood to make the framework of the Selena, by some unknown reason, they should know :aaq . I think that plastic or bakelite would had been better, but they should know.

Carpentry is something that I don't do very well. I lack the suitable tooling for that so I do my best with what I have at hand. Here I show a picture with the only two parts that I have of the framework and the other two that I made to complete the framework.

Originally, it was glued, but I used bolts to fix it. Not so orthodox (or beautiful), but it works.

I have also posted a picture of the first two radios restored (or something ) during this adventure.
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Last edited by Miguel Lopez; 27th Oct 2014 at 2:25 pm.
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Old 27th Oct 2014, 5:43 pm   #26
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Default Re: Restoring my old Soviet radios

Quote:
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Carpentry is something that I don't do very well. I lack the suitable tooling for that so I do my best with what I have at hand. Here I show a picture with the only two parts that I have of the framework and the other two that I made to complete the framework.
I have to do carpentry as well sometimes and I found it can be difficult. Sometimes I have had to cut one curved line to match another curved line. I learned to use string and a pencil to trace edges on my wood and then use a jig saw to cut the curved line. Sometimes I've bent thick wood as well by leaving it in water for weeks and then bending it to shape.
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Old 27th Oct 2014, 7:27 pm   #27
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Default Re: Restoring my old Soviet radios

I have no idea upon the availability of wood glue in Cuba, if it is rare a very good glue can be made from milk, it is casein, used, I think, to glue Mosquito aircraft together in WW2.
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Old 27th Oct 2014, 8:11 pm   #28
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Default Re: Restoring my old Soviet radios

I'm deeply fascinated by your restorations: in the 1970s my elder brother bought a couple of Vega VEF210 radios which were at the time being imported to the UK [along with 'Zenit' cameras] by a company called "Technical & Optical Equipment" in the UK.

The VEF210 still used Germanium transistors - the one used by my parents needed occasional re-seating of the transistors into their sockets.

It also had lots of problems with tarnished contacts on the turret-tuner [vigorous forward-and-back action made it work] and the "TOE"-supplied Soviet-made mains power-supply was really rather questionable from an electrical-safety perspective.

Still, when it was on-song it was really rather loud!
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Old 27th Oct 2014, 9:01 pm   #29
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Default Re: Restoring my old Soviet radios

Quote:
Originally Posted by merlinmaxwell
if it is rare a very good glue can be made from milk
Nop, nop, nop....Milk is more scarse than wood glue (and more needed too)

Quote:
Originally Posted by G6Tanuki
[vigorous forward-and-back action made it work]
Yes, I know what you're talking about. It was the same for TV sets channel selector
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Old 3rd Nov 2014, 5:20 pm   #30
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Default Re: Restoring my old Soviet radios

A new challenge.

Well, an uncle of mine has a Siboney radio. This is a Cuban copy of the Soviet Spidola 231. It is the worst Soviet radio among those who were sold in Cuba during the Soviet period, but it works. Problem is that my uncle love to hear baseball on it. In Cuba, baseball is passion, and my uncle is very passionate. From time to time the old Siboney stops talking (due to bad contacts on the turret or pot slider), and my uncle, lacking patience, hit the radio to make it talk again (similar to a Gestapo agent).

Results: The radio is in very bad condition (simlar to a prisoner of Gestapo). I fix it from time to time, when the damage is very huge (mechanical damage mostly), but the last time I suggested him to find an old VEF 206 radio that a friend of him would have abandoned in a remote corner (there are a lot of VEF-206 on such status in Cuba, I can assure) in order to restore it and replace the Siboney. I have some experience with the VEF, but almost nothing on the Siboney (pendant homework). I also have some parts for the VEF but I'm not sure for the Siboney, which is more complex.

My uncle found a VEF very quickly, cause as I said, there are a lot of them in Cuba. The set is in bad condition too, but it is in one piece (except for the handle). The speaker has several holes, because Cuban cockroachs love the paper from Soviet speakers and they eat it, openning holes. The PCB had a potter wasp nest on it

I think I can restore this set to an acceptable working condition and then retire the battered Siboney.

Here some pictures of the VEF-206 set
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Old 3rd Nov 2014, 5:35 pm   #31
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Default Re: Restoring my old Soviet radios

Hopefully a pint of switch cleaner, some tissue paper and watered down PVA glue will get that working. Good luck with the cosmetics, though.......
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Old 6th Nov 2014, 2:53 pm   #32
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Hi

I need your advices with the VEF206.

The radio is already working but there are some details that I need to solve and I don't know how.

I connected the PCB to the other VEF206 (the one that was restored first). I was able to make this PCB to work, but the band is "moved" (not sure if this is the right word in English, sorry), I mean that some stations that are usually tuned near the right end of the dial, are now tuned near the center of the dial, and therefore, those stations which were tuned near the left end, are now "out of the park" and I can not tune them.
The tunning tanden capacitor runs from maximun to minimun on both ends of the dial.
How can I move the band to the correct ranges?

There is another "misterious" detail. When I connected back the PCB to its own set, the radio didn't work, so as I knew that the PCB was OK I searched for a problem on amother place. Everything seemed to be OK, and then I rhought to swap the MW sections on the turret of both radios. The results is that the MW section from my uncle's radio works fine on my own radio, with the stations on their usual place.

The MW section of my own radio works on my uncle's radio but with the band moved too. If I swap them again, my radio works fine but my uncle's doesn't. Can't explain that.

This leads me to think that the "band moving" is inherent to the PCB.

This sound like a puzzle, and I hope to have explained well in English. I will explain more if needed.

Any help welcomed.
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Old 6th Nov 2014, 3:44 pm   #33
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Default Re: Restoring my old Soviet radios

Hi Miguel,

When the bands move on the scale the local oscillator frequency is different. The components that are on the PCB and are part of the resonant circuit of the LO could cause this.
Looking at the schematics, C39 and C43, 1nF and 68pF respectively, has some effect on the LO resonant frequency.
See if those capacitors have the same values.
Different parameters of the oscillator transistor T1, like the collector capacitance (Cc), could also cause shifting of the oscillator frequency.

Peter

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Old 6th Nov 2014, 9:45 pm   #34
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Default Re: Restoring my old Soviet radios

Hi Peter

Thanks for your answer.

I was studying the schematic. Is C33 the padder cap on MW for the LO?

I will replace the LO transistor by an 1T308 to see what happen.
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Old 7th Nov 2014, 12:26 am   #35
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Default Re: Restoring my old Soviet radios

Hi Miguel,

Yes, C33 is the padding capacitor for the MW LO. That one is on the turret.
I understand that those radios are notorious for having bad contacts with the turret.
Knowing the accuracy of the mechanical things there, do you have contact with all the pins on the coil assembly? Swapping them could account for misalignment and not adequate contact.

Peter
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Old 7th Nov 2014, 1:43 am   #36
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Default Re: Restoring my old Soviet radios

Peter, all Soviet radios with a turret wavechange arrangement tend to develop bad contacts with age, and it's very important to clean the contacts carefully, but I suspect Miguel is aware of that.

It's possible that the MW padder capacitor has failed open circuit, which would explain the frequency displacement.

The environmental conditions in Cuba are obviously very different to those in western Europe (and Canada ), so components will degrade in different ways and our experience here may not transfer well to Miguel's circumstances.

I would not expect a transistor fault to cause a change in the local oscillator frequency.
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Old 7th Nov 2014, 3:35 pm   #37
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Default Re: Restoring my old Soviet radios

Hello Miguel, I am interested to know you have started on Soviet Radios as I have a few in my collection. I think you will find it very rewarding, when working properly the performance is very impressive. Many were imported into the UK by TOE as has been said earlier. At the time the cost was quite modest and I doubt whether there was any other multi band radio available that compared in performance or price. I understand that TOE had a team of technicians who checked them in the UK before sale to ensure they had not suffered in transit.

Your MW problem is puzzling because the coil strip that also includes the trimming capacitors seems to be fine, when you put it in another working set it was OK. A known good coil strip put in the set you are repairing gave the same problem. I can't think there is anything on the pcb that is only used on MW. You might find there is some distortion in the turret switch that prevents proper contact with one of the spring fingers and the studs but only in the MW position.

As Paul has said, it is interesting to think that faults might be very different because of climate. The rusting leads of the transistors is a point I had not thought about. I have only had one instance of this and I changed the transistor for a similar general purpose type and this solved the problem. The only major mechanical problem I have found is that the plastic tends to get brittle and can easily break. It emphasises that these are old sets and when they were built there may not have been much information on the life of the plastics used for the moulded parts.
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Old 12th Nov 2014, 3:40 pm   #38
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Default Re: Restoring my old Soviet radios

Hello again.

The radio is working fine except that I have no speaker for it. I try to fix the original in the usual way that I do, glueing paper on the holes using PVA. Well, the speaker sounds awful, so I have to replace it. I tested it with the speaker from my mother's Selena and the sound is clean and nice. I think that the speaker from my uncle's Siboney won't fit the space cause it is bigger.

A friend of mine gave me one PC speaker, but it plays almost no bass, just trebles, so it sounds like a cricket. I will try to find another speaker for the radio. Here some pictures.

The radio also lacks the handle, but I will try to find another "dead" set to donate its handle.
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Old 12th Nov 2014, 4:10 pm   #39
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Default Re: Restoring my old Soviet radios

I forgot to tell you. Sensitivity was poor. The strong stations were tunned OK but some other with weak signal were almost impossible to listen to. I had to move the tunning MW coil near the center of the ferrite bar to increase sensitivity. Now all stations are tunned with the same level (+/-)

Question:
Analizing the schematic, it seems that the LW tunning coil on the ferrite bar is short-circuited when MW is selected.
Am I right?
What should that be for?
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Old 13th Nov 2014, 12:36 am   #40
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Default Re: Restoring my old Soviet radios

It's not unusual to short out unused tuning coils. It stops any stray resonances which might cause problems on other frequency bands by absorbing signals.
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