1942 Ducati Radiogram Repair (Part 1)

[@butcharmstrong9645]

WOW something older than me! I just turned 70 December of 2022 so this Ducati is a decade older than I am! And I'm sure it works better than me too lol

[@gminker]

Hello Mark, Those little twisted wires as you surmised are under 10pf and were used extensively in early radio and early TV chassis to peak IF tank circuits. The twisties were called gimmicks. Cheers

[@James_Bowie]

Yep.

[@antronargaiv3283]

Allows you to tune the capacitance value as needed to resonate

[@McTroyd]

8:02 @Mr Carlson's Lab calls this a "gimmick," and indeed it is a crude capacitor. Apparently it was common to do this if one only needed a picofarad or two, because it could be achieved just by twisting two wires together (but not connecting them).

[@Coffeeology]

Any idea why that blip of a cap would be needed?

[@McTroyd]

@@Coffeeology Per Mr. Carlson, in very old electronics, where everything was engineered and built by hand, it was uncommon to have masses of parts available on-demand. Generally, one built with whatever one had handy. If one merely needed a couple of picofarads of capacitance (for filtering, decoupling, etc.), it was far more likely there would be scraps of wire available than loose capacitors. This gimmick would serve that purpose; the wire would be twisted until the desired capacitance (or effect of capacitance, like oscillation) was reached, and then cut from the rest of the wire. Nowadays, we have overnight delivery of just about any part we could want. Some of us probably have donor boards lying around to steal parts from too. Still, there's no reason this trick couldn't work today. I gather some ham radio types still use it in homebrew setups. (Way easier to twist/untwist wire than resolder a part when tuning an LC oscillator, I wager.)

[@Professorke]

I admire that modern engineers still venture into old audio equipment. I have stopped working on devices older than 1970 for 20 years. Sometimes the tubes are very hard to find and when you find them, they charge extortionate prices for them. I only do the solid state devices now, but I still enjoy watching the work others do on such tube devices. Keep up the good work, I am enjoying this ☺🥰

[@stevecagle550]

What a mess... Good job... Makes me think about old TV repair days.

[@gibbogle]

No unobtainable ICs! What a joy!

[@wrusty3767]

Also, I was taught during my apprenticeship in the '60s not to solder the wire straight onto the valve lug, but to loop it around after pushing it through and squeezing it with pliers. This gave it mechanical strength and helped avoid dry solder joints. It also looked way better.

[@tasmedic]

yep. the first thing I was taught about soldering is to not use solder as a mechanical connection, it's only for electrical connections.

[@magikjoe3789]

A good electrical joint is first a good mechanical joint. The solder is the lock that holds the mechanical joint in place.

[@renowden2010]

Great to see you working on something twice your age.

[@diabolicalartificer]

The twisted wires are there to tune or tweak the circuit. You find them in Telequipment scopes amongst others. It's a genuine technique, not a bodge. I'd have replaced the wire going to the top cap, the insulation was damaged, still, we all do things different.

[@projectartichoke]

I believe the old-timers called those wound capacitors 'gimmicks'.

[@jozefbubez6116]

Yes! Typically two bits of wire twisted together but these days we might consider a short length of mini coax cable.

[@robinsutcliffe_video_art]

On the modern poly caps, there is an outside foil end, which is not marked, though can be tested. Whilst it is not polarised - the noise floor can significantly increase if the outside foil end is connected incorrectly. The older caps are marked for the outside foil end, you can see the bands around one end - 13:20

[@DelmaRaySmithJr]

My favorite source of educational entertainment, thank you.

[@AdamF1972]

You would be an excellent teacher Mark. I have no skill in your area but you make it look so easy and furthermore...interesting! You should think about doing online workshops for future electronics repairers. People would sign up in droves I'm sure!

[@MorriSoft]

Absolutely agree. Fantastic content, very informative with none of the waffle that some channels have. Brilliant work, I hope we have lots more content to come from Mark, great technician.

[@MattTester]

Fascinating to see the electronics and Mr. Blobby would've been proud of that soldering.

[@kevinisaac9139]

brings back memories at my grand dads workshop on my School holidays helping him repair tbs and radios got me to use the mallard valve tester he used to buy components and give me a project out of practical wireless good times

[@davidvivian596]

Hi Mark, I've just been reading some of the comments further down, and it's clear that some of your audience are very knowledgeable too. Me? I don't know a thing about electrics or electronics, but I find your videos compelling to watch nonetheless. Thank you.

[@jozefbubez6116]

Quite an education for me. Never knew that Ducati began in radio/electronics. That the original reservoir/smoothing caps work after 80 years is truely remarkable. The case sealing must have been of a very high order as also the purity of the aluminium foil. Keep up the good work!

[@nicolasmariotti]

Apparently during WW2 they were also producing large military binoculars (according to R. J. Dalby of Astronomy and Nature TV on KZbin).

[@darkstatehk]

Loved this! I recently re-capped a 1950s Grundig reel to reel using polypropylene caps and it sounded and worked great afterwards. Kinda fun working on old equipment that don’t have PCBs. I also had to map out which caps went where since they were not labelled either.

[@ThePolaroid669]

Find that hard to believe. Have never seen unmarked capacitors in any device.

[@darkstatehk]

@ capacitors values were marked but not with their designation according to the schematics “C1, C2” etc. since there was no PCB there was no silkscreening.

[@LZDEN]

top work Mark,looking forward to part 2.

[@demofilm]

A sticky knob can be a real problem. But you fixed it again . Good job

[@DytliefMoller]

nice to see vintage getting some love. As an 80 baby im very curious for these old components, genius!

[@bjornlangoren3002]

The audio quality of the phonograph was amazing.

[@AustinDeshaies]

One of my first jobs was to work on jukeboxes replacing 15 inch speakers with the new permanent magnet ones. I remember this so well because speakers weigh nothing compared to jukeboxes after the second pickup to replace the speaker at the shop I took one of the old speakers made a template out of 3/4 inch plywood to back set the speaker to allow for incursion with the new ones. This allowed us to stock,repair,replace bulbs in one trip each day doing at least 3 calls per day in one round trip. Wynford sound Scarborough Ontario gave me a bonus and started a creative incentive policy.

[@precbass]

Very interesting Mark.Looking forward to the next one.👍

[@TheElectronicDilettante]

It might not be a 916, 996 SPS or a Panigale. But it’s a beautiful piece of craftsmanship worthy of the name it carries.

[@WeltInScherben]

Very impressive craftmanship, knowledge, patience and attention to detail. Thumbs up!

[@paul1153]

A great part 1 Mark. Looking forward to part 2.

[@ER-qb1nk]

Wow gorgeous radio! Cool mod.

[@hw4527]

Thank you for posting 👍👍

[@jimmyjampantyloons1596]

Fantastic work as always. Love watching your videos. My OCD is on full-tilt because it looked like a lead you cut @ 23:00 fell in the hole...

[@PeterHughes-ne9wz]

Great video, Mark. Always interesting to watch your work...and I know nothing about electronics.

[@knifeswitch5973]

You owe me a new keyboard. I spit my coffee at first glance. It's beautiful!

[@pauldavis6356]

You got lucky on that original Ducati capacitor's red label - I expected to see it turn to dust in your fingers. Well Done.

[@chrissimons9733]

Wow that was very impressive and so detailed. Well done.

[@russellforrest1730]

Excellent work, Mark. Don't envy your job on this one. This kind of valve equipment with no PCB is the stuff of nightmares for me. Gives me colds sweats thinking about making the wrong connection and releasing the magic smoke only to find no parts available😲

[@davidblake6889]

What a lovely old piece of kit. I remember an old Ferguson Radiogram from the fifties that my parents bought new that had a similar style. But it had FM as well, and played 33 and 45 records. Used to listen to 'Journey into Space' on it. Wonderful! BTW. The reason the old caps you tested were reading 'high', is because they have gone electrically leaky. It effectively puts a resistance in parallel with the capacitor. It means that when the tester charges up the capacitor, it takes longer than it should, so it reads a higher capacitance than the true value. It is just as well you replaced them. If you had left them in, it could have damaged some critical and difficult to replace bits and pieces.

[@tomvleh2623]

Hello from slovenia.nice work

[@MichaelJantzen42]

The days before circuit boards and even ceramic strips - scary stuff.

[@alphabeets]

In case anyone is curious, that song from the 78 record at the beginning is called “Swinging Shepherd Blues”.

[@KarldorisLambley]

i like the way the tuning dial has koenigsberg written on it.

[@andreaswestgaard8073]

What a beautiful device! The funny thing is that this can hurt you with ease, just like the motorcycle ⚡

[@eolobrontolo9117]

It comes from the same builder of the motorcycles, from the radio branch. 😊

[@gordonwelcher9598]

The twisted wires are called gimmick capacitors. In this case they have been connected between the two tuned coils in the IF stages. They will increase the coupling between the two tuned circuits. This will increase the sensitivity a bit and also reduce the selectivity. Connected differently they are also used to provide negative feedback to prevent oscillation. Are they added or were they originally installed and shown on the schematic?

[@seankerrigan1627]

Just found you Mark (with the quite recent 25k pre...'twas fun!) then ,'cause of where my enjoyment lies, went looking for tubes, hopefully to get me motivated to carry on with a , about the same vintage, radio into a guitar amp. I just gut them and start anew. This one though, that I'm doing, had a tube or two spare so I've devised an oscillator, LFO, feeding some of the grids of those weirdo heptode thingies, but with a shared triode grid - and cathode (6k8) and it might even work! Man oh man I'd love that OT and speaker, they're lovely! Though I'd also find a place for the turntable electric motor, might even drive a leslie! Oh, good news with the would wires as caps, didn't quite figure that one even though I use the big tuning mechanical caps as treble bypass on volumes so I could do some of those twisties either side to get them more in a suitable range... bit pointless but kinda fun regardless.

[@Timothycan]

I think the reason old capacitors seem to increase in capacitance is a consequence of the way the measuring instrument works. If it works by measuring the rate the capacitor charges up, and assumes the longer they take to charge the higher the capacitance, then it seems reasonable that if the component is 'leaky', that is, it lets some DC current through (acting like a resistor) then it will take longer to charge, so a higher than specified capacitance indicates a 'leaky' capacitor.

[@andygozzo72]

yep, thats pretty much it, leakage will skew the testing unless you use a lcr bridge which has an adjustment for 'loss'/leakage that can cancel it out, these simple testers like in the video cant handle it 😉 but some capacitance drift isnt an issue, or leakage, depends where they are in the circuit , if in a low impedance/low voltage part such as across a cathode bias resistor, no need to replace (except if electrolytic decoupling audio) , similar if ac af negative feedback network from output secondary to bottom end of volume control

[@y_x2]

Yes you should check the leakage first.

[@andygozzo72]

@@y_x2 and/or try to reform..

[@andygozzo72]

should always try to power it up someohow in a controlled manner to make sure no major and possibly unobtainable parts are faulty, before even thinking of recapping, or all that effort and money will be wasted

[@y_x2]

@@andygozzo72 You can only reform electrolytic cap... Wax caps always need to be replaced.

[@MrMaxeemum]

There will be an old man somewhere shouting "I added them to stop oscillation"(I'm only guessing here) There are some old guy tricks to work around maybe some issues with certain valves back in the day. I'm sure we are now losing some of that knowledge of this old technology. I personally would like to attempt a repair on something like this but I could not guarantee a fix. If this came to me I would pass on it, I wouldn't want to ruin such a beautiful device. Looking forward to the speaker repair.

[@kurthuber7639]

Yes like the old Big Iron mainframe computers, everything was tweaked in situ based on the actual hardware quirks, similar to overclocking solid state these days

[@Waldo_Ilowiecki]

Genius.

[@RGD-Games]

when people say 3w of power output.. People automatically giggle, and think its not much.... I once heard a 5w DIY valve amplifier, and it absolutely rattled the walls... i was like :O So now, I know there is more to audio systems, than just the output wattage :)

[@andygozzo72]

proper watts, not these piddly 3w peak music power things 😉 , as a 'rule of thumb' divide pmpo by 4 to get approx rms watts out so, 3w pmpo woild be 0.75w rms 😁

[@TerryClarkAccordioncrazy]

Depends a lot on the speaker efficiency.

[@andygozzo72]

@@TerryClarkAccordioncrazy certainly can...

[@magikjoe3789]

Argos Catalogue Watts we used to call them. My old boss once told a customer who was bragging about his '1000 Watt' speakers.. "bring your kilowatt speakers to me. I will show them 1000 Watts, then shortly afterwards I will show you a bonfire" such a funny bloke.

[@cptyler150]

Fantastic work. I wish they were all moved to a small mb style where all the wires can meet neat in the local soldering

[@rickg8015]

Robert Crumb would love to have that.. Sounds gorgeous too even without a resto-mod..

[@zbaby82]

You make good videos.

[@Horus9339]

That is the most terrifying piece of electronics I have ever seen, and to think that people were sat in a factory soldering this together 80/90 years ago proves we have lost so much education and ability. Well done Mark, you really make me proud to be a subscriber of such a talented chap.

[@glenwhatley4125]

It's incredible that the mfg actually designed this device to have floating multi connections. Were terminal strips particularly expensive back then!

[@fillo1971]

Via passo subito alla part 2 ❤

[@franconero3536]

Your are a magician!

[@jasonturner1045]

very cool piece

[@lycian123]

I did not know you could make a capacitor from a wire round. I now realise how they work but blimey. And I was taught lacing and twining in PO Telecomms in the seventies even though I was the last person to do the course berfore the instructor retired and it was no longer used. Simple skills soon to be forgotten.

[@KarldorisLambley]

i never thought a vintage ducatti could operate with valves made of glass!

[@tordlingvall899]

You said something wrong in the beginning.Normally top cap of HF tubes like 6A8G is the grid. in this case for HF/Mixer. A critical cap is in the audio section is C2 if it leak bring the output tube 6V6G to go with to high current bring the output transformer to burn. It is not so easy when somebody before you tryed to fix things in this old radios without knowledge. Sorry for my bad english (I am a Swedish ) I like your you tube channel . Keep going with the good work!!

[@danhorton6182]

Hello Mark, nice work as always. I’ve seen a lot of your work and I know that you know what you’re doing, but I can’t for the life of me figure out why you’d even think of keeping those main filters in there. While new 10 uF caps would have been completely fine for the rectifier, they do make and I do have 8.2 uF high voltage electrolytics. The reason those measure over 10 even though rated for 8 is because they’re electrically leaky. I just don’t think it’s worth the risk, especially since it seems like this is a commission for a local business where it will be used. Being as old as they are they could short and then you’ll really have to worry about the rectifier or worse the transformer or the business building where it resides. With less than $5 worth of capacitors it would give peace of mind, not to mention new and perfectly functioning filters.

[@Morinaka25]

Yes you are right, old caps that read higher than their rated value on an LCR meter are leaky and should be replaced, it's a false economy to not to. LCR meter does capacitance by seeing how long it takes to charge the cap, and if it's leaky it's going to have more resistance, and will appear to be higher value, it's a shame more people don't realise this.

[@stephenyoud6125]

Brilliant Mark. My go to place for Valve amp repairs and reconditionung ius Uncle Doug's channel. Now for part 2

[@johnpawlicki1184]

In the US those twisted wire capacitors were called gimick capacitors. Common back then.

[@andygozzo72]

yep, in some cases its a necessary tweak, and should not be removed, they're usually there for a good reason

[@andiabwaerts]

best channel!

[@boriss.861]

Insulation tape was around in the 1940's but it was made of cloth. Developed from the mid 1920's

[@deepblueskyshine]

Insulation tape there was in the 40s and even long before them, but it was textile, not PVC.

[@wrusty3767]

Yeah, I remember this style of wiring....it's called "birdcage wiring". Used before there were insulated cables (or maybe because is was cheaper!).

[@glumpy6079]

Smashing stuff.

[@zhaohaigaogu7821]

とても心和らげます。👍❤❤❤

[@superbad123]

great Mark, would be nice to drink a pint with you but I am not from the UK

[@mannye]

"So let's see how well it's been done.." The guy that rewired it suddenly breaks out in a cold sweat.

[@andygozzo72]

you can still get ducati branded capacitors, our tumble dryer has one for the motor run 😉 had to change it a couple of years ago as it went almost open circuit , common problem with modern over miniaturised caps, too thin metallising film on the plastic dielectric

[@glenwhatley4125]

I believe as the ESR goes up, the tester shows higher than spec capacitance.

[@telboy911]

I worked in Electronics for over 40 years. My early career during the 70s was with Rediffusion Television for 13 years (later taken over by Granada Television). My question is; doing all this 'Transformer Winding' and all sorts :-D how do you "make a living" in our modern world!! Maybe you have a full-time job? :-D

[@MendItMark]

You are quite right. I do have a 9-5 day job (nothing to do with electronics), and I often make more money from the KZbin video, than the repair itself. I do however, enjoy the repairs, and making the videos!

[@gasgas2689]

What I want to know is this: in the factory where they were making these radios, amplifiers and so on, did one person build one from start to finish or did one person fit the mains and output transformers, the valve holders and so on, and then someone else wire them in with the resistors and capacitors? My first encounter with a manufacturer flow soldering on pcbs was in 1984.

[@tonyfavarin6746]

I see that according to the data tag that it has 5 valves, being Ducati one assumes that they have desmodromic operation!

[@daleburrell6273]

...whatever THAT means-(!)

[@meistermueller]

2:44 or you can use a DIY kit to build a medium wave Transmitter with a 3.5mm Jack input. There’s a lot on Ali for a few quid It just a bit of solderingwork to do

[@8000Time]

Super !!!

[@petersage5157]

Those old paper & foil capacitors read high when they become leaky.

[@CXensation]

Please note that these old caps will develop significant leakage (DC parallel resistance) over time, which may be the reason why the capacitance reads higher.

[@randalwc]

That pair of 10nf caps you put in, it said 15pf on the cap you took out

[@TheFreshmanWIT]

I'm betting based on the age, that grub screw was a 5/64" (a pretty common size). There only a 1/2 of a thousandth of an inch between the two (

[@dayleedwards3521]

The twisted wire "capacitors" are called gimmicks. Small value caps like this were used to provide a small amount of positive feedback on each IF stage , anode to control grid to increase the gain and narrow the bandwidth in cheap radios like this one. Taken to excess it will make the radio unstable and oscillate. These were added by someone, manufacturers would steer clear of anything dodgy like this.

[@shaunmorrissey7313]

Marvellous stuff, I was unaware Ducati made electronics, ironic really, when Italian bikes had a reputation for doggy/poor electrics. (the 851 is still the sexiest bike ever made)

[@ortzinator]

Yeah they made radios until the Allies blew up their factory, after which they switched to motorcycles.

[@rastaman5105]

Ducati radiogram that,s very rare !!

[@j.a.dowell8229]

Hello from the states ! Just recently found your channel and now I’m a sub! I used to tinker with electronics back in my teens and love watching your content. I have a project for you and would love to give you not info on it. It’s an old cb base station. If there is a way to contact you email or other wise let me know! Thanks !

[@randyberger4910]

The twisted wires are called a gimmic.

[@stephenwilliams926]

Nothing like a rumble of a big V twin lol.

[@WilliamEllison]

Can you print a PCB board for old radios like that?

[@guitar_sir]

You are on GOD level 🙏

[@highpath4776]

78s are about a £1 a pop in charity shops.

[@mmols9904]

your funny Mark , i laugh my head off with you , how you fix problems hahahaha so funny ,, i look a lot off your adventures how you fix stuff :-)

[@frankowalker4662]

The inside of that I.F. transformer can was not what I was expecting to see.

[@graemezimmer604]

Yeah, the twisted wire cap is called a "gimmick capacitor". The I.F. transformer is a classic "Optimum Coupled, Double Tuned" transformer. It is tuned by means of the two slugs and the fixed caps, so that gimmick cap is entirely redundant. You should have deleted it (although maybe the slug was broken, so the previous Tech couldn't adjust it). However the little "coil of wire" caps were very commonly used as trimmers and are original..

[@GlenWhatley]

Sometimes the 'loose' wires that seem to go nowhere, are actually called 'Gimmicks' that act like high value caps or inductors. So you have to be careful with them as well as the dress of wires, given moving anything in a tuned circuit can affect the alignment. I'm sure that's not news to you!

[@michaelproust7891]

Could you please explain how a twisted wire can achieve capacitance? The other thing you mentioned in waveform-modulator video, was that there were polarised, as against non polarised capacitors and their position in the power circuit governed whether they needed replacing, could you possibly flesh that out.

[@LilMissMurder3409]

A capacitor, in its most simple description, consists two conductors separated by an insulator/dielectric. If you have two bare wires close but not touching, technically you have capacitance because the air gap acts as the insulator. (As an aside, this is how lightning works - you have two conductors, the clouds with their built-up charge, and the earth. The atmosphere in between acts as the insulator. A lightning strike occurs when the breakdown voltage of the system is reached - the voltage becomes high enough for for the resistance of the air to be overcome and current can flow. In an electrical capacitor, when this happens the cap is damaged. But I digress).

[@rsz90182]

Someone told me a long time ago, the objective is to keep the smoke inside the wires and don't let it out.

[@rogermiullercalsinachahui7750]

saludos desde peru amigo

[@ecc84]

Are you going to give us a video on reconing a speaker Mark? I hope so as i have up in my loft a 50watt guitar amp from the 60's that needs reconing and maybe i'll give it a try :-)

[@dewexdewex]

I had to pause to check all the interesting looking transmitter locations. The Beromuenster one piqued my interest. I thought it was in reference to Muenster in NRW, Germany, but it isn't. Blosenbergturm outside Beromünster Beromünster is the site of the Blosenbergturm, a 215-217 m (705-712 ft) tall radio tower built in 1937.[11][12] The castle at Beromünster was the site of one of the first printing presses in Switzerland, built in 1470. en.wikipedia.org/wiki/Berom%C3%BCnster

[@everTriumph]

Braver man than I...

[@lyntonprescott3412]

Ever heard of J hooks, or twisted wire spring connectors?