STUNNING 1960s B&O Vintage Radio - BEOMASTER 900K - Can I FIX it?
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- Опубликовано: 2 окт 2024
- In this video I attempt to repair the first mains powered transistor radio/amplifier from Bang & Olufsen. It cost a small fortune back in the 1960s and was quite cutting edge apparently. I purchased this faulty from eBay and unfortunately it became even more faulty during transit!!!
It is an absolute beauty in terms of looks and engineering. Can it be made to work again. Let's find out.
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Remember that this is just for entertainment and I am not an expert in these repairs. The processes in the video may not be the best way, the correct way or the safest way to fix these things. I do love fault finding and trying to fix broken things, so I hope that comes across in this 'Trying to FIX' series. Many thanks, Vince.
Some radio rebuilders put the modern capacitor inside the old can to keep the appearances the same.
Great idea 👍👍👍
Need to recap my Heathkit W5M mono amp, most difficult part will be opening the cans to put new capacitors in.
They’re a main aesthetic of that amp.
Whoops, replied on wrong comment thread.
never worry about the videos being too long Vince we will watch no matter what
Thank you
there is not such a thing as too long video. Only viewers with patience too short.
No, there is no danger of that when the video runs at 10 X speed. Thumbs down for that.
100%
Make them a bit longer. 😊 Tbh I get totally engrossed. If you put these on at the cinema I'd go and see them.
That bridge rectifier makes 50 Hz to 100 Hz as it "flips The negative side to positive" and there was a spike at that frequency. 200 Hz was just a harmonic multiply of it.
Yeah, there's a big peak at 100Hz too, and there's a whole bunch of additional harmonics clearly visible above 200Hz too. I suspect the reason the 100Hz peak is lower than the 200Hz harmonics is either because the speaker falls off at low frequencies, the app tries to approximate hearing sensitive or that the mic in the phone is less sensitive down low (might well be a combination). Other than the 100Hz being a bit low the sequence of harmonics peaks is exactly what should be expected.
Close, but no cigar it's all about the diodes and how each contribute a 50 Hz signal to the supply rail.
@@KorAllRBare No, he's exactly right. A full bridge rectifier doubles the input frequency of the input AC, IE 100Hz or 120Hz. Which is why there's a significant peak at 100Hz that MMV didn't notice because the 200Hz "first harmonic" peak was higher due to the equipent and/or speaker he used.
Well maybe you're right@@Torbjorn.Lindgren it's well over 48 Years since being schooled on rectification and the umpteen configurations utilising inductors, diodes and capacitors dealing with unwanted noise and possible harmonics, but I do remember how that 200Hz is to be expected, and I am pretty sure it's a lot to do with the timing in reference to each transformers secondary winding inductances and it's Va and at what point at any given moment each diode is conducting the inputted rising and or falling Voltage/Current comparative to all other secondary outputs that may or may not be in phase and thus adding to our supply rails design considerations.
Indeed, the mobile phone Mic is not setup to pickup lower frequencies in that range. So the harmonic is more prominent in the spectrum analyser. You would see the 100hz if you used the frequency range slider on your mini scope.
Mitropa is a German short for Mitteleuropa (Middle Europe). Officially Mitropa was a company exploiting dinner and sleeping cars on European train routes since the 1910's but in the 1950's and 60's it was also used as a short for the mid Europe area. As in that time Europe was divided by the Iron Curtain and B&O was focusing on the Western European market the Mitropa area only shows on the panel only stations from Luxembourg/Belgium/Italy/The Netherlands/Austria and Switzerland.
The sound at 1:07:25 is a data signal. Can be anything but most likely digital communication between a main building and a remote installation of a factory somewhere near you.
It's morse. Probably on the ham bands.
RIP Steve Wright, for me and my age it was Steve Wright in the afternoon and his Mr Angry and all the other characters, if anyone remembers.
Vince, you played the Sleepaway Camp - The Trick, and you last played it from my memory during lockdown, hits me every time, no one ever called me, unless they wanted something and I am fine with that, sad but fine. The royalty-free song hits a nerve about childhood and then adulthood reality. We all live in a version of our own world vision.
You do great fantastic inspiring videos and fixes, make them as long as you like, and I will always watch them. Thank you. I know everyone is saying Morse code and I agree, but now I am thinking about what frequency, if it is possible to hear, can you hear encrypted comms and if you can hear it long enough then you would be able to decrypt it if you can guess or find the key. back in the day, not so much now I am guessing. Cannot wait until the next one cheers!
"I tell you what boy!" I remember :-)) I also remember our house having the Beomaster 1000, which was the same but with no speakers - a tuner-amp.
Yes i remember, i was working in a garage in the 80s listened to Steve Wright, Mr angry was my favourite character.
Nice Job Vince 👍 I was thinking it sounded like mains hum. To keep the insides looking authentic you could have always soldered the replacement cap inside of the old one seeing as you removed all of the insides of it 🙂 And it was fantastic that it had the schematics in it! Very rare to get a schematic of anything these days 😢Great job as always.
Thank you Mick, great idea on the cap inside the cap. I wish I had done that. Next time 👍👍👍
The electrolytic caps are 60 plus years old. Don’t play with them, just replace them as a matter of course.
They're probably leaky best to replace all the caps with modern ones for extra reliable performance ❤
Finding that envelope was a gem! Wish they'd still give out schematics with hardware! Awesome fix, Vince!
Lovely isn't it, and in such good condition as well 👌
@@Mymatevince I have a Beomaster 3000-2, and also an envelope with the schematics inside, probably B&O used to do this more often, caps need to be replaced.
I would love to see the other piece of paper that was in there - it looked like a letter? Probably something along the line of "Thank you for buying this"!?
Since when was IP a thing? Probably when one started copying from another. And that was the end of those marvelous schematics.
@@habana7638 many audio brands from this period did this it's not a b&o thing. Caps need to be replaced for longevity but you shouldn't expect a massive sound improvment upon replacement. It's more so a peace of mind thing then an audible improvement in most instances. If you have vintage speakers replacing the filter caps can make a massive difference though.
Greetings Vince. I look forward to your clips in which you eliminate possible malfunctions with ease and knowledge, and what separates you from other masters is that you give advice and show how you personally work. Just continue with your work and all the best to you and your family in this year 2024. A lot Greetings from Sarajevo, Bosnia and Herzegovina
Thank you. All the best to you and your family too👍
finding a schematic diagram inside device was 10/10👌
I wouldn't expect it to sound great with those speakers but I absolutely love the look of it!
.....The Ali tubes with screws sticking out are 'beehive' trimmer capacitors..They are for alignment, don't twiddle willy-nilly!! Feeling my age!!!! :-)
Beat me to it!
Thank you Fred👍
200Hz (199Hz) is the 4th harmonic of 50Hz - I'm guessing the receiver picked up the harmonic as the main filter caps weren't working. With any kit of this age - you can almost guarantee the caps will have failed.
Thank you
Also the bridge rectifier was working so that would double the frequency to start with. Speaking of the caps that one just above the corroded fuse looked a bit suspect - it could have leaked onto the fuse if it was stored in that orientation. I think I would look to replace all the caps at least in that area and you may find it sounds a lot better.
Great fix mate, and the videos can never be too long. That brown/tan shoe polish you get in squeesy bottles with a sponge covers up bright spots and damage really well btw.
Great job Vince! I love restoring vintage audio.
Seeing these old beauties come back to life is so satisfying
I've been a ham since 1991, and I agree with CS6PY from Portugal that you heard CQ CQ. Morse code or continuous wave (CW) requires very little bandwidth, so you simply heard many hams communicating or attempting to communicate on many different frequencies at the same time. CW is an extremely efficient way to use bandwidth so you tune to a very narrow frequency range and use an extremely tight filter compared to voice (aka phone) to chat. Today's ham radios are absolutely amazing and cost many thousands of dollars but you ran into what sounded like pretty favorable conditions. 73 DE N8QDW.
Or you can get into the hobby on 2m for £30, or 10m for £150.
... The power supply capacitor has a 'ripple current' rating, important for smoothing & power supply capacitors, Vince!! Your replacement may not last too long!! look on the 'better' sellers websites, ( R.S, Mouser etc } and look at the specs of the capacitors. I find, as modern day capacitors get smaller, if you get one roughly the same size as the one you have taken out, at the same capacitance value, a modern one has more 'ripple current' rating, so would be just fine !! { Cheers, Fred 50 years tv & video engineer }
Take Note, Vince!!!!
Mitropa are probably "mitt- Europa" aka middle Europe. The cabinet are teak, I think.
EKS means extra (Danish=ekstra) speaker. It's possible to have a kitchen speaker, so the lady of the house, can hear the same as the father and the son in the living room.
Pretty cool, thanks!
And you could plug in the external speaker plugs on two ways: one direction to switch off the internal loudspeaker and the other direction to keep it connected.
Some brands offered an external speaker box with the same design as the build-in speaker.
By adding only one box you could "widen" the stereo effect in the room.
No not teak or any kind of natural timber the case is made from laminate covered chipboard.
@@philcollins7701 Teak veneer, but real Teak. It is definitely not vinyl. I have several B&O from the period. It fits with the Danish design standard.
Ok maybe teak veneer but a chipboard core the restriction on imported teak was coming in about this time and the case would have been to costly made from solld teak.
Those signals you were querying at the end are CW (morse). I imagine the receiver covers the 40m amateur band (7000 to 7200 kHz) band. CW is found at the bottom on that band.
I think you're correct, other than the band... It's probably Morse the bottom end (1.81MHz - 1.838MHz) of the 160m band judging by the dial scale. This is a wideband broadcast AM/FM receiver and doesn't have the narrowband filter required for reception of individual CW stations... Interesting that the BFO managed to pick-out CW though. 73 DE 2E0PTY
I was gonna say it sounds like PSK-31 or something like that
I was thinking it sounded like a data mode of some description, but the suggestion that the receive is wide band does seem plausable of multiple CW transmissions.
Psk 31 or psk 62 teletype or telex thre are computer programs that can decode it
It looks absolutely beautiful. What a treasure! What a delightful find! That envelope and the no hum made my ear lobes tingle with delight! Amazing! Loved it! Thank you for sharing!
I gave "Mitropa" a look myself as a geographical term and the closest I could find was a German shorthand for "Middle Europe." Following the row I can recognize Luxembourg and Brussels, so I think that's what it is.
Thank you Butter Ball 👌
Sound more sensible than a National railway company. Thank for finding that out.
Sounds like you've got a positive ground circuit there, which was very common in radios in the germanium era. I guess it made it easier for people to wrap their heads around the circuitry and still draw it the traditional way, with germaniums almost exclusively being pnp devices (which those raised on _vacuum bulbs_ would not have been accustomed to, as those are basically n-channel devices). They went back to positive supplies and negative ground with the advent of silicon which is npn by default.
Vince, I've been watching your vídeos and also learning a lot. Don't want to be a spoiler but the string for the FM was placed conter clockwise. That's why the tunning direction is no the same as the others.
Warm regards from Brazil ( 40c - 105f)
Thank you. I'm gutted I got that wrong. I will restring it and make it work the correct way next week some time. Cheers for letting me know. Enjoy the sunshine 🌞
Perfect excuse for a revisit video. 😁 Changing the string and fitting the new caps in the original cases.
What a well made radio and a great fix.
RIP Steve Wright, Radio wont be the same...
The fancy sound on short wave was an amateur radio contest in morse code. As the bandwidth of the radio is wider than one of an amateur radio receiver you hear many signals in parallel.
I'd like to say I understand this comment 😅🤣
Also, my dad was a Fire Officer, and in the 70’s-90’s you could get the Fire Service in LW, and listen in for his voice. After the telephone went off and he left the house to respond. Great memories.
I think the warbling noise is RTTY (radio teletype). My college project way back was to build some hardware to work with the BBC B computer and write a program to decode it. It was a long time ago and I think there were some other similar sounding signal, but I think it’s RTTY.
Another great video. Curious 56:48 you say "I think it's still going to be noisy" Why? You clearly proved that the main filter cap was completely open. I would have been very surprised if it was still humming.
I have to say - I think the fixing audio equipment has turned out to be my favourite category of fixes. Especially the hi-fi B&O, Grundig etc. Keep it going....!!
Look up mend it Mark if you like Audio repairs 😊
@@wisher21uk Mark must be the most cheerful technician on the planet!
@@adampoll4977 true even when he gets a kick off of the capacitors he has a laugh lol
Watching Vince's excellent work after hearing about the untimely passing of Steve Wright is all a bit surreal..!
HI Vince...
Nice job...but you have made a mistake .....The FM wire is wrong..if you turn the fm tuning knob to the right ..the needle also has go to the right ..turln left ...needle goes left.
To fix this you have to loosen the wire again and wind this cable on the other side of the tuningknob ( reverse the way in/out at this knob )
Then... all the blue electrolytic capacitors are all rotten..change these and the sound and sencitivity will be much better.
Greetings.. Dirk from Belgium
I would be replacing every capacitor for sure, but for someone who doesn't listen to radio much it would be a waste of money and degrade the originality of the vintage piece. The better option might be to solder in a bluetooth module, because the amplifier stage sounded pretty clean with the line input.
My previous comment was unfair sorry..I deleted it.Well done Vince...good job....the radio looks good on the cabinet you placed it on.
The one I repaired was the same model, but without a speaker. I repaired it because the magnet on the tuner or level meter had fallen off, and the wheel did not rotate because the pulley grease had dried out. The sound was good.
The hum is likely a bad rectifier filter cap, which passes some 100 hz from the rectifier.
Also, be careful with that mineral wool; if it was made before the late 80s/early 90s, it will VERY likely contain asbestos and not just make you itchy.
The corrosion on the fuse holder is very likely galvanic corrosion which happens over time between some combinations of different metals. Pretty common to see this on fuse holders of vintage electronics.
Then i shuld be dead, no need to worry
No, the 478uF reading on the smaller 400uF capacitor doesn't suggest it's OK, it suggests it probably LEAKING which results in the multimeter giving a too high (wrong!) capacitance reading!
Basically, the multimeter calculate the capacitance based on how much power it needs to send into the capacitor to reach a set voltage, if the capacitor leaks it needs to provide more power, juas AS IF the capacitor had a higher capacitance. So it's just as much warning flag as a high ESR is. Unfortunately most instruments doesn't detect this even though it would be trivial to check for (does the voltage go away quickly once it stops charging? - if yes something is leaking and the capacitance measurement is bogus and if it's out of circuit the capacitor is the leaking/broken part).
Well done Vince ! 😊you also made that look like brand new.
The "EKS" stands for "ekstra" - danish for extra. It´s just an unswitched clone of the left speaker channel and was intended for an extra speaker in i.e. the kitchen.
My father had one of these back in the 60's-70's.
at 11:55 you're wondering about the speakers, they are made by sinus.
at 32:50 you're wondering about the pointy round things, they are tuning capacitors. Turning them changes their capacitance because internally they are made up of concentric non-touching ring to form an air capacitor. Turning them makes these rings go further inwards or outwards thus changing the overall surface with air between them and so changing the capacitance.
Svenska Högtalarefabriker
(Sinus). You can see the S are modeled after sine waves.
Thought I was watching Mr Carlson's Lab for a minute
Having watched Mr Carlson I wonder what he would think of the lack of a variac power supply....
This is a bit modern for him.
Or the rather excellent “mend it mark”
"Mr. Carlson" is dreadfully overrated, pretentious, dry, and boring.
@@QuadMochaMatti then don't watch? If your career/speciality revolved around old radios and just radios in general, I'm sure you'd seem boring to most people too! :D
Hi Vince. Another satisfying fix!
I'm not sure about that 199HZ reading. It sounded like classic 100HZ hum, which would be expected with a bridge rectifier supply with duff smoothing.
When he showed it in the spectroid app you could see that there was also a 100hz hum!
You might have put the new cap into the old big can for ascetics. Otherwise, nice fix!
dont know that much about whats sorts of radio gear is used in your area but that sound @1:07:20 is some sort of digital mode transmission. think like modern emergency services police etc. if you catch those signals on analogue reciver it will do something like this since it treats it as a normal sound singnal not as the correct digital mode it is and even if it could its very likely encrapted.
You know it's world radio day over there at the time you uploaded this video, that's pretty good timing Vince.
Nice work Vince it looks lovely, it’s great how you can make everything you fix interesting to watch. Keep up the good videos and wish you all the best!
Thank you so much 😎
That sound at 1.07 is CW aka morse code which is for used by the amateur radio community. Also down on that band is RTTY which is also used by the same guys but is computer generated. This frequency is known as top band.
If you think about the bridge, and the 4 diodes - that is what gives you the approx 200Hz (4 x the 50Hz AC) - the reason you don't hear that with the cap, is those pulses get smoothed out to a neat clean DC! Brilliant job Vince =D
Thank you Chris 👍😎
Brings back my childhood memories, my dad used to have something similar and I used to mess around with the SW band and would get those bleeps and blobs, I used to think I’ve connected to aliens, I even used to get analog cross phone lines back in the days.
"Mitropa" was a historical company that operated dining and sleeping car services on trains in Central Europe. The name "Mitropa" is an abbreviation of "Mitteleuropäische Schlafwagengesellschaft," which translates to "Central European Sleeping Car Company" in English.
Founded in 1916, Mitropa was originally a joint venture between various national railway companies in Germany, Austria, and Hungary. It provided high-quality dining and sleeping accommodations for passengers traveling on long-distance trains throughout Central Europe.
Mitropa became well-known for its elegant dining cars, which offered fine cuisine and attentive service to passengers. It also operated sleeping cars with comfortable berths for overnight travel.
The company continued to operate throughout much of the 20th century, but it declined in the latter half of the century due to changes in travel habits and the decline of rail travel in favor of other modes of transportation. Mitropa ceased operations in the 1990s.
Today, "Mitropa" is primarily remembered as a symbol of the golden age of rail travel in Central Europe and is sometimes referenced in literature, film, and popular culture.
Great video Vince, personally I prefer the long videos
Hi I haven't looked far on the comments..Just wanted to let you know that The BIG Capacitor that you dismantled Was full of Cfc So be careful Pal Bin them at the local Recycling centre...Nasty stuff that even when dry 😢
I used to play a lot with early Hi-Fi and Radio sets. I would have changed all the Caps as a matter of course on old equipment. I even have a City and guilds Certificate for repairing them. I used to have a Lancaster Bomber Transmitter/receiver and lent it to my Uncle, who wrecked it by putting incorrect valves in it. It had 700volt circuits. I have a Quad 44 to overhaul sometime.
I think we should go back to school old 80s Electronics engineering studies
Well done first time fix...you need to tell jim Lindas in Canada how its done..he would have found that last and took 10 episodes to figure it out...and he has all the tech to do it lol..and dont worry how long it takes you can still make it one vidio with editing..tell jim that too lmao😂
Your videos are among the ones that can never be too long. Like a great book, the longer the better. Those with less interest can fast forward.
It seems My Mate VINCE has stumbled across the robot overlords communication wavelength.
That is a gorgeous piece of equipment. Things back then were made so well, compared to the cheap rubbish they mass produce today. As an example, one word - BUSH! I have an old clock radio/cassette made by (I think) Wharfedale, that I got for Xmas back in the late 70s. Still worked like new when I last switched it on a year or two ago. Anyway, great fix Vince and an excellent revived item from yesteryear.
Sinus is the manufacturer of the speakers
Short wave was the ham radio users doing morse code. Nice bit of work Vince 👍👍👍👍👍 ps it would be nice to see you fixing a ham radio.
I love long videos 🔥
It kinda look like a radio we had back in the days.
/edit
The included schematics are awesome. Guess it would look a great framed on a wall.
In the states we call that insulation: Rotten Cotton!! I remember working with that when I was an apprentice electrician and had to fill the void where we penetrated for pipes and wires!! That crap itched like crazy!!!
That really is a stunner and I love the old plug! Real solid wood and amazing speakers! Great fix mate!
No not real wood, laminate covered chipboard just like the kitchen worksurfaces of the era.
many people never understand that a couple of whacks are absolutely necesary for repairs!!
I hope I can find a receiver some day that compares JUST A LITTLE to that one!
Love these vids , always make me feel a little sad technology has left this amazing stuff behind 😢 Boss vid Vince .. hope you waltzed abit to that outro 😁
I am almost certain the corrosion on the fuse folder was caused by electrolyte leaking from the capacitor directly above it. That cap looked very compromised. I'd at least be replacing that cap too!
Hi, found this on a b/o forum ''EKS is short for EKSTRA. It's merely an output for an extra speaker that you could put in for example. the kitchen or bathroom where stereo wasn't quite as important a feature.''.
A woodworking trick my dad used to do, get a damp rag and heat it up with an cloths iron. If I remember correctly its the side that bows in you want to heat. Theb put something heavy on it for a couple hours. Youd have to take the box apart though.
I recognise that hum and I notice you also still have it when out of tune on AM and LW a little which is probably mains interference you're tuning jnto.Sounds exactly the same frequency as the hum at the start of the video. Pretty sure that's 50hz mains hum. But why is it at 200hz? If you think about it 50hz is a very low frequency (thats deep bass) and many speakers won't reach 50hz. But even when my speakers don't support a frequency you can still hear it as a higher octave. 50hz may even play on my mobile! But what you're hearing is not 50hz. Is 200hz the minimum frequency of that speaker I wonder? Be interesting to see what frequency the app thinks the sound is at when you find that out of tune hum.
Thank you Paul, I suppose it being a multiple of 50Hz does suggest it is mains hum 👍👍👍
First - fix the hum problem before disassembly of the whole unit, which you already did! Replace the main power supply capacitor - it should be very dry by now. Radio being old, I would replace the 4 diodes in the bridge rectifier circuit. If the hum goes away, then the power supply is OK. If not, then there is a open ground - either in the AC power cord or on the circuit board. Good luck!!
Now you know what that "rubbery piece" is on the capacitor, it is indeed a vent. I dealt with machines designed around the time of this radio (early 60's, WAY bigger caps tho, motor start caps) nearly identical design tho on the cap. I was screaming at ya to change it once I saw all that mess near the vent initially lol. Those big caps make a nice "boom" when they short and explode, in a nice metal wireway tho on the machines I worked with still a mess to clean but good design for safety. Thankfully I only had one go BOOM in nearly 15 years. I figured you'd change it straight off knowing your (and MOST ppls) history with old bad capacitors
Great job mate. The Rolls Royce is next video now yeah????????
hum is most likely filter capacitor or some capacitors just a guess before i watch the repair
on the speaker it says Swedish speaker factory the brand is Sinus
Sine wave in Swedish is called Sinusvåg i guess that's were they got their brand name
btw instead of the app you could have used your oscilloscope on the speaker outputs i would trust that more than the app, but thats just me
Cheers Karthor 👍
Mitropa was a catering company best known for having managed sleeping and dining cars of different German railways for most of the 20th century. Maybe there was an extra radio station for trains.
With a full-wave rectifier you will see 100Hz not 50Hz. as full-wave rectification basically doubles the frequency. 200Hz being the 2nd harmonic of 100Hz.
EKS is a shortening for EKSTRA an output for extra speakers in say the kitchen
Thank you 👍
37:46 In case no-one else has mentioned it: If you plug the speakers in one way, it turns the internal speakers off, otherwise it keeps the internal speakers going as well as the external ones.
46:02 You could have connected the bench power supply to the capacitor (without turning the AC power on) to power the unit, and you would have found out that the hum was gone, i.e. it was coming from the mains AC. Something to keep in mind for the future perhaps.
Great video! Thanks for posting.
Thanks Jac 👍
I thought AC capacitors block DC current?
@@rogierius yes (more or less). The transformer changes the voltage, then diodes make sure the voltage is always positive, and then the filter capacitor is supposed to stabilize the voltage because when it comes straight from the diodes, there is still a lot of "swing" in it. When the filter capacitor isn't working, you hear it as hum. You could say the capacitor filters out the hum by shorting it to ground and doesn't let any DC current through to ground.
My suggestion was to clamp a bench power supply onto the failed capacitor, so basically to inject DC into the circuit. The failed capacitor still doesn't short out the DC voltage (now from the bench supply) but because there's no hum to begin with, there's none to filter out either (which the capacitor couldn't do because it had failed). So the system would have been hum-free, proving that the hum was coming from the power supply and nowhere else. If there would have been another problem, for example hum coming from an input, the hum would still be there.
Well done vince❤
wow... that's a 60's amp?! I had one of them when i was a kid that someone left behind when they moved house and we moved in. Sounded great in the 80's but didn't know it had value and abused that thing.
Hi Vince From Brisbane Australia, i would like to know if you would do a video on your setup please as im keen to get some gear as im starting out and wanting to learn myself, im a retired Soldier looking to get some new skills and i have been binge watching your videos an i am very keen to do this myself, keep up the great work your mate shane from down under
I think stamped in to the card in the radio was the manufacture date of 1962? Also you should tune in a known FM station frequency, and if it is off, then you can slide the dial pointer on the cord to the correct spot… awesome repair anyway
That "r2d2" sound could be a remote weather system, air control, satellite or something of that nature.
I'm watching a radio repair and it was just announced Steve Wright has passed away at 69.
Mr Carlson's Lab would tune the hell out of all those tuning cores!
200hz hum is because of the harmonic frequencies of 100hz. A rectified 50hz creates 100hz waveform before the large smoothing cap, which acts like a reservoir and smooths it to flat, clean dc voltage. Edit... The ten or so wires going to the negative of the capacitor are the grounds for the various different circuits within the unit. This is known as "Single Point Grounding" and is preferable to having many ground points either to a chassis or on the circuit board as it eliminates variation in potential between the grounds.
Awesome fix Vince! It’s kids worrying that a bit of paper is placed inside. Wouldn’t the components not get hot?
Looks awesome too.
Great repair.
I would have re-stuffed the old cap to be honest, kept the originality and no messing with bending brackets. As you know, most modern caps will sit comfortably in old caps due to their reduced size. I normally go that route even with the old waxys.
Of what lossible dangers should I be aware when doing that?
@Mymatevince you should try and post those schematics online could be handy for someone else and they looked like new, also I wonder could you have mounted the new capacitor inside the older large one ? its just those big ones look so right for an item of this age :)
You found aliens @1:07:20 lolol , i have grundig tube radio from 1959 that still works, loved the video!
I was thinking the same, lol. Sounds like the sound from Independence Day.
You need a signal tracer. That would help you isolate the noisy component.
That was CW (Morse code) you were hearing on shortwave - possibly Ham radio operators.
Finally, a capacitor that won't ping off when you try to measure it. LOL
😂 Hahaha, that one could knock out someone if it ever did ping
I'm not sure why the App was showing 200hz as I regard it as 100Hz (there is a youtube vid of '200Hz' to compare the noise with). The 100hz is caused by the 50hz mains sine wave being rectified into two half wave DC before the capacitor smooths it level (ish). Great restoration project, really enjoyed watching it .😊
It was possibly because the speaker which was connected to the unit couldn't resolve 100 hz, very well so the acoustically coupled device was picking up the second harmonic from the speakers at 200hz. Speaker devices will often frequency double in this way when they cannot reproduce the fundamental tone. Of course the bridge rectifier having inverted each alternate half cycle of the 50 hz incoming sine wave, with no working smoothing/reservior capacitor will also create a more composite (none sinusoidal) signal therefore having higher frequency harmonics, including the second (200hz) harmonic which would also be directly audible through the speaker due to its real presence. I would also expect to see a 100hz component on a scope etc., directly connected to the speaker output(s) on the receiver as well though.
@@shaunhw yep agreed. On the spectral display on the bottom of the phone there was also a clear line at 100 hertz.
Mitropa might be Mittel Europa (Central Europe), because I see cities in the same line named as "Praha", "Firenze" and, "Wien" being respectively, Praga, Florence and Vienna. The beeps you heard could be Morse code or any other type of communication in the SW range. Decades ago the Soviet Union had an array of ballistic missiles detectors dubbed as Duga (woodpecker) which made knocking sounds that disrupted SW broadcasting. The last operational site, called Duga-3, was decommissioned a while ago (around 1989).
Open the old cap?!!! you’re a saint Vince! You know what we want;)
I was told, to drain any capacitors of electricity, press the power on & off a few times with it unplugged from the mains to discharge the capacitors.
The Spectroid app is pretty awesome, thankyou for telling me what tools to use😊 is it considered an electromagnetic interference tool(EMI)?
I’m sure someone else has already pointed out the FM tuner needle travels in the opposite direction to the direction you’re turning the tuner knob
love the video but why are you not using the wiring diagram supplied to help diagnose how the radio works. I would, but thats because i'm electronics engineer.
good fix. Quality stuff. Can find out what that signal is by asking google 'what is at xxxxx LW etc'
Vince, have a look at using steam to repair "bruises" (dents) in wood. I have had quite a bit of success using a wet tea towel and a dry iron (not using iron steam).
I don't think it'll fix the corner but may tidy up the mark on the front. Take your gentle little hammer 🙂 to a piece of scrap to try it out.