1942 Ducati Radiogram Repair (Part 1)
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- เผยแพร่เมื่อ 5 ก.ย. 2024
- Mark checks over an 80 year old Ducati RR3405 Radiogram. In this episode, the radio chassis gets an overhaul - and a few surprises to come! It appeared to work, but maybe it shouldn't have.
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
Yep.
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
I believe the old-timers called those wound capacitors 'gimmicks'.
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.
nice to see vintage getting some love. As an 80 baby im very curious for these old components, genius!
Great to see you working on something twice your age.
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.
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 :)
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 😁
Depends a lot on the speaker efficiency.
@@TerryClarkAccordioncrazy certainly can...
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.
You owe me a new keyboard. I spit my coffee at first glance. It's beautiful!
Fascinating to see the electronics and Mr. Blobby would've been proud of that soldering.
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!
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.
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.
Very impressive craftmanship, knowledge, patience and attention to detail. Thumbs up!
Very interesting Mark.Looking forward to the next one.👍
What a mess... Good job... Makes me think about old TV repair days.
top work Mark,looking forward to part 2.
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
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.
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
Yes you should check the leakage first.
@@y_x2 and/or try to reform..
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
@@andygozzo72 You can only reform electrolytic cap... Wax caps always need to be replaced.
The days before circuit boards and even ceramic strips - scary stuff.
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.
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
A great part 1 Mark. Looking forward to part 2.
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
A sticky knob can be a real problem. But you fixed it again . Good job
What a beautiful device! The funny thing is that this can hurt you with ease, just like the motorcycle ⚡
It comes from the same builder of the motorcycles, from the radio branch. 😊
In the US those twisted wire capacitors were called gimick capacitors. Common back then.
yep, in some cases its a necessary tweak, and should not be removed, they're usually there for a good reason
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!!
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.
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😲
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?
Wow that was very impressive and so detailed. Well done.
Genius.
Great video, Mark. Always interesting to watch your work...and I know nothing about electronics.
Robert Crumb would love to have that.. Sounds gorgeous too even without a resto-mod..
Via passo subito alla part 2 ❤
I see that according to the data tag that it has 5 valves, being Ducati one assumes that they have desmodromic operation!
...whatever THAT means-(!)
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..
great Mark, would be nice to drink a pint with you but I am not from the UK
Fantastic work. I wish they were all moved to a small mb style where all the wires can meet neat in the local soldering
Yeah, I remember this style of wiring....it's called "birdcage wiring". Used before there were insulated cables (or maybe because is was cheaper!).
Insulation tape there was in the 40s and even long before them, but it was textile, not PVC.
Wow gorgeous radio! Cool mod.
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...
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
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 TH-cam video, than the repair itself. I do however, enjoy the repairs, and making the videos!
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 (
Insulation tape was around in the 1940's but it was made of cloth. Developed from the mid 1920's
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.
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.
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.
Super !!!
Mr. Carlsons lab, he is the guru of vintage wireless and capacitors turn out to be directional. Try it and see!
best channel!
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)
Yeah they made radios until the Allies blew up their factory, after which they switched to motorcycles.
You make good videos.
Ducati radiogram that,s very rare !!
Thank you for posting 👍👍
They stopped making electronics when the factory got bombed.the allied operation was called operation pancake
Ducati Energia still exists, they mainly make motor run capacitors.
I'm surprised that there was any civilian radios being made especially of that quality, considering there was a major war going on.
In 1942, Italy did not experience much of the war, as they were Axis allies.
Hello from slovenia.nice work
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
Swinging Shepherd Blues !
Yeah, I worked with a saxophonist here in Canada who made a lot of money from that song. Hmmmmmm.
The twisted wires are called a gimmic.
Mark you dld well to fix this birds nest and sort out this mess nice piece of furniture
78s are about a £1 a pop in charity shops.
Smashing stuff.
WOW almost Marconi-old. Died: July 20, 1937
I've been an electronic hobbyist for years, although I never took it to this guy's level. And, people want me to fix old vacuum tube equipment, on occasion, and I'm like I don't want to get involved in things like this.
If it were me I'd have a cabinet craftsmen refinish the cabinet and then put a new expensive turntable in it as part of my home audio setup.
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
Anode…I think that’s the grid…Nevermind, anode appears right.
Twisted wire with end cut off = gimmick capacitor…usually a few puffs
You are on GOD level 🙏
Nothing like a rumble of a big V twin lol.
Braver man than I...
It appears that Bubba has been at that radio.
Brilliant Mark. My go to place for Valve amp repairs and reconditionung ius Uncle Doug's channel. Now for part 2
What I dont understand is if you have the schematic why not rip it all out and put it back nice and proper with all the caps and wires replaced or updated so it looks nice and proper. Unless it is to preserve the way it was originally wired? I would think all the wires and things need to come out...
That first valve with the wire on top is not anode it is control grid. Pin3 and 6 the anodes pin 3 being the main and pin 6 being the oscillator supply.
yep, most of those octal valves dont have top cap anode , similar with the later 6.3v UX based types
saludos desde peru amigo
Insulation tape was around in the 1940s, but it was cloth tape not plastic.
I think this device is before 1942 (probably 1938) because during the WW2 le production was converted in military radio device and in 1943 the factory of the neiborough of Borgo Panigale was bombed by american B17.
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.
3M company engineers invented "modern" vinyl electrical tape just after WWII ended but it wouldn't have looked like that as black became the standard color later (and this radio predates the tape by a few years for sure), and gutta-percha/Chatterton's "tape" would have been around about 100 years earlier but this obviously wasn't that, maybe it had some originally?
Why did a wartime Italian radio use American series valves? Was this before the sanctions were imposed? These tubes all had European octal E (6.3 volt) equivalents.
I can't believe you don't make a mechanical connection
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 :-)
I bet you learned your skills in the Royal Navy..? Not many know about thrapping.
the weird capacitor is a "tickler" coil....
Found 1 ;) just need my brew now
Can you print a PCB board for old radios like that?
Ahh Bluetooth, little AM transmitter would be better and more fun!
Ever heard of J hooks, or twisted wire spring connectors?
I have never seen a soldering iron like the one you use. What make is it? Cheers Ian
This is not electronics repair, this is wireframe soldering! 🤣
Ducatti made cameras too
Where are you getting the schematics from? 🧐
Do you have a battletrak video?
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Who needs a PCB when you can just wire-solder everything like a cheap electric guitar :D
Wow someone butchered that in the past . Did you spot that heat damaged resistor when you were replacing the braided connection that annoyed you?
Hello salom
😮 wuao funciona