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#1
Posted to rec.audio.tubes
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Newbie/visitor wants advice
Hi folks, I've been reading this group for about a week to see if it might be the right place to ask a couple questions I have. But the volume is pretty low, (and at least half has been...um...unpleasantly off-topic. I know, it's the nature of USENET.) so I haven't been able to figure y'all out yet. Here's my problem: I have a 1946 Bendix phonograph/radio which has stopped working. It has tubes in it, which is why I came here. I already have a couple of fine hobbies, so I'm not looking to add "vintage radio repair" to my list of enjoyable pastimes. However, I would like to repair my Bendix, so that I can listen to my 78's and tune in the shortwave. (Perry Como and the Andrew Sisters as God meant them to sound.) Is this a place I could discuss issues that come up while I try to repair my Bendix? Can anyone suggest a more appropriate place? Got any pointers to sources of information on how vintage radios work and how one might repair one? Got any other great advice? Bart (Austin, TX) -- Cheerfully resisting change since 1959. |
#2
Posted to rec.audio.tubes
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Newbie/visitor wants advice
On 8 Jun 2009 13:57:32 GMT, Bart Goddard
wrote: Hi folks, I've been reading this group for about a week to see if it might be the right place to ask a couple questions I have. But the volume is pretty low, (and at least half has been...um...unpleasantly off-topic. I know, it's the nature of USENET.) so I haven't been able to figure y'all out yet. Here's my problem: I have a 1946 Bendix phonograph/radio which has stopped working. It has tubes in it, which is why I came here. I already have a couple of fine hobbies, so I'm not looking to add "vintage radio repair" to my list of enjoyable pastimes. However, I would like to repair my Bendix, so that I can listen to my 78's and tune in the shortwave. (Perry Como and the Andrew Sisters as God meant them to sound.) Is this a place I could discuss issues that come up while I try to repair my Bendix? Can anyone suggest a more appropriate place? Got any pointers to sources of information on how vintage radios work and how one might repair one? Got any other great advice? Bart (Austin, TX) Well, on the off-topic issue - I think you will find that if you filter off everything that originates in Googlegroups, you will see pretty well none of it. Now - to the valves. The easy stuff comes first. Do they all light up? If yes, if you leave it on for an hour or so, do they all get similarly warm (do turn off for a few minutes before trying this one). Next, do you get any sort of faint hum from the speaker? Does it get louder when you turn the volume control up? Do you get loud crackles when you move the waveband change switch? If the answer is yes to all of these, then in all probability the valves are all more-or-less working - although they may well no longer meet their original spec. You will then have to start looking at things like capacitors. What follows depends a great deal on how technically competent you are with a meter and oscilloscope. And of course whether you have managed to find the schematic. d |
#3
Posted to rec.audio.tubes
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Newbie/visitor wants advice
On Jun 8, 9:57*am, Bart Goddard wrote:
Is this a place I could discuss issues that come up while I try to repair my Bendix? *Can anyone suggest a more appropriate place? *Got any pointers to sources of information on how vintage radios work and how one might repair one? Got any other great advice? Bart: For that item, you want to go to: rec.*antiques.*radio+phono The S/N ratio there is much better, and whereas we have our characters, there is far more dedicated knowledge to be found there on vintage tube devices than here, by a large margin. This is more of an audio group with, therefore, a much narrower focus. Peter Wieck Melrose Park, PA |
#4
Posted to rec.audio.tubes
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Newbie/visitor wants advice
wrote in message ... On Jun 8, 9:57 am, Bart Goddard wrote: Is this a place I could discuss issues that come up while I try to repair my Bendix? Can anyone suggest a more appropriate place? Got any pointers to sources of information on how vintage radios work and how one might repair one? Got any other great advice? Bart: Here are some links you may find useful: http://www.justradios.com/#B http://www.dxzone.com/catalog/Antique_Radios/ http://www.tubesandmore.com/ http://www.radiolaguy.com/resources.htm#service%20data Jim |
#5
Posted to rec.audio.tubes
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Newbie/visitor wants advice
Bart Goddard wrote: Hi folks, I've been reading this group for about a week to see if it might be the right place to ask a couple questions I have. But the volume is pretty low, (and at least half has been...um...unpleasantly off-topic. I know, it's the nature of USENET.) so I haven't been able to figure y'all out yet. Here's my problem: I have a 1946 Bendix phonograph/radio which has stopped working. It has tubes in it, which is why I came here. I already have a couple of fine hobbies, so I'm not looking to add "vintage radio repair" to my list of enjoyable pastimes. However, I would like to repair my Bendix, so that I can listen to my 78's and tune in the shortwave. (Perry Como and the Andrew Sisters as God meant them to sound.) Is this a place I could discuss issues that come up while I try to repair my Bendix? Can anyone suggest a more appropriate place? Got any pointers to sources of information on how vintage radios work and how one might repair one? Got any other great advice? Bart (Austin, TX) Hi Bart, Unless you try to learn a great deal about the electronics from before 1959, you will find it difficult to repair your Bendix. I bet it has multiple problems. If I were you I would track down a local repair person who understands tube electronics and who like you is aged over 50. Unfortuately such people are few and far between with many having been rostered on for duty to keep the audio systems going in Heaven. Basic problems with ancient tube audio have been addressed in numerous postings in this group over many years. Perhaps you may care to read the Google Groups archives, just do a search and you'll get there. Its tedious to read old discussions because after 4 postings the subject can change completely, and your exact problem hasn't been anwswered. Old books are another good source for old radio-gram repairs, so you should visit all the second hand book stores and look in their technical sections. Patrick Turner. |
#6
Posted to rec.audio.tubes
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Newbie/visitor wants advice
" wrote: On Jun 8, 9:57 am, Bart Goddard wrote: Is this a place I could discuss issues that come up while I try to repair my Bendix? Can anyone suggest a more appropriate place? Got any pointers to sources of information on how vintage radios work and how one might repair one? Got any other great advice? Bart: For that item, you want to go to: rec.*antiques.*radio+phono The S/N ratio there is much better, and whereas we have our characters, there is far more dedicated knowledge to be found there on vintage tube devices than here, by a large margin. This is more of an audio group with, therefore, a much narrower focus. Indeed you are quite right. Patrick Turner. Peter Wieck Melrose Park, PA |
#7
Posted to rec.audio.tubes
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Newbie/visitor wants advice
Patrick Turner wrote in
: I'd like to thank you folks for all the helpful responses. Well, all but one: If I were you I would track down a local repair person who understands tube electronics and who like you is aged over 50. I ain't over 50, so unless you like looking at the ceiling while choking on your own blood and teeth, you'll need to learn proper respect for those of us in our mid forties. So pull your pants up over your butt crack, shave off the green mohawk and lose the nose rings, whippersnapper. I won't turn 50 until way, way later this year. It a long way off. "Over 50" indeed. The only thing "over 50" about me is the number of one-handed push-ups I do every morning. And I use the other hand to hold the cigar. Meanwhile, thanks to you guys and some other sources, I've come up with a set of schematics, and yesterday managed to get the radio going. It wasn't too complicated, since there are only 6 tubes and they're pretty much in series (complicated a bit by the phono line coming in), so it wasn't hard to figure out which one wasn't performing with my multitester. Then, luckily, cleaning the foot of dust off it and reseating it firmly a couple times did the trick. I'm always impressed by the room-filling sound of these console radios. Not loud, not stereo, but "full" and clear. The only problem is that there's nothing worth listening to on AM anymore, and it seems like there's been a drop off of shortwave broadcasting in the last 20 years. My big dilemma now is that I've figured out what stylus will work with the phonograph, but it requires a set screw, which is missing. I sure hope I can find a replacement for the screw. Bart -- Cheerfully resisting change since 1959. |
#8
Posted to rec.audio.tubes
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Newbie/visitor wants advice
Bart Goddard wrote: Patrick Turner wrote in : I'd like to thank you folks for all the helpful responses. Well, all but one: If I were you I would track down a local repair person who understands tube electronics and who like you is aged over 50. I ain't over 50, so unless you like looking at the ceiling while choking on your own blood and teeth, you'll need to learn proper respect for those of us in our mid forties. So pull your pants up over your butt crack, shave off the green mohawk and lose the nose rings, whippersnapper. I won't turn 50 until way, way later this year. It a long way off. "Over 50" indeed. The only thing "over 50" about me is the number of one-handed push-ups I do every morning. And I use the other hand to hold the cigar. In your original post you sounded just like someone aged about 75. Unfortunately, on the Intenet, we don't get to meet socially so you shouldn't get upset if I guessed your age wrong. I'm 62, and I don't smoke cigars which is a stupid habit if ever there was one, and I ride 150km a week on a bicycle. I don't need to do 50 one handed push ups. I began to learn seriously about tube electronics when I was about 47 and I spent many many late nights in mt workshop to teach myself about it all from books, and applying what I learnt. This was well before I went on line and before there was anyone else I could talk to about tube-craft. Repairing old radios and radio-grams was one amoung many trades I got at. I later moved on to do guiar amps then all manner of hi-fi gear. Now if you are so wonderful as you suggest, then I should think you'll have no trouble at all learning all you need to know to repair old ancient junk like your Bendix. If I could do it without assistance from a news group, so can you. Meanwhile, thanks to you guys and some other sources, I've come up with a set of schematics, and yesterday managed to get the radio going. It wasn't too complicated, since there are only 6 tubes and they're pretty much in series (complicated a bit by the phono line coming in), so it wasn't hard to figure out which one wasn't performing with my multitester. Then, luckily, cleaning the foot of dust off it and reseating it firmly a couple times did the trick. How lucky you were to find only minor problems. I sometimes have to spend a hundred hours of hard slog to get a 1950s radio-gram going properly. It often requires total re-wiring, replacing speakers, re-winding output transformers, re-tubing, and fitting a modern TT on springs and fitting a decent phono amp meant for an MM cart. Often all tubes have to be replaced, and I have to fit a ferrite rod antenna to stop the flurescent lamps we now have from making hum when you tune to a station. The ferrite rod must have just the right inductance to resonate with the tuning gang so that there is good tracking between the tuned station and the oscillator tuning. Then there are the lights and broken dial cord to fix, missing or broken knobs and finally maybe complete french polishing of the wooden cabinet. I've done piles of radio-grams. There was an awful lot to learn. I'm always impressed by the room-filling sound of these console radios. Not loud, not stereo, but "full" and clear. Only when you have got everything working just right. But many old 1950s junk radios sound quite bad and always sounded bad because they have serious design faults The only problem is that there's nothing worth listening to on AM anymore, and it seems like there's been a drop off of shortwave broadcasting in the last 20 years. Come to Oz, we have a few decent AM stations. My big dilemma now is that I've figured out what stylus will work with the phonograph, but it requires a set screw, which is missing. I sure hope I can find a replacement for the screw. If the stylus is a crystal type, you can have troubles with rubber supports going hard or crumbling, and the stylus could be worn. Just about any MM cart on an entry level belt drive turn table made after 1970 will work better than a typical TT from 1955 with a crystal pu. I just re-engineered a big stereo Phillips radio gram and chucked out the heavy old clunker junk TT which was originally fitted in the well for the TT. I installed a second hand AKAI TT from about 1976, and mounted it on the 4 spings taken from under the old TT. The springs prevent the acoustic FB. I made up a phono preamp kit available from a store here. It has a dual oppamp with RIAA eq via a NFB network. It sure sounds a heck of a lot better than when it was made. I also put a 3 way switch in and a pair of additional RCA jacks so a CD player or other source may be used. The list of all of what was done would fill several pages and bore everyone here to death if I included it. The owners were delighted by my results, and so are some of the people like the telephone company and grocer, for now I can pay them. Bart -- Cheerfully resisting change since 1959. I have embraced change since 1959, and I gladly addopted better ways of doing things than were known in 1959. I am glad I have not stayed the same as I was in 1959. I very much like 1950s AM or FM radios which are rewarding to work on. I mentioned to my Phillips r/gram owner that we should always keep something of the past with us so we can remember what the past was like and how we were, and how we were not like. And we then can understand ourselves better now. I designed and built a complete AM radio in 1999 to make sure I could do it, and it performs better than any mass market brandnames from 1955. There is much less noise, less distortion, and audio bandwidth is 20Hz to 10kHz. It is fully tubed. I started this project with the aim to make a "Synchrodyne" set but I found it so difficult I gave up after a month's work and turned the project into a normal superhet, but with variable positioning of one coil in IFT1 so that the mutual coupling could be altered so that the 455kHz pass band could be widened from the usual miserable 7kHz you have with two typical IFTs. This pass band results in only 3.5kHz audio bandwidth. At least this is better than a transistor radio which typically give only 1.5kHz audio because their IFTs are often single windings with a sharp nose on the selectivity curve. Unfortunately I don't make much profit from mucking around with ancient radios. One may easily spend 20 hours on a radio and only get paid $150. At present I have many radios to fix but no time for them. I have just found a guy who likes doing them, so I will give him a try if he is interested. Patrick Turner. |
#9
Posted to rec.audio.tubes
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Newbie/visitor wants advice
Patrick Turner wrote in news:4A2FB14A.2BA19BE1
@turneraudio.com.au: I'm 62, and I don't smoke cigars which is a stupid habit if ever there was one How would you know. Have you ever had a cigar? (A real one, not a cardboard-wrapped, over-blown cigarette.) B. |
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