1957 Telefunken Opus 7 Repair & Bluetooth Mod

[Music] I'm quite excited to get this one on the bench it's been waiting a while it's a tunen Opa 7 it's a big old radio from the ' 50s and it's absolutely beautiful it looks very Grand I think you have to be quite Posh to own this it's quite a surprised to see so many controls in the 50s wow running through the buttons we turntable inut a tape player input this is some sort of special function I think that's a am this is a filter or some sort of bandwidth control I'm not sure how it works got medium wave short wave and FM buttons at the front of the voice controls it's like an early EQ system there's dual tuning knobs here we got a small knob that adjusts the top scales and the larger knob is for the FM scale at the bottom treble control will just be a potentiometer I think and it's the same deal for the base control another pot and the Dual control knobs on the left left this is for steering the ferite antenna I've seen that before that's pretty nice and this I think is the volume but my God it's stiff yeah oh certainly needs attention and the rear this is also really nicely labeled I like these diagrams these are brilliant quite clearly explains what sort of antennas go wear and a very good hint of how to ground it here's input of the record player tape player and I think this is an additional speaker output that's pretty cool didn't know it did that made in West Germany I think it was Hanover the home of Volkswagen and Continental Tires pretty easy to take the back off these you just slide these across and we're in wow this thing is full of loud speakers I reckon it's pretty loud there's our AJ chassis not too Dusty either this is the Main's transformat I don't know if it's Rusty or painted no I think it's paint very good these three valves make the power amplifier section the el84s in push pull configuration I reckon and this will be the output Transformer presum well especially as all these wires go to the speakers oh hello what's this is a ferite rod dangling oh shouldn't you be in there H well this will be the steerable antenna assembly and the ferite rod appears to fell out and I guess the glue's dried out after 66 years fortunately there's only one coil on it so there's one wire come off so we should be able to work out with that goes and in the bottom of the case is a lovely hold we can get to most of the electronics oh what's this there's rather onti cluster of ground connections there I'm assuming it's broke off there H someone's had this apart then there's only four or five screws get the chass out so just going to undo them well the shot is out the cabinet and there's plenty of cables for the speakers but my bench isn't deep enough so I'm going to unsolder these for now hopefully these are just lying against the pins rather than wrap around them we'll find out oh yes good news they come off nicely this radio has been sent in for overhaul so a little bit of repair and a little bit of replacing Parts just to make them new and safe which immediately means ing things like this which is just visually obvious what's G on and then we'll be replacing some dodgy components like this antique electrolytic cap which I bet doesn't work and anything that looks visually distressed like this cap that's got a split in the end of it hope you don't have to replace any of the valves cuz they get a bit expensive and they're not always that readily available but first impressions they're all sort of silvered at the top so the getter still intact you can tell when the case has lost his vacuum cuz he's turned white and start off taking the shield off the ferite rod holder just slacking this screw off think I can turn it [Music] around now I need to rewind this a little bit put the turns back on as neatly as possible work out where the end was there I reckon put a bit of CA glue on there just to hold it just going to put a little touch of epoxy on here and same over here let's locate the ferite rod in the hold there that should stop it Popp out again let's put a bit of epoxy over the coil just to secure it let's give that little wiggle cuz I'm not sure if that wire is supposed to be touching against the F out ride because there's insulation under it here now I can reattach this broken end but first I'm going to feed it through this insulation just wrap it around if I can I can put this cover back over there just sort of twists in place the antenna's FED into this RF oscillator come mixer and that signal then passes through these filter sections through this demodulator then through the power amplifier which is this pair of el84s and their output goes to this Transformer back to the speakers quite often these old receivers more or less work but I want to see how it sounds it connect my speaker loads onto this let's see how it likes on power trying to adjust the trigger on this there we go well it's humming a lot which is a good thing means the amplifier's working don't know if I can tune it in does am work not much happening on medium wave this home sounds power supply related to me just on Sumit quite like the cassette tape or ton band Yes it's made no difference I don't think anything's happening with the Magic Eye display either it's a shame I don't think am's working at all let's put a local channel on at 1 MHz that should be around [Music] here there nothing doing at all tell you what else the volume knobs doing absolutely nothing oh it's tight oh God it goes one way and not the other some it wrong there try short wave say 5 [Music] MHz nothing wonder why it can manage FM but not am should be simple to demodulate that's a bit weird try the aerial tuner that makes no difference but I'm interested in what that switch does it looks somewhat [Music] tarnished this radio definitely benefit from the Caps being replaced they're very old and there's a lot of home it's probably that but I don't think caps are responsible for the AM radio not working hm got the schematics here for the radio and it's very apparent there are switch contacts everywhere throughout the circuit and I'm pretty sure switch contacts are going to be dodgy on here this is the diagram of the switch Matrix and I've just colored them in so I can just see where they're distributed on the circuit diagram VHF oscillator mix is working generating 10.7 MHz we know this cuz we've heard the FM radio and I suspect that these switches here offer duning this oscillator down to a lowest frequency of 460 khz and these are for selection of the different bands as well so switches everywhere could be a lot of trouble just put the r on its back so I can have a good look inside and this is a switch Matrix this hold the assembly here and a lot of the components are mounted directly on it including some little loose coils it's entirely possible if a little wies broken off in here That Could Just Kill the am reception dead so I need to check all of these this could be quite involved I thought this was a capacitor at first but it's not they got four wires and I couldn't see enough markings but it's a silly rectifier you don't see those now I might have diagnosed this already turns out this wire is loose it's not connected to anything and I have no idea where that's come from and it sits on top of the short one switch there's a good chance this is what it is that said on this diagram here I would say that is sp 12/3 and there it is right there right in the midst of the circus I was suspicious of wow of course there's two windings on this so there's a thick one and a thin one so this thick one here is easy to spot goes to this trimmer here this is a capacitor labeled F there's a preset trimmer F there we go so the thick wire is here so this thin wire is here so it's either broken off pin a of this valve or tube if you're American or it's broken off this little Network here there's a few things attached here see which one's easiest to spot I'd say that's quite easy to spot 33k resistor going to the FM switch and that's here so it's got to go on this leg here okay following These Fine wires we got this one is attached it's attached to part of this switch which I think isn't actually connected to anything else it seems to be no other contacts so I reckon that goes to the uh plate to that valve this loose wire here just floating around must go here which is where the end of that resistor is it helps that the wire's the right length as well adds more sort of plausibility to this Theory this is a very fine wire I can barely focus on it but I'm just going to see if I can put the iron against it see if it will melt the insulation or not looks like it has see if I can tin this little cluster let's touch it on there that's it that's going to be worth trying it again now isn't [Laughter] it and um the other guy who 80 something you're not keeping that P in the F in traditional life that's powerful isn't it let see if it picked up that one MHz tone I've got yeah it does but it's not far off at all I'm really pleased with this see what it does on Long wave ping control is not doing anything so check the FM calibrations pick a frequency that's nice on the display like 93 MHz that's to knock the am modulation off stitching FM on [Laughter] [Applause] okay it's not entirely broken now so it's just a service we fetch the glass panel off so I don't damage it take these knobs off first though this one doesn't appear to fit it's too big plus small one all straight in hopefully this is all I need to undo to get this off so this is the volume knob shaft and that's absolutely solid this ain't moving at all I see a long shaft in quite a long sleeve and I reckon that's just seized up bit of Lube's needed I think and Brute Force well try a little bit of oil in there look it's pointing down so it might run in put some pliers on it and see if I can get it to move oh just about not very far mind you now it's tur a little bit I'm going put the knob back [Music] on another little trick I've thought of is put the solding lon just against the housing there just to transfer a little bit of heat oh that's getting a lot looser now oh it's definitely down that end that's where it's stuck oh that's freed right off now it's hard to tell if the tone control is working or not with all that 50 HZ hum on it it's a nice open frame design it's going to give shot of deoxit it's probably all it needs same with this one although I am rather drawn to the state of these switches this one's absolutely bent out of all proportion that's never going to work you see how tarnished they are there's some heavy black deposits on here that's not supposed to be on there at all this will be a good test to see how good this stuff really is can it shift that give a bit of agitation with a brush is it doing anything probably nice substitute for a good thick brush with some iceo prle alcohol well to be honest I've never found anything as effective as the fiberglass pencil although it's a vile device giv out loads of sharp fibers It's very effective I need to find some way of un mangling this not quite sure how it doesn't want to sit straight think if we Bend these contacts a bit out of the way allow me to pull this forwards a bit more maybe like that let push these back that they just about touch H let's check we Haven got any shorts I now no that's good and behind there nothing Engage The Switch perfect okay good this one's normally closed so this one should already be connected oh open what this side do that side's okay H just tease this back a bit not so much of the permanently bend it I can see the little contact tip there how dirty is this thing oh very black look at that how's that now still no good is that one still okay yeah think I need to bend that little tank just tease it slightly see how that works for us perfect that'll do the main switch Matrix bit lot harder to get to I think I have to put a lot of spray down there and give it a good old work out I think the contacts are on the bottom so I need to squirt it in so it goes that way and then light down this way and let it sort of sit there dip it that way for a bit and then right the way this looks a bit dirty doesn't it lot of dust Al there's a lot of the paints probably going to FL off never fully show how far to go with this [Music] stuff br that up a bit as well lovely so look at this switch how's that working so that into there it's not very good M so I'm get the fiberglass pencil in there as well just give a bit of a wash with isopr try that now perfect the most likely cause of horm is this thing here this is a dual capacitor these are the main filter caps for the whole radio so that's 250 microf caps in one can and at the bottom of the capacitor you can see these two red wires these are the two positive connections the common for the ground is actually connected straight to the chassis you can't get new double capacitors anymore so you have to make do with a pair of separate ones just need to find somewhere to put them just move the sleeves off here first so I can take these off I think that ground connection is just a big blobber solder don't get the dising tool in [Applause] [Music] there I could do a shift in this big flywheel off this shaft it's in the way really hopefully it doesn't do anything surprising when I take it off there is a spring on that shaft no dramas I can straighten these tabs I should be able to take this capacitor off let's see how bad it is so put the ground clip of this meter on the casing I measure the first one 500 narad yeah that's pretty bad let's measure the second one 544 nanar this Cap's absolutely knackered going to put this back in just for the Aesthetics to be honest I'm not going to use it but it looks pretty let's make the double capacitor I'm just going to glue a pair of standard caps together is a bit of hot milk GL well the glue guns Hot most glue this coil down if I can get it in there bit a tight squeeze just a little dab and just stick it down to hold the cap so you can put a cable tie through here if I can feed it through the other hole a sticky foam pad there just to stop the cap sort of rubbing on the chassis start the cable tight up a little bit put the caps through pull it up let's pull this ground leg over here sort of twist it around just sold those together so shorten these legs on here cuz we don't want too much exposed high voltage p I'm just going to Tin the end of these so they sold them more easily try not to melt that wire put these inting sleeves over there going to hook this wire over the ground and just sold it on I just want the shape into the wire so it just hooks into the ground point there hopefully making it very easy to solder on I think that's good to put some hot air on here to shrink that [Music] down now I can put the tuna flywheel back on some rather funky looking old electrolytic caps here this one's 100 100 micr only low voltage I'll see if it unsolder but normally they've wrapped the wire around the solder tag so you can't get it out cleanly I don't really want to undo everything else either no this one's fighting me just going to cut it off try this connection here see if it will come out there it's hooked around but I might be able to get it maybe yes there's also this two microf cap also strange looking that's got to come out as well just going to melt that again just pop this new capacitor's leg just inside it see if I can unsolder this end [Music] now this cap here looks a little little bit ropey I think it's probably okay but I'm just going to whip it out if I can get it to unhook out the sold the tags again yeah that siid out yeah you can see a mold lined there and there but in the middle yeah this is a crack that's formed yeah it needs to be placed definitely going put this in its place a much higher voltage rated as well clear I need to hold this one still that's better Al one replace this little cap here 2.2 nanofarads the end sort of split off yeah that's getting cut off as well finally this is a couping c for the base speakers it's 50 microf or roughly thereabouts it definitely affect the tone modern caps a lot smaller so it can just fit under me I also need to replace some main Flex cuz look there's a bit of insulation missing there that ain't very clever the one more goes to this switch under here bit awkward to get at and the other one's on this fuse holder I'm replacing it with some lamp cords it looks quite nice matches the original color shame to ruin the look the thing with a white cable so I'm putting the neutral onto the fuse a lot hard to put the cable back in the switch but there we go live on the switch so I'm tidy these Frayed Ends up with a little torch just get a little melt there you go now the other thing on the snagging list is this rather D magic I tube I'm going remove it it's on the clip I think oh you just about to see it there that's an uncomfortable movement that was the tubes wrapped in a paper sleeve to control which part you can actually see see if I can push the tube out of it there we go so that's the original one an old Brar branded one wow can't actually see anything wrong with it as such but yeah very very low emissions got the replacement one here I think this is a Russian version of it it's slightly bigger than the original the internals look pretty much the same certainly the front view of it but the envelopes a lot bigger a much taller valve might have trouble fitting it yeah there's no way this is going to fit in that sleeve I have to sort of undo it look it's helding together with some old tape okay so it fits like that quite easily I might need to apply some new tape on this I'm not sure that's how it goes got to persuade this to go back inside this click that's could be a bit of a challenge let's see how it works now see if that homing is gone he's on the well I'm pleased with that that's working got spoted some it isn't this tube's not doing anything look at that should be some green glow going on as I scroll [Applause] across need to do some digging something weird there and I'm immediately suspicious of this wiring because it doesn't quite match the drawings there's a wire link there and this resistor goes between pins N9 and six it shouldn't do that resistor should be going to pin seven not six and there's there's no link there's no link at all this has been configured to use a different tube it's supposed to be an em80 tube it's definitely a Magic Eye it looks like one it could be an em 85 84 H I think I need to change wiring pin one's the grid that could be it there's a wire there pin 2 should be ground so that's connected to here we'll move that over you can see pin 2 used to be solded so I'm quite confident this is what's going on this link was never supposed to be there this is pin six that shouldn't have anything on either it's that resistor and that's wire here this should be on pin seven that sold is a bit dead let's get some flux on it actually insulation on this wi is a bit knacked as well it's not great okay I'll turn this back around face the right way get it into position we'll see what it does [Applause] now well there's a green glow there but it looks to be very badly biased Wonder else they've got wrong so going from ground to pin n should be 230 Vols and it's not it's only 42 Vols that's a bit weird with the other side of this resistor which is pin seven we got 205 think the red why is the wrong way around well let's try that that looks better there about the music got into it well that's working perfectly lovely this radio is pretty much working now but the only ones we to put bluetooth in it Bluetooth is something I've done a few times on this channel so far and I love these little modules they're very simple and I've even got my own interface circuit which handles everything I need and I've even got a PC beers to L all out on dead e but I've got a new way to solder it this time I'm using solder paste in a syringe dispenser it's going to be quite quick I hope all I need to do is put a blub of this on every surface mount pad you don't need to be too accurate how you put the solder paste on it's actually a mixture of flux and powdered solder when you heat it up it'll all melt together and sort of flow into a nice little blob and it will stick to the pads where you should be it's clever stuff I start with a bigger components and the tricks not to put your hand in the paste you'd be surprised when it'll sort itself out got a little PNP transistor there there's one there one there one there a little Darlington transistor there one there that's a switch in the relay cuz you need a bit more current now on to resistors 22k there and there one there got an LED on here 10 o there another one there 47k there 22k there now if you ceramic and now some mouth DS God knows how I design these in they're terrible they roll around everywhere there's any a d there and another one there they look exactly the same so don't mix them up then the Bluetooth module itself just plops on there's various ways of heating these up you could use an oven or hot air or whatever you like but I'm using a hot plate going to clamp it down cuz a board May warp during the heating exercise let's turn it on I Learned My Apparel to let this stuff um dry out first the solder paste is very hydroscopic and absorbs a lot of water and if you don't get the water out you can have this Effect called popcorn which is really annoying throwing all your components in the air so I'm going to let this sit at 95° for a good half an hour what I'm wa for the bo to warm up I just had a look around here and found another cracked capacitor let's take that one off if I can if it's going to be awkward I'm just going to cut it out yeah look at that crack right across okay another little job to do is this plate here around where the magic eye is obviously gets a bit warm but it sort attack the paint and it's sort of shrunken cracked off there's a bit of sort of gold and black colors that's missing let's see if I can TI it up without making it look [Music] terrible the pl completely dried out it's gone a sort of light gray color now so it's to heat up I'll put the extraction on to get a bit [Music] smokey [Music] now that's Co off it's time to fit the through hole components it's best to start with the shallow stuff first which I think is this little potentiometer this one's a little 100K single turn job [Music] then it be the re relay it's only one of those been fitted cuz this is the mono version next are these little film capacitors which are used to couple the audio signal in and out of the board then we get the electrolytics these ones are for a bit of power supply smoothing and timing functions make sure get them in the right way around [Applause] finally the main filter caps we need these because this is actually fed with an AC Source from the Transformer so we need to filter all that sort of AC way format chop these legs off as well I reckon that's complete but I just need to give a little function test going set this up for a jaw Supply so I'm link those together voltage 12 Vol current will say 0.1 don't to blow anything up I need to put a link between the negative and the positive terminal positive goes here this be my negative Supply there's my ground going to put some test pins in the little sockets there they're a bit loose but it shouldn't matter put the ground in the middle and the other supplies either side doesn't matter which way around turn it on no shorts looks good the good news is Bluetooth modules alive and I've got an idol light on there that tells me that it's muted so if I play a song on it this will start flashing ID light goes out that's perfect if I stop the song Bluetooth module stops flashing then the idite should come back on in a second there we go perfect she passes the test just got to install it this p is just a piece of plywood where I just literally drill some holes in it and just Hammer these screw heads in just to make it flush I put these holes in there as cable strain relas don't really need them but I was going to use them anyway cuz well they're there it looks quite tidy when you use it for the audio signals I'm using microphone cable cuz it's got the two cores and a screen perfect and to poke the wires through there in the similar way that should just sit nicely on this piece of wood now the trick to Bluetooth modifications is knowing where to insert the signal we can see here we got the speakers and we got the power amplifier section here so clearly here around here is the input and this capacitor is exactly where to put the signal so I'm going to lift this end of this capacitor out and inject the signal in here hope it works and this is the capacitor in question and it just comes out the Dem modulator down there so I'm just going to unsolder it just tapack this blue wire onto there need to turn this red wire onto this cacor here going to put an insulator on it CU that's quite a span and I don't know what voltages are on it hold that like that tease this insulation right over it there we go the cable Shield needs to connect into ground so just going to solder it put it tin it a bit let's pick sck it up there okay I'm going to connect life F my little Transformer to the voltage selector switch cuz I don't want it operating on the wrong voltage and just connect the neutral here which is the output from the switch I have had to change this Transformer the other one was a bit bigger and it had better regulation which sounds like a good thing but they're both 9vt Transformers but I actually need a bit more than 9 volts I really didn't want plus orus 15 volts on this circuit and I was only getting plus orus 12 so I've gone back to the old ones which is a bit smaller lots of good regulation and I've got a better voltage sh we didn't film it so now a live test of the [Applause] system that's that's a TST let's try the Bluetooth yikes that sound quality is really bad what is causing that if I look at this I can see this looks almost rectified there's waveforms at the top but nothing coming down I think we got a dodgy component very dodgy is it just the Bluetooth or was it the radio as well no it's as well look at this same way for sounds very raspy three hours in three you can see the three valves on the top but the circuitry is underneath so the signal comes in here goes onto the grid of this little valve the job for this small valve is to create an inverted signal for the two power tubes be a good idea to check for Distortion here so I'm going to need another oscilloscope probably need to disconnect this coupling cap here as well where the signals going in if I can pull this back and he just solded it on I put a test signal on from the signal generator so it's a nice clean signal prob the output of this cap just to see that it's not that cap itself we see already nothing wrong with that nice and clean that's not the problem for the grid of this el84 is on pin 2 here so I need to connect to this resistor here this is the lower el84 this resistor here I'm going to connect on to there oh did you see that it's gone very uneven it's okay up to a point and then it's gone wrong just for clarity both of those waveforms should be identical but inverted they are in inverted and I would say slightly pH shifted but you can see the result of what you get here that's a very wonky sine wave I'm going to turn the power [Music] off yeah not good I think it's this one just hold to the end of it see if I can tack a modern capacitor in each place it's a tight squeeze let's put our test leads back on scope Probe on there and scope Probe on there power on so far so good oh we got much higher output much better look at that perfect no [Music] Distortion okay that's found that problem I need to TI of this W up there I can't leave it dangling like that and I probably ought to change the other one cuz I've actually put a different value capacitor in should be 2 2 nads and I've only 47 it's cuz I haven't got any but consider it an upgrade think could be is just to snip that old one out the one's bured under here this resistors in the way I I have to snit that off as well interesting the different voltages this one's 250 volts and this this one's 500 H if that's why it broke down let's see if that's fixed it she beat the light detector I've never seen anything like it I me I I always feel a bit intimidated by defitely sounds better brilli that's better no Distortion now that's I don't need that on now now my favorite part putting it all together it's got to tease this glass facia back on bit of jiggling required oh rubber Parts already dropping off going to persuade this little rubber Mount to fit in so I just bend that down get it to slot in and hopefully oh that'll do it's a little bit broken but it'll hold it same here slide that [Applause] on let's connect this Earth wire back up think it went there just put the back cover on on the a through there it's all back together and it looks stunning I want to try it while waiting for I think one of her kids to watch a film at the cinema working there is no tomorrow I aming excellent so uh these two games especially tonight we are creating lots of Chan that works perfectly too very happy well I'm very pleased how that's turned out it's working brilliantly and in the nick of time too it's been collected in morning catch you next time I think they will I think they always do

Channel: Mend It Mark

Views: 199,138

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Id: N4pNpnqbXzw

Length: 55min 57sec (3357 seconds)

Published: Thu Nov 23 2023