Blaubunkt 2340 Barcelona schematic and no AM reception

SteveJB · Member Joined: 05 Apr 2009 Posts: 36 Location: New Jersey

Does anyone know where I can get the schematic for this radio?

Also, it works well on FM, but there is no signal (from the eye tube) that I can discern on AM.

There are two jack inputs for a long wire and ground, I do not have a long wire. I would have thought that I could add a short piece of wire in the jack input just to get some reception to see if it works, (like used on AA5'S) but this does not work when I try it.

This is my first German radio and FM as well, so I am completely unfamiliar with it. Is there a better way to get the AM reception? Also does the ferrite antenna work on the AM or the FM? I though they were for the am.

Thanks for your help.
Steve

JoeinRI · Posted: Nov Wed 04, 2009 8:12 pm

Hi Steve,

You can get a schematic at RadioMuseum.org

http://www.radiomuseum.org/r/b ... _2340.html

......BUT, for members only. Not sure what you're thoughts are on joining RadioMuseum.org, Seems to be somewhat controversial subject on the ARF and different strong opinions. If you plan on doing more German radios, I suppose they are the experts! I haven't joined myself....and have managed one way or the other to get the diagrams I've looked for.

As far as the "eye" tube goes....the couple of similar German radios I've done have both needed replacements. Phosphors all worn out...if you're looking for a green eye and can't see it, doesn't necessarily mean you have no signal. I've found that you can get cheaper Russian made eye's for them requiring minor wiring changes.

Your radio is from 1958 and undoubtedly needs a "re-cap"....electrolytics and papers.

The German sets I've done are good performers. Amazing what they could do with few tubes!

Good Luck,
Joe

SteveJB · Member Joined: 05 Apr 2009 Posts: 36 Location: New Jersey

Thanks for the advice. The eye tube works with the FM, not the AM, so I was assuming a poor signal.

I cleaned the chassis up this week as the chassis was very dirty and noticed a cracked tube (EL84 audio out) so I changed it after getting one from AES. The FM was working fine before the tube broke, so I expected it to work again with the new tube.

After turning the rado on today it started to smoke. I burned out what looked like a 2K resistor. I replaced with a 2W one and it still got hot- so hot the solder melted so I shut it down. I did not re-capp yet. I will do that right away, but I am not sure if a shorted cap would do that? Possibly I suppose, if it deopuples and is connected to a power source. That could raise the current quite a bit.

Now I really need a schematic, I'll look into the radiomuseum. I had heard it was expensive, but I may have no choice.

I have two TO's where I have only replaced the rectifier. They work fine. This is a 1958 model (about the same age) like these so I though the caps might still be good on the Blaupunkt.

Marconidevice · Posted: Nov Thu 05, 2009 9:33 pm

Most Blaupunkts use a selenium rectifier bridge. Will not look like an American selenium, it will be in a flat aluminum case with 4 lugs or possibly in a round resin tube on the chassis normally marked "AEG" brand. If the filter caps are bad, selenimun may have a shorted section or two.
If it has brown dipped caps on the chassis, they are probably still good these are similar to our "orange drops" also the clear plastic cased ones with machined looking ends are all likely still good they are well sealed and stable . If it is full of the reddish/white/black paper ones usually marked ERO these are probably leaky.
To work properly, the bandswitch will need to be cleaned very well.
I know it sounds and looks daunting, but I will usually draw a good picture of the layout and wiring and remove the whole bandswitch for a proper cleaning. Its quite amazing how well these sets will work when all of the bandswitch contacts are clean.
When I pull one of these bandswitches out, I will do 1 deck at a time, pulling out the inner contact sections and polishing them with a q-tip and Mothers Aluminum polish. I will clean the actual contacts the best I can by running a piece of brown paper through them (like grocery bag paper) and when done do a light spraying of Deoxit. It would be nice to dunk these in the ultrasonic machine but they are normally loaded with coils.

Mark

Bugman · Member Joined: 14 Mar 2009 Posts: 287 Location: RI

The schematic is in Sam's Photofact 422, Folder 5. Check with your local library. Most have a branch with the Sam's on hand and you can photocopy the set. Good luck.

Pat

majoco · Posted: Nov Thu 05, 2009 9:46 pm

I can e-mail you a copy of my schematic for a Blaupunkt "Sultan" of about the same vintage. They seem to have only a few variations in that era, some have an EL84 and a driver while other have an ECL86 triode-pentode output.

My Sultan tube line-up is ECC85 FM tuner, ECH81 Osc/Mix, EAF801 IF/AM Det, ECL86 Audio driver/PA, EM87 Magic eye, Si rectifier and 2x AA113 diodes in the FM discriminator.

I also have some other Blaupunkt schema's here, so if you give me your tube line-up I'll see if one matches.

I agree with Marconidevice's info - the bandswitch is a problem area - lies horizontally so collects every bit of dust and has some very delicate wiring - the rotating ferrite antenna is suspect too.

Another trap for the unwary is the pushbutton marked "FA" - it has to be pushed in after the "MW" button to connect the ferrite antenna - otherwise you'll be connected to the non-eixistant lonwire!
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Tin Omen · Posted: Nov Thu 05, 2009 11:40 pm

I have a schematic for a Blaupunkt Barcelona 2340 and the alignment, both are in German. Usually a smallish, 1/2 watt, 2Kohm resistor would be going to a IF amp transformer. With a shorted capacitor burning up the resistor.

Send me your email at deathrex@beyondb.com
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SteveJB · Member Joined: 05 Apr 2009 Posts: 36 Location: New Jersey

Thanks for all the advice. I did manage to get a schematic this morning from Sam's.

I started to check the caps near the burned resistor and replaced them since I have plenty on hand. After that, I gave it another try, but it got the replacement hot again. The caps are the shiny metals with the plastic cover. So far the ones I have replaced seem ok. I'll do the rest of them before I try this again. If the caps are good, I dont see what else could smoke the resistor.

Thanks for the advice on the ferite antenna. This may be why I did not get any signal on AM where I tried it.

One last thing, does anyone know if the 10,000pf as stated on the capacitor is the same as a .01mf? I just want to be sure they have the same meaning as my American radios. My schematic has some listed as "10000pf" and some others as just ".01". To me they are the same, but why have differet notations on the schematic if that is the case?

Thanks,
Steve

Tin Omen · Posted: Nov Fri 06, 2009 3:42 am

SteveJB · Member Joined: 05 Apr 2009 Posts: 36 Location: New Jersey

The resistor that burned out looked like it was connected to "A3" based on the chassis bottom view in the manual. They have the transformers A3/A4 in the same can on the schematic. This resistor is connected to A3 from the schematic. I have not changed out the .025 cap yet. That is next.

I have a 2W resistor in its place (it is what I had). That is probably not good as something else may burn since it has a higher rating than the original (The original is much smaller, not sure what the watt rating is). I will change that out also. What watt rating should I use? The resistors are pretty small. The 1W,25K next to the one that burned is very big by comparison.

Thanks for your help. I really want to get this working! I have heard so much about the great sound these have.

Ross Hochstrasser · Posted: Nov Fri 06, 2009 10:47 pm

Your AM problems are most likely capacitor problems inside the IF cans. I have rebuilt many Blaupunkt IF transformers and can give you some pointers on doing so. Get the rest of the radio recapped first. Good Luck!! Ross
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SteveJB · Member Joined: 05 Apr 2009 Posts: 36 Location: New Jersey

I should have the recap done this weekend. I still have the short however, even though I changed out all the caps in that area and dont see any crossed wires.

Did you mean that these am transformers are prone to be silver mica diseased?

Thanks

Ross Hochstrasser · Posted: Nov Sat 07, 2009 3:06 am

Hi Steve, Yup it's either silver mica disease or a deterioration of the contacts on the silver plating. There are 2 silver plated fingers that contact the plating on the mica and with temperature changes the plating wears through. I remove what's left of the old caps and install new ones outside on the terminals. 150 PF on the input and 250 PF on the output. Bear in mind that if the EL84 is out of the radio, B+ is going to be unusually high, your short could be a result of that (maybe??) I would also look at the paper caps downstream of the 2K resistor. It only takes one shorted cap to take out the resistor. There is also most likely a 50UF electrolytic after the 2K as well. (part of the main filter cap in the power supply. ) I should have the schematic, I'd be happy to send you a copy by snail mail as my scanner is crummy. Thanks, Ross
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Tin Omen · Posted: Nov Sat 07, 2009 3:08 am

SteveJB · Member Joined: 05 Apr 2009 Posts: 36 Location: New Jersey

I just finished a total recap and it is working great. No more short.

No I just can't get any AM. I an not sure where to start toubleshooting. The eye tube doesn't show any signal, the way the FM does, so I am not sure if that means I have a problem with the front end.

Is there a way to troubleshoot the transformers?

Thanks to everyone for your input.

Steve

majoco · Posted: Nov Sun 08, 2009 6:41 am

Keep on testing until you are sure..... Very Happy

Does it have a rotating ferrite rod antenna? Those wires are very fragile and prone to breaking.

Have you attached a long wire antenna? If the "FA" switch is not working, then the ferrite is not connected.

If FM is working, then all the windings on the AM IF transformers are OK, as they are in series with the FM IF's.

Clean the switch bank. Again......
_________________
Regards - Marty ZL2MC

Ross Hochstrasser · Posted: Nov Sun 08, 2009 2:00 pm

Feed 455(or maybe 465, I'm not sure) kc into the EF89 tube by wrapping a wire around the tube, if you get signal out of the speaker, then the 1st IF transformer is bad, If you don't the 2nd is bad. I would just shotgun rebuild both of them, because if you don't do it now, you will be after a few dozen hours of use. I have restored many of these Blaupunkts, The IF cans are bad. (only the 455 kc ones, the 10.7 mHz are OK) Ross
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SteveJB · Member Joined: 05 Apr 2009 Posts: 36 Location: New Jersey

I am using the radio today and notice that I can get AM on the ferrite at very low volume and with the long wire, a little higher, but still very low volume.

On FM the volume is varying, but is clearly audible. It goes from loud to louder then back intermittently. My eye tube appears weaker compared to what it was earlier.

Does this sound like stmptoms of particular problem?

Also the switches may be dirty as I noticed the AM switch, if pressed gently while it is turned on, will cut the reception that I do get on and off. FM does similar, altering volume as I press it repeatedly.

I know there is supposed to be a selenium rectifier in the power supply. Is this a potential problem like it is in other radios?

Ross Hochstrasser · Posted: Nov Sun 08, 2009 5:57 pm

Definitely clean the switches with DeOxit or equivalent, Yes the selenium rectifier is a problem, it is sometimes located on the dial sub panel. (behind the glass) Replace it with a silicon bridge with a 400 PIV rating, amps are unimportant, as the current draw is less than 1 amp. Be sure to put a 100 ohm 10 watt resistor in series with the+ lead. If you're getting AM weakly, try turning the slugs (VERY CAREFULLY, they can break) in the IF cans (the ones with the wider slots in the slugs) and see if there's an increase in signal. This may fix your problem, albeit temporarily. Good Luck!! Ross
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"If you throw it through the window,you have to fix the window too!"
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SteveJB · Member Joined: 05 Apr 2009 Posts: 36 Location: New Jersey

Hi,

I did tune the slugs on the 460kc transformers today and the volume is up, but not as loud as I think it should be. There are two antenna coils, A16 and A17 that are listed as "1500kc & 546kc BC ANT". These seem to have a trimmer on them. I did not touch those.

You can hear AM fine in a small room, but it is too low volume for a large room., nothing like the FM, which is very loud.

I did notice that the strongest stations are ok, the best being 570 (in NY). Problem is that I hear that station all along the lower dial up to about 700kc. Does that sound like a common symptom of a particular problem?

It's close to working right, but not quite there.

Thanks for all your help so far,
Steve