Blaupunkt Barcelona 2340 - Radio 1956/57. - Page 1
Forum section: electronics / repair

author: DrG
author_rank: Super Contributor
timestamp: July 24, 2021, 08:28:18 pm
content: I am now the proud owner of this fine piece of equipment.The schematic is herehttps://elektrotanya.com/blaupunkt_2340_barcelona_s-n_am-fm_receiver_sch.pdf/download.html(thanks @rsjsouza) and is also inside the radio (wedged under the chassis) (S).I know that this site is not an old radio restoration site and there are many of them out there. I have spent the last few days reading through them and other places. Full on restoration seems to involve replacing all capacitors and more. The radio works and I would like to get it to the point where I could occasionally use it without fear of bricking it. I do not want to sell it.I wonder if I could ask a few basic questions here.1. Can I remove all the dust by careful use of a vacuum cleaner (held away from anything movable) and an artist's brush? Any better way?2. Do you see evidence of prior repair e.g., (1A,1B) the drilled holes under the primary (or was that for heat dissipation?)3. Is the corrosion on a tuner knob mechanism (2A, 2B) and the fuse (6A) and an output jack (6B) a huge problem and a must fix?4. I know that the underside of the chassis contains point-to-point soldered components (4A). I have looked without seeing any huge red flags, but realize I will need to inspect them carefully. I am just not read to remove the chassis...yet.Funny, I had recently called a moratorium on new projects until I finish a ton of current projects - but what was I to do - this walked in the door!Thanks for any help/advice you can give.

author: TimFox
author_rank: Super Contributor
timestamp: July 24, 2021, 08:48:57 pm
content: To start with, I would try to remove as much dust as possible with a vacuum cleaner and brush attachment, to minimize blowing dust around into other places. Then, an artist brush would be good to go after the remainder between tubes, etc. that you couldn't reach. Is the dust oily or dry?The corrosion on the frame of the tuning capacitor: I assume the metal here is aluminum, and the corrosion from damp storage. I would think it would come off with a cloth, but again you want to avoid getting junk into other nooks and crannies.More worrisome would be corrosion on the semi-circular plates that form the actual capacitor, but they look OK from your photo.

author: DrG
author_rank: Super Contributor
timestamp: July 24, 2021, 08:59:15 pm
content: Quote from: TimFox on July 24, 2021, 08:48:57 pmThe dust is basically dry, but it is caked on there and I have yet to make any attempt at removal.That corrosion *looks* like it is on the frame and not on the wheels. It tunes fine on FM and AM, to the degree that it was tested. In fact afaik all the functions appear to be working well - again, I did not want the unit to be on for more than a minute or so.

author: TimFox
author_rank: Super Contributor
timestamp: July 24, 2021, 09:31:14 pm
content: Do you have a smallish vacuum cleaner available? Perhaps if you get the long-handled (medical-type) Q-tip cotton swabs, you can dislodge the caked-on dust into the vacuum-cleaner nozzle. Of course, you are trying to avoid scratching the surfaces, as well as not shoving the dust into crevices.

author: richnormand
author_rank: Unknown
timestamp: July 24, 2021, 09:43:56 pm
content: After cleaning as described in the above posts I would take a close look at what appears to be a scratch on the transformer photo.If superficial or cosmetic all is good. If it goes down to the copper winding it needs attention as you do not want a shorted coil.Next I would check what appears to be a fuse with lots of corrosion on the contacts for continuity.Finally a Variac to bring to voltave up slowly. If OK, reform the capacitors while closely monitoring its behavior.Moving/rocking the valves (tubes) in their sockets with power off and all controls should help too.Then the troubleshooting and restoration starts if it did not come to live. You might be surprised on how these old units are rugged compared to the cheap stuff we have today.Good luck with it.

author: TimFox
author_rank: Super Contributor
timestamp: July 24, 2021, 09:53:12 pm
content: Also, when working on mature test equipment (with tubes) from that era, I find that the tubes themselves are not the most common fault. When ready for test, you might carefully unplug all the tubes and measure the voltages at their sockets, looking for bad screen bypass capacitors (old paper units are hygroscopic) that short out the screen voltages on the pentodes, and similar faults. Of course, the voltages will be higher than indicated on the schematic diagram, with no screen or plate current flowing.

author: DrG
author_rank: Super Contributor
timestamp: July 25, 2021, 01:01:46 am
content: Thanks for the tips so far.I removed a good deal of the dust using a regular vacuum cleaner but with an artist brush guiding the dust directly into the vacuum.I also can see that the aluminum oxide (or whatever it is) will likely come off. You can see the difference in the attached pic vs. the early one. I used a toothbrush (with the vacuum) and was not to aggressive and just staying on that one plate. I need to find out more about what that is exactly and the best way to get it out.Baby steps.

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 25, 2021, 01:16:44 am
content: Careful, if it's a steel chassis it's likely cadmium plated, the corrosion dust is fairly toxic if inhaled.It's generally recommended to simply replace all capacitors (with the exclusion of mica and ceramic) in tube era stuff because even if it works the paper and foil capacitors in coupling positions tend to develop excessive DC leakage with age and throw off grid bias to a point that the tube runs considerably harder/hotter than it should, shortening it's life, and caps are always cheaper than tubes. There's probably at least one paper cap where a Y cap would be called for now, leading to a safety hazard. Old high voltage electrolytics are known to sometimes fail violently.

author: DrG
author_rank: Super Contributor
timestamp: July 25, 2021, 01:30:24 am
content: Quote from: BrokenYugo on July 25, 2021, 01:16:44 amI am aware of the cadmium issues and am being careful (we all have plenty of masks around and I was wearing a dust mask (much thicker for painting and such)) and of course the vacuum cleaner. I don't mind you mentioning it at all though. But, I am not messing with the chassis so far. The piece in question is the housing for the tuning capacitor which has that corrosion - I think it is aluminum but I do not know for sure and treat all this stuff with caution.I was watching this vid:and I am not interested in any of those cosmetic issues, except maybe the cabinet finish at the end. A major restoration is likely not going to ever be done by me. Since this radio works and works quite well, I just want to be able to use it occasionally without a huge fear of bricking it...we'll see how far down the rabbit hole I go

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 25, 2021, 04:16:50 am
content: Magnet test, assume cad if it's steel.

author: DrG
author_rank: Super Contributor
timestamp: July 25, 2021, 05:01:20 am
content: Quote from: BrokenYugo on July 25, 2021, 04:16:50 amgot it, thanksA magnet is not a test for cadmium. X-Ray fluorescence is a test for cadmium. The part in question is the housing for the tuning capacitor and not the chassis. The housing is most likely aluminum. It is NOT magnetic. Aluminum can be cadmium plated.All I have done is removed dust from the radio, using a vacuum to avoid dispersal into the air and while wearing a mask. It is perfectly reasonable to "assume" cadmium plating from a safety standpoint. Cadmium plating has been used for many years. Cadmium is a heavy metal and toxic. Avoid cadmium, whether old NiCad batteries or old radios that contained cadmium plated parts, which are not limited to chassis.Again, it is worthwhile to be on the safe side.

author: KE5FX
author_rank: Super Contributor
timestamp: July 25, 2021, 05:20:10 am
content: I think you'll find that most steel radio chassis are zinc-plated, not cadmium-plated. Cadmium usually has a yellow chromate treatment on the surface. Not unheard-of in radios, but it wouldn't be a huge concern.

author: DrG
author_rank: Super Contributor
timestamp: July 25, 2021, 05:27:55 am
content: Quote from: KE5FX on July 25, 2021, 05:20:10 amIt can also be a grey or white coating. It does not have to be a huge concern but it is a concern and, as I have stated, I am and will continue to treat it as a concern.Here is an OSHA guideline for Cadmium dusthttps://www.osha.gov/sites/default/files/publications/osha3136.pdf

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 25, 2021, 06:52:36 am
content: I forgot to mention I prefer to clean this sort of stuff wet, bit of WD-40 or light oil on a paper towel. The corrosion wipes right off and the oil film helps protect the remaining plating.As I understand it they used cad on all the plated steel parts in old electronics, zinc doesn't solder easy and cad plating in general used to be a lot more common, lots of old hardware was cad plated too.Aluminum can be cad plated but I think that was more of an aerospace thing, where they put that shit on everything.

author: DrG
author_rank: Super Contributor
timestamp: July 25, 2021, 11:52:56 pm
content: I completed all of the cleaning. I don't consider this a restoration to be sure. I did inspect all of the components. I think this is all original! For now, I am happy with this beauty!

author: rsjsouza
author_rank: Super Contributor
timestamp: July 26, 2021, 12:29:49 am
content: DrG, I am very happy for you and glad the offer didn't fall through.The radio is a beauty indeed and, since it works, I would take my time studying its internals and planning the various part replacements - 100% chances they will eventually be needed, especially capacitors and the occasional carbon comp resistor.To clean out these older equipments I find out that pressurized air usually yields better results than a vaccuum cleaner - with the obvious precautions to keep the pressure at an acceptable level and away from the mechanically fragile parts (loudspeakers, for example).

author: DrG
author_rank: Super Contributor
timestamp: July 26, 2021, 01:34:52 am
content: Quote from: rsjsouza on July 26, 2021, 12:29:49 amI avoided pressurized air (duster cans) because of the temperature and because of where all the dust can go, but I get your point.As for the rest, I agree with you completely. It has already been a good learning experience. But, I had to face some facts.....All the caps are replaced in restorations - everything I read has said that and I knew that going in. All of the jacks need to be replaced or treated. Smaller components here and there need replacement (e.g., the fuse). You mentioned an occasional resistor. Additionally, there is lots of string/thread/wire with all of the mechanical works.After all that is done, you have some alignment procedures to conduct and they require a decent signal generator (see blurb attached and the lower portion not in the pic has all the alignment specs).Then, of course, there is refinishing and finding the odd missing clip or what not).One thing that I have learned is that a restored radio actually has very little original equipment. It is anything but original and I understand why.So, there is a great deal to be learned and done with this restoration and I don't want to even attempt it at this point. I don't think it is a beginner's project. For example, take a look at the attached pic - see the top cap - has it leaked? Looks like it to me and I have had caps go bad on me - black goo all over the place...but I don't recognize that white goo and it almost looks like it was placed there as a seal. I don't know, I could try to find out (by asking folks like you), but there is a whole lot I don't know about old radios - I mean for crying out loud, there is no keyboard.What I do think is of great value is that I *think* this is all original. The "extra" holes under the primary may be because this is a US model (I had wondered, but retrieving the included schematic lists it that way, so now I know). Apart from that, I just don't see any signs of repair. Seems to me that all original is what radio folks want. Right now I have that, but if I try a restoration, I don't have that any more.For now, it is fine. A display piece that is pretty to look at and can be listened to as part of showing offIt may, eventually, end up in the hands of someone who knows what they are doing - that could even be me - but not now.That's what I think anyways.

author: TimFox
author_rank: Super Contributor
timestamp: July 26, 2021, 02:57:20 am
content: The bad news is that, after you complete restoring this beautiful piece of equipment, you can't receive the old radio shows.

author: andy3055
author_rank: Super Contributor
timestamp: July 26, 2021, 03:17:28 am
content: Try to source and keep an EF89 and an ECH81 at hand as they can fail easily. That ERO cap and anything like that need to go.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 26, 2021, 11:40:17 am
content: Quote from: DrG on July 26, 2021, 01:34:52 amIndeed; I used to use those cans as well but the pressure is not regulated. Also, due to their cost I was always concerned about using "too much", thus I did not cover the equipment thoroughly. The air compressor helped me with these two points, but there are always pitfalls when compared to a vaccuum cleaner.Quote from: DrG on July 26, 2021, 01:34:52 amYou are approaching this with the right mindset: indeed it is not a beginner's project and taking your time to look into this is an excellent exercise.Quote from: DrG on July 26, 2021, 01:34:52 amThe white residue indeed looks somewhat strange, but I am not entirely sure what it is. Keep in mind this may have been the byproduct of a restoration done decades ago as well - after all, this capacitor is quite different than the other ones surrounding it.Quote from: DrG on July 26, 2021, 01:34:52 amIndeed. It is quite nice to see such a clean radio - even if it was already restored by someone in the past.Quote from: DrG on July 26, 2021, 01:34:52 amThat last consideration is only relevant if you would like to sell the radio at a profit. Sure, take your time to make your mind on what direction you will take, but the pressure to actually touch it is reduced since it is working quite well AND it is very clean.Good luck with your restoration journey and enjoy your radio!

author: DrG
author_rank: Super Contributor
timestamp: July 30, 2021, 12:48:41 am
content: There is a front power on indicator on the radio. It is also a received signal strength indicator.On the left is how it shows the narrow beam when you have not tuned it to a station and on the right, the wide beam when you have tuned it to a station. It's nice. How does a tube do that?

author: rsjsouza
author_rank: Super Contributor
timestamp: July 30, 2021, 02:33:04 am
content: Quote from: DrG on July 30, 2021, 12:48:41 amFluorescence activated by the electron beam inside the tube and controlled by the grid voltage.I love those "magic eyes" or "tuning indicators"One of many articles around the web:http://www.r-type.org/articles/art-137.htm

author: TimFox
author_rank: Super Contributor
timestamp: July 30, 2021, 03:11:44 am
content: Magic Eye tubes are small CRTs: typically, a vane-shaped electrode between the cathode and anode (screen) casts a larger shadow on the screen as the voltage applied to the vane becomes more negative.

author: DrG
author_rank: Super Contributor
timestamp: July 30, 2021, 11:48:55 am
content: Thanks, very interesting stuff. In this radio, it is an EM80 tube.I see projects and even driver boards available - heh.

author: DrG
author_rank: Super Contributor
timestamp: August 08, 2021, 05:03:39 pm
content: Had some time to spend with it recently. Remounted the ferrite. You may have seen it hanging down on earlier pictures, which is the way I found it when I got the radio. It is meant to sit upon this rotatable (front knob) "turret". I had to re-solder one of the two coils and used the schematic for proper placement. The seat for the ferrite does not look broken, instead, it looks like some some kind of adhesive had dried out with age.Right now, I simply used some polytetrafluoroethylene (PTFE) film tape to tie the ends. Any opinion on the permanent solution - Elmer's white glue, hot glue or ?

author: rsjsouza
author_rank: Super Contributor
timestamp: August 08, 2021, 06:05:53 pm
content: Go old school and have your way with parafin wax...Seriously, though, I tend to use something I can remove at a later time (in case of future repairs needed), ruling out something aggressive as cyanoacrilate or even silicone (it heats while curing). I also try to avoid Gorilla epoxy (the one where you mix the two tubes) as I never know if the heavy smell may be indicative of a slow (and possibly destructive/corrosive) chemical release over the years.There is a glue that I tend to use quite often for general purpose and it seems relatively mild: E6000. It cures as a somewhat flexible joint and, in this particular case, it would keep the ferrite (a very brittle material) somewhat protected from mechanical stresses as the glue would dampen any torsion/vibration.

author: TimFox
author_rank: Super Contributor
timestamp: August 08, 2021, 06:06:11 pm
content: Magic eye tubes again:A great encyclopedic reference to vacuum tubes from US, GB, Europe, and the USSR is the “Electronic Universal Vade-Mecum”, originally published in several editions by the Polish publisher Wydawnictwa Naukowa-Techniczne of Warsaw, during the Communist government.The chapter “M” covers magic-eye tubes. To show function, the figure shows a slide-rule dial on a receiver, where “Geneve” is being tuned, ignoring “Warszawa” and “Mockba” (in Cyrillic) nearby, and the corresponding shapes on different models of eye tube for three locations of the tuning dial.