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.
@@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.
@@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"!?
@@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.
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.
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.
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.
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.
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
I have a Beomaster 8000 and a Beomaster 900 in my office. The 8000 needs maintainance and has not been on for (?) 2 years now. The 900 is what I listen to. It is not as good as the 8000 when both are in good shape. The sound of the internal speakers simply cannot be crisp. If I want that, I have to add some external speakers to the setup. But I probably never will. I love the too warm sound coming out of it. It is on the mantle, doing what it does best. It brings me the news and my favorite radio shows. It relaxes me with a blanket of sound that sounds anything but harsh. Love this video. If the 900 ever starts humming everything will be replaced, but I will know where to start. Cheers!
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....!!
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.
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.
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.
.....The Ali tubes with screws sticking out are 'beehive' trimmer capacitors..They are for alignment, don't twiddle willy-nilly!! Feeling my age!!!! :-)
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.
@@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.
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 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.
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.
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.
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!
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!!
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.
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.
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.
I repaired one of those dial movements with a piece of fishing braid. The oxidisation inside is more than likely because it was used in a Kitchen with steamy atmosphere.
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.
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
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.
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.
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.
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 🌞
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.
Heay Vince, love your channel. How does anyone learn without trying stuff. Our civilisation would never have progressed without someone like you trying something out. Plenty of people in history have started on something without having done something before. I think you say it as it is. Please don’t try this but I have spent my life until my now 55 years trying everything. As long as you are sensible and take the appropriate precautions then give it a go. I fixed last weekend a blocked overflow, dodgy dishwasher door, blocked kitchen sink and a leak in the downstairs toilet. Next week is up a ladder cutting down ivy that;s been up for 50 years… All the best AB…
Such a fantastic video. For a video that was over an hour long, it felt like it was ten minutes. Watching you approach a fix always brings a lot of excitement.
Super fix Vince - It was another B&O fix from way back that found me your channel. Vintage B&O is a real challenge and I don't have your level of 'Fix' skill for these. An old thing of beauty is working again - Thanks Vince 🤓
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.
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.
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.
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.
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
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.
you can put the speaker connector in both way means that you can revese the polariy, if speakers are not connected the same polarity in connector, if you connect speaker signal opposit the other specailly you will hear it on the base that it cuts out, so turn the connector is simpler than rewire to switch polarity on 1 side.
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!
That radio brings me back to the beginning of the seventies. My first radio. Living in Denmark I of course had a B&O. There were 3 types. The was one you have. There was one with only one speaker and without any. As the radio had no stereo when reiceiving radio signal you could by this as an extra option. I modified it with a knob in the front so I could change the balance. The terminals for the speakers at the back was made so you could have have the internal speakers on or of by rotating the knob 180 degreese.
The one in the video does receive FM stereo. The stereo decoder was sold as an upgrade in Denmark, as FM stereo wasn't around in Denmark when the radio was new.
Amazing repair and like the model. Would have this in my lounge for everyday use. I use a radio everyday. Very surprised that it didn’t have a backlight too. Thank you
I thought it wasn't backlit even though I seen the lamps. However when I turned the lights off I could see the backlight then. If you skip to the end of the vid I show a little clip of it at night 👍👍👍Looks nice
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 😢
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!
200hz is the second harmonic of 50hz. Also as others have said, remember that the bridge rectifier effectively turns a 50hz sin wave and yields 100hz. 200hz is obviously the first harmonic of 100hz. The capacitors would normally smooth this out, so it does suggest there are one or more cap failures.
Others have made very good points about the capabilities of speakers and microphones to pick up very low frequencies. It's also possible the resonant frequency of the speakers themselves is close to 200hz, causing the 200hz peak to appear higher than it is in reality. Connecting the speaker output to an oscilloscope would probably have shown 100hz to be the dominant frequency.
I am a bit late to the party, but I thought I'd throw this out... Those cans with the screw things in them are the RF and IF amplifier tuning inductors. If you don't know how all that old-fashioned radio stuff works, DO NOT mess with them! I love your fixing anything videos. Thanks for presenting these.
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
Nice vid Vince, thanks. Electrolytics are made to last a maximum of 20 years, so it might be worth changing all the caps. 200Hz is probably a harmonic of the 50Hz, after the bridge/smoothing rectification cap, it will be 100Hz.
... 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 }
Finishing touch would be to replace the red paint on the tuning strength needle. The garbled noise on the long wave could be "single sideband" encoded.
The R2D2 is CW (Continues Wave - morse code) on one of the amateur radio bands 🙂 The small metal components with a screw at the top is adjustable capacitors for tuning of high frequency/radio circuits. Thanks for the video - from Denmark, the contry of Bang & Olufsen (B&O) 🙂
Nice radio, Vince :) I am restoring a Silver ST858 boombox. The biggest boombox I ever had. I like these old radios, because they are built to last forever. The speaker connectors on your radio have 3 holes because they let you choose to leave the internals on. If you plug them in the other way around, they will turn the internal speakers off.
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.
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.
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.
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.
Whenever I see your kitchen floor I think of my bathroom before we flooded with sea water a few years ago, had exactly the same tiles and even had the same black grout !
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.
Hi Vince one tip to sort out the dent in the wooden casing is poor boiling water on the dent. This bring the dent out. You may have to sand it back slightly
Even in the 80's we would say "Blue Electrolytic? Replace it!" Philip's Caps (blue) were reknowned for failure after even a couple of years. Oh - don't forget to zero your ESR Meter before using it!
Hi Vince, what a good result. I also thought it was the capacitors. The rest of the fixes is also nicely done. Oh no, the video is not too long, I could watch it for hours. Greetings and keep up the good work!
I'm Danish. The "K" stands for Short. B means Band, LB = Long Wave, MB = Medium Wave etc. The EKS probably allows for a Mono stream to a suplimentary speaker, hence the ballance pot beside it. B&O used DIN connectors, the external speakers sockets may allow for a connection to bass & treble drivers. Have you considered an FM antenna in the loft. I had one on my previous house and sterio reception was MUCH improved Radio three was almost CD quality.
1. The reversible speaker connectors contains a switch that can disconnect the built in speakers. If the round pin of the speaker plug is in the small hole, the external speakers are connected in parallel to the built in ones. If the round pin is in the larger hole, the built in speakers are disconnected. 2. You can replace the scale pointer cord with Fly Fishing Line. 3. You can easily make a simple dipole antenna for better FM reception. Look up "FM dipole antenna" for hints how to make one.
The Bridge rectifier is a Selenium type, just on the cusp of turning over to solid state rectifier diodes. Sometimes they were wired in a half bridge configuration but were renowned for being noisy anyway. One reason why a bloody great capacitor was used, in the old valve radios with a valve rectifier they used to hum @ about 100-200 hz until the tube warmed up.
I have a 70’s Clock Radio, that had a back up Battery for the Clock and Audible Alarm. In the Early 90’s the Battery gave up. I took it apart, found a Double A Battery Soldered in. UnSoldered it Soldered some thin wires on those points and ran them under the Radio. Purchased a Single Battery Holder, there was just enough room to mount it underneath. Still working to this day, Battery Recharges off the Radios Circuit. About every 10 to 15 years, I easily replace the rechargeable Battery.
Wow great work! Seems to very often be the capacitors in these old things. What you could have done to make it look original would be to hide the new cap inside the hull of the gutted original capacitor.
+EKS is for another mono output to extend into another room, the 2 pin DON (speaker) socket will be fir a speaker connection that locks into place. A speaker plug in will possibly work because the negative side might be touching to ground of the casing where the plug locks into place.. Those old string connections always baffled me as a kid when I used to pull everything apart for no reason other than curiosity....
![[LIVE] : ONE ลุมพินี 88 | คู่เอก "ป้อมเพชร vs อัสลามจอน"](http://i.ytimg.com/vi/1ZqTVVbMgbo/mqdefault.jpg)
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.
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.
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.
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.
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.
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.
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.
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.
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 👍😎
I have a Beomaster 8000 and a Beomaster 900 in my office. The 8000 needs maintainance and has not been on for (?) 2 years now. The 900 is what I listen to. It is not as good as the 8000 when both are in good shape. The sound of the internal speakers simply cannot be crisp. If I want that, I have to add some external speakers to the setup. But I probably never will. I love the too warm sound coming out of it. It is on the mantle, doing what it does best. It brings me the news and my favorite radio shows. It relaxes me with a blanket of sound that sounds anything but harsh.
Love this video. If the 900 ever starts humming everything will be replaced, but I will know where to start. Cheers!
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
Love this unit - what a beauty - and well done on the fix!
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 ❤
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.
.....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👍
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.
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
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.
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 👍👍👍
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!
I think you have the volume and tuning knob swapped. Super fun video, and great project.
finding a schematic diagram inside device was 10/10👌
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!!
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.
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.
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
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.
Ive enjoyed this over 2 nights ..lovely machine ..
I repaired one of those dial movements with a piece of fishing braid. The oxidisation inside is more than likely because it was used in a Kitchen with steamy atmosphere.
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.
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
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.
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.
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!
It actually sounds a lot better than I thought it would. B&O for you, I guess. Even 60 years old. Thanks for the video, mate!
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.
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.
Heay Vince, love your channel. How does anyone learn without trying stuff. Our civilisation would never have progressed without someone like you trying something out. Plenty of people in history have started on something without having done something before. I think you say it as it is. Please don’t try this but I have spent my life until my now 55 years trying everything. As long as you are sensible and take the appropriate precautions then give it a go. I fixed last weekend a blocked overflow, dodgy dishwasher door, blocked kitchen sink and a leak in the downstairs toilet. Next week is up a ladder cutting down ivy that;s been up for 50 years… All the best AB…
Such a fantastic video. For a video that was over an hour long, it felt like it was ten minutes. Watching you approach a fix always brings a lot of excitement.
Oh ! That outro music was amazing ! So glad all in all it was an easy fix. Has wonderful rich sound too !
I wouldn't expect it to sound great with those speakers but I absolutely love the look of it!
Super fix Vince - It was another B&O fix from way back that found me your channel. Vintage B&O is a real challenge and I don't have your level of 'Fix' skill for these. An old thing of beauty is working again - Thanks Vince 🤓
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.
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.
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 😅🤣
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.
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👍
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.
you can put the speaker connector in both way means that you can revese the polariy, if speakers are not connected the same polarity in connector, if you connect speaker signal opposit the other specailly you will hear it on the base that it cuts out, so turn the connector is simpler than rewire to switch polarity on 1 side.
amazing work vince! Also it's crazy how much technology can move in 60 years
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.
Cool, he's showing the whole truth! No edition, he discovers and show. I love it!
That radio brings me back to the beginning of the seventies. My first radio. Living in Denmark I of course had a B&O. There were 3 types. The was one you have. There was one with only one speaker and without any. As the radio had no stereo when reiceiving radio signal you could by this as an extra option. I modified it with a knob in the front so I could change the balance. The terminals for the speakers at the back was made so you could have have the internal speakers on or of by rotating the knob 180 degreese.
The one in the video does receive FM stereo. The stereo decoder was sold as an upgrade in Denmark, as FM stereo wasn't around in Denmark when the radio was new.
Amazing repair and like the model. Would have this in my lounge for everyday use. I use a radio everyday.
Very surprised that it didn’t have a backlight too.
Thank you
I thought it wasn't backlit even though I seen the lamps. However when I turned the lights off I could see the backlight then. If you skip to the end of the vid I show a little clip of it at night 👍👍👍Looks nice
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 😢
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!
200hz is the second harmonic of 50hz. Also as others have said, remember that the bridge rectifier effectively turns a 50hz sin wave and yields 100hz. 200hz is obviously the first harmonic of 100hz. The capacitors would normally smooth this out, so it does suggest there are one or more cap failures.
Others have made very good points about the capabilities of speakers and microphones to pick up very low frequencies. It's also possible the resonant frequency of the speakers themselves is close to 200hz, causing the 200hz peak to appear higher than it is in reality. Connecting the speaker output to an oscilloscope would probably have shown 100hz to be the dominant frequency.
I am a bit late to the party, but I thought I'd throw this out... Those cans with the screw things in them are the RF and IF amplifier tuning inductors. If you don't know how all that old-fashioned radio stuff works, DO NOT mess with them! I love your fixing anything videos. Thanks for presenting these.
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
Nice vid Vince, thanks. Electrolytics are made to last a maximum of 20 years, so it might be worth changing all the caps. 200Hz is probably a harmonic of the 50Hz, after the bridge/smoothing rectification cap, it will be 100Hz.
Apologies if someone has said this already but I think you have strung the FM tuning backwards as it goes the other way to the AM one.
Some B&O gear has extremely unintuitive controls, but I think you are correct. It just feels TOO weird to be the opposite between FM and AM.
... 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!!!!
Great job Vince! I love restoring vintage audio.
Seeing these old beauties come back to life is so satisfying
Finishing touch would be to replace the red paint on the tuning strength needle. The garbled noise on the long wave could be "single sideband" encoded.
The R2D2 is CW (Continues Wave - morse code) on one of the amateur radio bands 🙂
The small metal components with a screw at the top is adjustable capacitors for tuning of high frequency/radio circuits.
Thanks for the video - from Denmark, the contry of Bang & Olufsen (B&O) 🙂
Nice radio, Vince :)
I am restoring a Silver ST858 boombox. The biggest boombox I ever had. I like these old radios, because they are built to last forever.
The speaker connectors on your radio have 3 holes because they let you choose to leave the internals on. If you plug them in the other way around, they will turn the internal speakers off.
I used to have a 1941 naval comms receiver. Amazing and beautifully built
Wow, what a great idea. I need to experiment with that with my external speakers. Thank you!!!!!
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.
Astonishing build quality, and considering its age it looks better than some of the new stuff you repair 😮
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.
thats very nice...compared to modern audio equipments that breakdown in 6 months...
these things are really built to last...nice one vince..
Thank you for showing it light up in the dark. A beaut!
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.
Great fix and very nice futuistic looking device for the time. Wierdly, the F.M. frequency goes up when tuning to the left. Have fun.
I would definitely get the cabinet remade and you'd have a beautiful piece of kit.
I enjoyed your glee at finding it working.
Brilliant I love seeing old things brought back to life ❤
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.
Whenever I see your kitchen floor I think of my bathroom before we flooded with sea water a few years ago, had exactly the same tiles and even had the same black grout !
😂👍
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.
you know what else is a beauty? you, Vince!
love you and your content bro, been watching you for AGES!
love the old school motherboards or daughter boards you could easy rebuild that case and make it perfect great upload ...............
Great to see it all working again, it's a lovely thing. If I had space for it and the missus wouldn't get cross, I'd have that!
Hi Vince one tip to sort out the dent in the wooden casing is poor boiling water on the dent. This bring the dent out. You may have to sand it back slightly
What a well made radio and a great fix.
Even in the 80's we would say "Blue Electrolytic? Replace it!" Philip's Caps (blue) were reknowned for failure after even a couple of years. Oh - don't forget to zero your ESR Meter before using it!
Can a decent multimeter do what an ESR does?
RIP Steve Wright, Radio wont be the same...
Hi Vince, what a good result. I also thought it was the capacitors. The rest of the fixes is also nicely done. Oh no, the video is not too long, I could watch it for hours. Greetings and keep up the good work!
Remember those knobs and pushbuttons in the stereo cabinet. It also contained a record player and tv. What a great piece of danish engineering 😊
I'm Danish. The "K" stands for Short. B means Band, LB = Long Wave, MB = Medium Wave etc. The EKS probably allows for a Mono stream to a suplimentary speaker, hence the ballance pot beside it. B&O used DIN connectors, the external speakers sockets may allow for a connection to bass & treble drivers. Have you considered an FM antenna in the loft. I had one on my previous house and sterio reception was MUCH improved Radio three was almost CD quality.
1. The reversible speaker connectors contains a switch that can disconnect the built in speakers. If the round pin of the speaker plug is in the small hole, the external speakers are connected in parallel to the built in ones. If the round pin is in the larger hole, the built in speakers are disconnected.
2. You can replace the scale pointer cord with Fly Fishing Line.
3. You can easily make a simple dipole antenna for better FM reception. Look up "FM dipole antenna" for hints how to make one.
Some tips regarding oscilloscope usage: Use AC coupling to see the AC component - an use a longer time base to better see the whole ripple.
Waxed tooth floss string is tough stuff and might work at a pinch.
It's been a while since some good ol' Bangs and Olufsens have on the channel. Looking forward to it.
It has...BUT I'm working on another B&O beauty right now, hopefully it will be released in a week.
@@Mymatevince More B&Os? Send in the B&Os.
if i remember correctly its from the 90s? a beocenter @@brutlern
Great video. It would be nice to add a note containing details and date of the repair to the brown envelope.
The Bridge rectifier is a Selenium type, just on the cusp of turning over to solid state rectifier diodes. Sometimes they were wired in a half bridge configuration but were renowned for being noisy anyway. One reason why a bloody great capacitor was used, in the old valve radios with a valve rectifier they used to hum @ about 100-200 hz until the tube warmed up.
That was a lovely fix! Beautiful piece of vintage electronics.
I have a 70’s Clock Radio, that had a back up Battery for the Clock and Audible Alarm. In the Early 90’s the Battery gave up. I took it apart, found a Double A Battery Soldered in. UnSoldered it Soldered some thin wires on those points and ran them under the Radio. Purchased a Single Battery Holder, there was just enough room to mount it underneath. Still working to this day, Battery Recharges off the Radios Circuit. About every 10 to 15 years, I easily replace the rechargeable Battery.
Wow great work! Seems to very often be the capacitors in these old things. What you could have done to make it look original would be to hide the new cap inside the hull of the gutted original capacitor.
+EKS is for another mono output to extend into another room, the 2 pin DON (speaker) socket will be fir a speaker connection that locks into place. A speaker plug in will possibly work because the negative side might be touching to ground of the casing where the plug locks into place..
Those old string connections always baffled me as a kid when I used to pull everything apart for no reason other than curiosity....
That should read 2 pin DIN not DON 😊
For the dented wood, you can try covering the dent with a damp cloth running a soldering iron over it. Basically steam it back into shape.