Author Topic: Tento Selena Vega 215 radio  (Read 3748 times)

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Offline Specmaster

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Tento Selena Vega 215 radio
« on: October 29, 2017, 08:11:50 pm »
I purchased this radio on Ebay as a working radio, which it is to an extent. It has some serious damage to the tuning capacitors and the mechanism around it.

Problem is that I can find very little of use to me on the internet about this radio, which in its day was considered to be a good set, not quite a Hacker but certainly not a tin can either.

Does anyone have any experience of working with this radio at all and could offer any advice, service manual in english etc?
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Offline orbanp

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Re: Tento Selena Vega 215 radio
« Reply #1 on: October 31, 2017, 08:55:04 pm »
Hi Specmaster,

I have only seen schematics of the B215 - B216 - B217 radio, various drawings, including the PCBs, but not the Owner's Manual (OM).

It would be the OM that would have the description of the circuits, at least for the older radios (B210 - B211 - B212) it was in that manual. I have only seen those in Russian though.
(The B210 series radios have the exact same architecture/circuitry, except they use Ge transistors, not Si ones, and the audio amp is a discrete circuit, not an IC.)

I have the older B211 radio (with OIRT FM band), and I am fairly familiar with the radio, and would be glad to help.

Peter
 

Offline Specmaster

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Re: Tento Selena Vega 215 radio
« Reply #2 on: November 01, 2017, 03:41:15 pm »
Hi orbanp,

Thank you for your kind offer of assistance with regard to fixing up my Vega 215.

I have copies of the schematics and also the pcb layouts as well as a copy of the owners manual which is all in Russian with the exception of the control layout and the back cover which is in 3 in languages. The information that I'm currently seeking is the precise radio alignment instructions so that if I can repair the damage to the tuning capacitor to provide full scale to be covered, I then want to sort out overall alignment of the radio to restore the full coverage of the wavebands.
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Offline Specmaster

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Re: Tento Selena Vega 215 radio
« Reply #3 on: November 01, 2017, 05:43:05 pm »
I think the tuning capacitor problem may have been solved. I spent some time struggling to extract the chassis from the case and removing the battery/transformer assembly to give access to the tuning gang and had all the hallmarks of someone bending the plates in an attempt to extend the tuning range around the 108Mhz end of the FM band. That resulted in the plates hitting others at the segment slots on that end. Attempted to re-align the plates and it seems at this stage to be successful as long as there is no shorting of the plates, which I'm going to test in a moment.

Assuming it is ok, I'll be reassembling the radio for testing and I think that all that should be required then would be the realigning of the IF and or the detector stage as the sound was slightly distorted towards the tinny edge that we used to associate with those horrible little pocket radios of the 60's and this set is capable of far superior sound. 
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Offline orbanp

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Re: Tento Selena Vega 215 radio
« Reply #4 on: November 01, 2017, 07:13:46 pm »
Hi Specmaster,

I have looked through my collection of documents on the Selena (and Ocean) radios, looks like you have everything for the 215 that I have (or that what is available out there on the net).

I think the tune up of the radio would be like any other radio, with a few differences.
So one would start with the alignment of the IF sections.
In the B215 both the AM and FM IF-filters are concentrated multi-element LC band-pass filters. Because of the interaction between the elements while tuning up, the best way to tune up such filters would be with the use of a sweep generator.

Having tuned up the IF filters, you would tune up the FM-detector. Again, here you would use a sweep generator.

After that you would tune up the oscillator, then the antenna, and finally that the RF stages on AM, on FM there is only the oscillator and antenna circuits, no tuned RF stage.
As the radio is tuned by variable cap, you would start at the low end of the frequency of the band with the coil, and then at the high end with the trimmer caps. Instead of aligning at very ends of the frequency bands, I would set the tuning points roughly at 10% and 90% of the respective frequencies. In this way you would get better tracking between the various tuned circuits.
The above is true for the FM, MW, and LW bands.

The shortwave bands are different, as they have quite a narrow spread, they do not have trimmer caps in the tuned circuits. There you would do the tune up only at the middle of the band just with the coil.

As for coupling the signal for the osc and antenna circuits tuning I would use magnetic coupling. In this case the output impedance of the signal generator would not interact with the tuned circuits of the radio.
On FM I usually just use a short piece of solid wire from the generator as a "transmitting antenna", and so far that has been always enough.
For the AM bands I would use a magnetic loop antenna, I saved the description of such an antenna form the manual of a signal generator from the '50s. (I have not built it yet.)

I do have a bit more detailed tune up instructions for a B211 radio, some of that info is relevant to the B215 as well.
The tuning point frequencies for MW are 600kHz and 1400kHz, for LW are 160kHz and 375kHz.
There are similar frequencies listed for the SW bands, but the band frequencies could be or are different between the B211 and B215 radios.
The other interesting point is that they list two frequencies for tuning up the narrow bands while the circuits there do not have trimmer capacitors either! They probably made some mistakes there...

Another piece of info. I found most of the smaller electrolytic capacitors to be bad in Soviet transistor radios, with increased ESR.
Do check all the electrolytic caps with an ESR meter, that could be reason for the funny sounding audio.

I hope this helps a bit.

Regards, Peter
« Last Edit: November 01, 2017, 07:21:09 pm by orbanp »
 

Offline Tac Eht Xilef

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Re: Tento Selena Vega 215 radio
« Reply #5 on: November 02, 2017, 05:38:16 am »
If I may piggyback on this thread a bit, and ask orbanp a question...

I have a couple of Vega (???? / Berdsk Radio Works?) Selena/??????/O?ean B206/?206 (apologies in advance if the cyrillic doesn't work!) mains/battery portables sitting here awaiting restoration - one working, one not. The working one's in good nick & should come up very nicely; the other is either a very good parts set or mildly challenging restoration, depending on what time of day I look at it :-//  ;). Both were probably sold here in Aus, though they have slightly different SW coverage (e.g. 1.6~4MHz vs 15~15.5MHz).

orbanp, would you be able to assist with any additional info on this model? I've got the NVHR schematic (also found on Electrotanya), but that only covers the battery versions. I don't think I'll have major problems when I get around to restoring either, but any additional info would be welcome ;)

(& here's a pic of the working one)
 

Offline Specmaster

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Re: Tento Selena Vega 215 radio
« Reply #6 on: November 02, 2017, 07:36:37 pm »
I have a schematic for the 215 which has the built in power supply unit and looks like yours could be same chassis with the meter moved across to the other side. PM me with your email address and I'll email it to, it may get you out of jail.
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Offline Specmaster

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Re: Tento Selena Vega 215 radio
« Reply #7 on: November 03, 2017, 03:02:20 am »
Update on progress.

Discovered that one of the three tuning capacitors shorted to ground out when the plates where half way meshed that the MW and LW as well as some SW bands would go deathly quiet so I had to figure out how to get access to the capacitors. Fortunately the construction is pretty basic and simple, poor quality of workmanship abounds everywhere. After disconnecting a few wires and removing some screws success I was "in like Flynn" to coin a phrase.

Nothing looked wrong, I was beginning to doubt my diagnosis until I stuck my bench meter on continuity mode and checked each capacitor in turn and sure enough one was indeed grounding at approx half through closing the capacitor. After a lot of bending a few plates a fraction of an inch  each time, the ground disappeared

Reassembled the radio again and the attached photo shows the level of build quality afforded to it. Tomorrow I'll attempt to do some setting up of the bands and see how we go,
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Offline Tac Eht Xilef

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Re: Tento Selena Vega 215 radio
« Reply #8 on: November 03, 2017, 11:50:15 am »
Hi Specmaster,
Thanks for the kind offer. It looks like Peter has the relevant info & I can probably help him with some other stuff, so I'll decline for the moment.
 

Offline Specmaster

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Re: Tento Selena Vega 215 radio
« Reply #9 on: November 05, 2017, 08:39:30 pm »
Peter,

The info you have given me is a great help although I don't have a sweep RF generator.

I have managed to get the MW and LW bands back again working and attempted to tune them in a bit better but because of all the electrical noise generated in the house I had to resort to going outside to do a test on the bands and they are both working pretty well really. I'm puzzled by the trimmers and coils on the cards for each band in the turret tuner, only one of the coils and trimmer caps seems to be working on both MW and the LW cards, what are the other ones on those 2 cards for and how do you adjust them as I cannot get affect the sound or the tuning on the them apart the ones that do make a difference?

FM is working better then it was after I played around with the adjustments in the FM can although it is still someway from as sensitive as I'd like it to be or indeed think it should be.

I have yet to pull the electrolytics and check them for capacitance and their ESR values, I do that hopefully tomorrow and also check on the transformer taps for the mains power unit as it get really hot and smelly then blows the fuse so I'm wondering if it is set for 120v and the voltage regulator is working overtime keeping the electronics happy while the transformer and smoothing caps cook slowly  :popcorn:
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Offline orbanp

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Re: Tento Selena Vega 215 radio
« Reply #10 on: November 06, 2017, 01:16:34 am »
Hi Specmaster,

Glad to hear that your radio is alive!

If you do not have a sweep generator, I would leave the IF-filters alone.
If you can not resist tweaking them, at least mark the original positions so that you could bring it back to the original settings if things do not go as hoped.

It seems I did not look close enough at the various band coils, it looks like that some of the SW bands, the ones that cover a bit wider spans (75m-180m, 41m-50m), they indeed do have trimmer capacitors as well! Tune them up similarly as suggested for the MW and LW bands
For tuning up the bands you would need a signal generator, hopefully you have that.
Adjusting the radio just by ear, using only stations, is not suggested, this radio is way more complex to achieve good results that way!

When I mentioned using an ESR-meter to check the electrolytic caps I meant using one that can be used in circuit, no need to pull the caps. I would not pull all the electrolytic caps for ESR checking, if you have a meter that checks the ESR out of the circuit, only the ones you suspect.

Here is a good site on ESR-meters: http://kripton2035.free.fr/esr-repository.html.
I built the 555-timer based circuit, for a fixed 70kHz frequency, to be used with a scope: http://kripton2035.free.fr/analog%20esr/esr-scope.html
One of the most useful test equipment that I have!

Regards, Peter
 

Offline Specmaster

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Re: Tento Selena Vega 215 radio
« Reply #11 on: November 06, 2017, 01:33:31 am »
Hi Peter,

Thanks, surely measuring ESR in circuit is fraught with parallel problems of other components having an effect on the capacitor under test? For example, caps on a power rail their esr reading will be distorted by also reading their esr which will be seen as parallel capacitors and therefore their ESR's will be effectively work resistor parallel circuit and will be a false reading. Be certain of a reasonable result, surely it would be best to pull one leg out of circuit and measure in isolation?
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Offline orbanp

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Re: Tento Selena Vega 215 radio
« Reply #12 on: November 06, 2017, 03:07:06 pm »
Hi Specmaster,

Actually, that ESR meter works just fine with in-circuit capacitors! That is the beauty of it!
The measuring voltage is so low that it would not effect semiconductors. The ESR value of an elco is also so low compared to other resistors that might be parallel with that cap that they do not have much effect.
The bottom line is that it does work very well in practice!
Still, I am pretty sure you can find and/or devise a circuit where the measurement results would be questionable...

This is the web-page with the ESR meter that I built, I did find it in a web archive:  http://archive.is/301HS
It has lot more details on it than that web-page I referred to in my previous post.

There is also a very nice ESR-meter design here on EEVblog (there are lots of other designs on the net as well), with simulations and lots of other good info on ESR, check it out: https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/msg341177/#msg341177

Regards, Peter
« Last Edit: November 06, 2017, 03:13:23 pm by orbanp »
 

Offline Specmaster

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Re: Tento Selena Vega 215 radio
« Reply #13 on: November 08, 2017, 11:52:34 pm »
Help, while replacing some of the caps, one 2uf had an ESR of 38 ohms and 50uf read as a 38pf and could not find an ESR for that, I managed to let the soldering iron run away from me and burnt through the tuning cord  :palm: Does any know how the cord is routed on this set at all? None of the schematics etc that I have been able to find on line have any details of this vital information, nor the length of replacement cord I need to locate  |O :scared:
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Offline Tac Eht Xilef

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Re: Tento Selena Vega 215 radio
« Reply #14 on: November 09, 2017, 02:48:18 am »
The Russian manuals for the Selena 210, 211, 212 & various Okean models on this website have stringing diagrams.

Don't know how close they are but I'd imagine they're very similar, if not identical, to your B215. They certainly look the same as what's in my B206's.
« Last Edit: November 09, 2017, 02:50:24 am by Tac Eht Xilef »
 
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Offline Specmaster

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Re: Tento Selena Vega 215 radio
« Reply #15 on: November 09, 2017, 04:52:49 pm »
The Russian manuals for the Selena 210, 211, 212 & various Okean models on this website have stringing diagrams.

Don't know how close they are but I'd imagine they're very similar, if not identical, to your B215. They certainly look the same as what's in my B206's.

Thanks for the link, it's kind of helpful. I only found 2 of them with stringing info and then that was sketchy as they don't tell you how much is required so I've ordered  3M of the cord which is more than enough, but at least it will allow to have a second go at should I screw up the first time  :scared:

One thing I have come to realize is that my radio says its a Vega 215 on the fascia but on the inside of the fascia it says B215 and I've also noticed that my LF or audio amplifier and power board is NOT the one depicted in all of the schematics that I have so far come across  :-//

I have also located a proper service manual, hopefully its in english and is complete.  :popcorn:

EDIT.
I have just had it confirmed that it is the full manual, 64 pages in English with all the circuits and everything,  :phew: Lets hope that it also covers the amp and power supply board thats in my radio.
« Last Edit: November 09, 2017, 10:52:48 pm by Specmaster »
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Offline Tac Eht Xilef

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Re: Tento Selena Vega 215 radio
« Reply #16 on: November 10, 2017, 12:48:35 am »
I only found 2 of them with stringing info and then that was sketchy as they don't tell you how much is required ...

Don't know if that's as 'sketchy' as you think it is - out of a dozen or so original service manuals for vintage radios I own / have owned, only one specifies the length of the dial cord (it's for an Astor BNS, so Astor collectors may find more). Usually you just have to suck it up and go "ok, so it's x inches long there, y inches long there, has 2 turns round a drum that's about d inches diameter, so I'll need about 2*(x+y) + 2*(pi*d) - plus an inch or so for the couple of turns on the dial knob shaft, and another 6 or so for tying off" ;).

Even 3rd-party manuals like the US Beitman's / Rider's / Sam's, European ESdRI, or Australian AORSM, rarely give the overall length. Heck, Sam's put out books that were nothing _but_ dial stringing diagrams, and I don't think cord length is mentioned for any of them...

Quote
... so I've ordered  3M of the cord which is more than enough, but at least it will allow to have a second go at should I screw up the first time  :scared:

A couple of handy tips: There's 2 common dial cord sizes - "Standard" 0.028" (0.71mm), and "Thick" 0.035" (0.89mm). 'Nano-cord' comes in a variety of similar sizes, has similar grip / non-stretch properties (after giving it an initial pull), is usually a pretty good substitute in most cases, and you can buy 100m of the stuff for the price of 3m of proper dial cord...

Quote
One thing I have come to realize is that my radio says its a Vega 215 on the fascia but on the inside of the fascia it says B215 and I've also noticed that my LF or audio amplifier and power board is NOT the one depicted in all of the schematics that I have so far come across  :-//

I have also located a proper service manual, hopefully its in english and is complete.  :popcorn:

For what it's worth the only model numbering on mine is on the back where it's labelled "Selena F8-TR19-B206".

The actual naming of these things seems to be a mish-mash of transliterated/romanised cyrillic script, translated Russian, and abbreviations. As far as I can tell (& leaving out the cyrillic that the forum doesn't handle):
  • "Vega" appears to be based on the manufacturer, Minsk Radio Works (Belarus). It seems at some stage, prior to Tento being formed, they exported under the name "Belarus Radio Works", abbreviated to "Bera". The actual cyrillic for that would transliterate into roman script as "bena" - but it you ignore that and treat the English "Bera" as more-or-less Cyrillic Russian, it comes out as "Vega". Which is a more Western-acceptable name anyway...
  • "Selena" & "Ocean" are straight translations of the Russian model names.
  • "B215" or "B-215" are translations of the Russian for the model number (which would be transliterated/romanised as "b215")
  • "Tento" is short for "Technointorg", a Russian export trade group formed in the late 70's / early 80's.
So, sticking to the "manufacturer, brand/line, model number" pattern we usually use in the West, it's probably most correctly a "Vega Selena 215" or "Tento Selena 215" depending on age. But the manual would likely refer to it as a B215 chassis;)

They also seem to have made major running changes during productions, so it doesn't particularly surprise me that a presumably late model (based it being a Tento, not a Vega) like yours varies considerably from the original schematic. If it's just the amp & power board, you'll probably find near-matches for both amongst the later models.

(I will say that most of the above is just my speculation based on "research" (aka Googling ;)) over the last year or so. I don't read/speak Russian, I've only seen my two B206's and a handful of others, and don't claim any other special knowledge about Russian radio models or manufacturing, so if someone knows better then please correct me!)
 

Offline orbanp

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Re: Tento Selena Vega 215 radio
« Reply #17 on: November 10, 2017, 11:53:18 pm »
...
I have also located a proper service manual, hopefully its in english and is complete.  :popcorn:
...

Hi Specmaster,

Any chance you could share that manual?
I would be interested in seeing the full service manual.

Regards, Peter

 


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