Restoring an HP 150A Oscilloscope (Part 4) - Victory!

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It was a brutally long repair, but we got there! I won’t spoil too much, but in our diagnosing process we traveled all over the scope, replacing a litany of parts, but in this episode, we finally crack the code and emerge victorious. It’s a good day indeed!
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Music:
Artist: Gux
Title: Secret of Mana "Smooth Mana"
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Intro Music adapted from:
Artist: The Runaway Five
Title: The Shinra Shuffle
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Thanks for watching!
Chapters
0:00 Intro
1:48 The Game Plan
4:18 Recapping
5:16 Testing
7:41 Intensity Issues
11:46 HV Section Rework
13:18 Testing Again
14:12 Oopsie
15:23 HV Section Rework… Again
16:17 Even More Testing
18:21 Vertical Tuning
19:37 Horizontal Tuning
21:26 Victory
24:08 Bunny!

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5 июл 2024

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Комментарии : 140

@RWBHere 3 месяца назад

Who else was shouting at the screen, 'Turn the brightness down! You're burning the phosphor on an expensive and hard to replace tube.' The brightness should be no higher than the display on your modern 'scope. Any brighter and it begins to defocus as the trace spreads across the phosphor. That threshold should be your guide. That said, it's great that you managed to fix the Old Lady. 🙂👍

@CuriousMarc 2 года назад

Nice! The rabbit works again at the end, I see.

@UsagiElectric 2 года назад

The bunny was giving the final quality control check! Though, she may have been bribed with treats, haha.

@lovatomi 2 года назад

Honestly the most emotionally resonant oscilloscope repair mini-series I could possibly imagine. This is prime-time stuff. Nicely done!

@UsagiElectric 2 года назад

Haha, thank you! It was definitely a journey to get it up and going again, but totally worth it. Thanks for checking the videos out!

@tomohlsson9045 2 года назад

I'm so glad you never gave up! I just grinned along with you there at the end. Wow, well done, well done indeed!

@UsagiElectric 2 года назад

Thank you so much! It was a true battle, but in the end it was totally worth it!

@bentbilliard Год назад

"Why is he excited about old equipment" I get this all the time too... but the ones who get it get it. And if it's exiting for me alone, that's already a cool thing by itself.

@paulawillaminachandler-ren3725 2 года назад

April 1956 not 70 year old yet. This was a very enjoyable series. Well done!

@UsagiElectric 2 года назад

Thank you so much! You got me, only 65 years old, which is still pretty impressive given how accurate it is!

@paulawillaminachandler-ren3725 2 года назад

@@UsagiElectric Ha ha, you should have a look at 12Voltsvids channel on calibrating it. I love the hair tubeboy.

@mauriciosinigaglia4761 Год назад

Good job. It is very gratifying to see such a quality equipment back in action. Nowadays, you can buy a good oscilloscope for a few hundred dollars. But 60 years ago, few people or institutions had the capital to pay for such equipment. They were works of art that brought together the cutting edge technology of their time.

@Pulverrostmannen 2 года назад

yep and the golden rule about all vintage gear such as this here, never trust the capacitors because they will have excessive leakage which will fry resistors and other stuff on the way. the bumblebee or black beauty as you call them and wax caps allways need replacing but also electrolytic etc tend to be gone too. you can normally trust most Mica style which is the square ones you can see in the device and or mustard caps and film caps generally don´t fail as often as the other ones, except Rifas, oooo the shivers I get from these Rifa ones, destroyer of equipment and ruins of life. they must be replaced on sight! but I did not see any here because your device is a bit older than these caps anyway. good job restoring it in the end!

@UsagiElectric 2 года назад

Thank you! The black beauty / bumblebee caps were almost all cracked from stem to stern, it's a miracle they didn't take out more components when they died. The HV caps were surprisingly weak too, I ended up having to replace all of the HV ones with modern WIMA caps and the machine works beautifully well again now! I thankfully haven't had any run-ins with any RIFAs, but then again, all my equipment predates RIFAs by about 15 years.

@docfoot316 2 года назад

I can see the light ,well done and you stuck with it .

@UsagiElectric 2 года назад

It was certainly a battle to get there, but I'm glad I did because it's a brilliant "little" scope!

@AE1PT Год назад

I enjoyed this series, having enjoyed working with HP stuff of this vintage years ago as a service tech. What surprised me is your reticence to 'shotgun' replace all of the paper caps at once. As my hobby these days is restoring old amateur and test gear--those caps have either failed, changed, or are not far from it. My first order of business is to first make a parts list of the caps and then check any high-ohm resistors for tolerance. Then add the inevatible ones to the list. Follow up with a thorough internal cleaning of control contacts and potentiometers--followed by tube testing. Although such does not create as many "interesting" adventures in troubleshooting--that way of doing things saves a lot of time and smoke--and usually leads directly to the alignment. Anyway, keep on enjoying these beasts!

@vicmiller7191 2 года назад

You could enjoy a conversation with the RU-vidr Mr Carlson lab. This guy is a genius when it comes to tubes for all kinds of stuff. And he has one of largest TEK scope collection i have ever seen . And if they work and most if not all do work he has done his magic to restore them and make then as if they just came off the factory floor... nice video and thanks for sharing... Vic

@UsagiElectric 2 года назад

Thank you so much! Mr. Carlson makes some stunningly good content, and you're right, his Tektronix collection is simply one of the best in the world! Though, if you look closely on his shop tour video, it looks like he's got an HP frequency counter (he mentions these), an HP VTVM, and an HP lab power supply hiding out among the Tek gear.

@vicmiller7191 2 года назад

@@UsagiElectric Yes he does and of course a whole lot of other very rare and interesting test gear from years past. Take care

@justovision 2 года назад

That scope is a beast! Congrats on taming it!

@justovision 2 года назад

Also I have a signal generator in the same family that was made in the early 70s. Those things were in production for 30-40 years with some internal revisions but seemingly the exact same chassis.

@UsagiElectric 2 года назад

@@justovision Thank you so much! And yeah, the 200 series Oscilator was such a rock solid design, HP sold them for years and years! It's a really great little oscillator and I always love seeing them still in use. Mine needs a little adjustment to align the dial with the frequency better, and the amplitude portion has been misbehaving a bit lately, so I'll have to dive into it again soon to sort it completely.

@iygor 2 года назад

Well done. . . Well done sir. Never doubted you would find the issues with this esoteric piece of hardware. Again Well done.

@UsagiElectric 2 года назад

Thank you so much! I'm glad at least one of us never doubted I would find the issues, because I most certainly had my doubts, haha.

@frankowalker4662 2 года назад

Brilliant. What an EPIC success. Realy well done on bringing this beautiful HP scope back to life.

@UsagiElectric 2 года назад

Thank you so much! Honestly, if it wasn't such a gorgeous looking scope, I may have given up at one point, haha. But, I'm glad I stuck with it as it's just a gorgeous scope and seems to be absolutely rock solid now!

@brianclimbs1509 2 года назад

You inspired me to have another look at why my Tektronix 561A wasn't working, and I figured out the "on" switch just needed some contact cleaner!

@UsagiElectric 2 года назад

That's excellent! I wish the HP had just need some contact cleaner, haha. The Tek 561A is a gorgeous little hybrid scope (I was pretty surprised to see that it uses some transistors in the power supply section, that's really cool). I'm glad you got it going again, I love seeing more old gear getting used again!

@brianclimbs1509 2 года назад

@@UsagiElectric I might need to get a new switch or give the current one a bath to make it work consistently, and the type 3A1 vertical amplifier (which also uses a surprising number of transistors) will definitely require attention, but it really is an impressive piece of technology. But no match for this pure tube piece of art you restored!

@acoustic61 2 года назад

Your videos are amazing! You're sharp and very resourceful. I once worked an engineer who was like you and really learned a lot from him. I miss those days.

@UsagiElectric 2 года назад

Thank you so much! Though, I don't know if I'd say I was sharp, I made some very daft mistakes during this resto. I would more say that I'm just very stubborn, haha.

@akkudakkupl 2 года назад

Flux your desoldering braid and it will suck up solder like crazy. I usually heat up some flux with my soldering iron (rosin flux) and dip a few centimeters of braid as needed. The difference is colossal.

@UsagiElectric 2 года назад

That's a really, really good idea! I don't know why I never though it that, but it makes total sense! Thanks!

@c00kie84 2 года назад

Brilliant! Thanks for bringing us along on your rollercoaster journey. Great to see it so rock solid stable at the end. Well done!

@UsagiElectric 2 года назад

Thank you so much! It was a brutal restoration, but well worth it in the end, it's such a cool scope!

@VandalIO 2 года назад

Awesome ! This was a great journey it was a very emotional suspenseful ride for everyone. And I’m glad it works like a charm Congrats 🥳

@UsagiElectric 2 года назад

Thank you very much! It was a tough couple of weeks (and a lot of Mouser parts orders), but I'm quite happy with how it all came together!

@mikeras27 2 года назад

congratulations! awesome work all through Part1 to 4. Thanks for sharing! I smiled all the way to your victory!

@UsagiElectric 2 года назад

Thank you so much! And thanks for checking out the videos, there's more vintage HP repairs to come!

@MichaelRusso 2 месяца назад

Crazy awesome project!

@michaelmiller641 2 года назад

It's great when you finally get something working! Well done!

@UsagiElectric 2 года назад

Oh man, that feeling when it was all in spec was absolutely worth the effort! Thank you so much!

@viorelparaschivoiu8882 2 года назад

Congrats on your victory and thank you for a well presented series. If there is one thing to take away from your adventure though, I would quote Paul (Mr Carlson's lab) "these capacitors are outta there!". A "blanket" replacement of capacitors may sound unencumbered by analytical thought process but it would have saved you at least two episodes' worth of headache. Not to say it wasn't entertaining to watch though. But Paul demonstrates over and over again these old foil capacitors are all dead. I don't think in his entire video history he's found more than a handful still good in probably thousands replaced and tested. Following his example I got myself a capacitor tester and had the same experience. Not one good in the handful of restorations I have done. And if it were my money, I would change all those black 6kV capacitors as well. Cheap insurance.

@tstahlfsu 2 года назад

So happy to see this working!!! Great job and what a slog!!!!

@UsagiElectric 2 года назад

Thank you so much! It was a true battle, but the result was totally worth it!

@AlejandroLopez-qd3xm 2 года назад

Congrats! Another step into your HP collection.

@UsagiElectric 2 года назад

Thank you! And I rewarded myself by buying yet another piece of old HP equipment that needs some restoration work. I have this dream of building a little roll around cart with all my test gear needs taken care of by vintage HP gear. Though, if I turn everything on at once, it'll end up raising the temperature of the room by a pretty substantial amount, haha.

@vincei4252 2 года назад

Victory ? !! Congratulations, man!

@UsagiElectric 2 года назад

Thank you so much!

@diskcopy 2 года назад

Good Job! Very cool to see it working.

@UsagiElectric 2 года назад

Thank you so much! I'm so happy to have it up and going and looking brilliant, it's a really great scope!

@Zone1242 2 года назад

Well done - nice repair.

@UsagiElectric 2 года назад

Thank you very much!

@bronka42 2 года назад

congratulations!!!

@UsagiElectric 2 года назад

Thank you!

@TeslaTales59 2 года назад

Fine job sir!

@UsagiElectric 2 года назад

Thank you very much!

@marka1986 2 года назад

Nice scope. Great job getting it finished.

@UsagiElectric 2 года назад

Thank you so much!

@ThomasJakober 2 года назад

Congrats for this nice intense restoration. I like the way you bend the capacitor wires to the correct length. May be i'll change the way i do it from now on.

@UsagiElectric 2 года назад

Thank you! I needed to get those caps to be like axial caps, but I was really worried about putting stress on the epoxy coating, so I did the slightly extravagant bending, which was probably overkill, but I think it looked cool, haha.

@MUHAMMADYAWARIFRAHEEM 2 года назад

Very nice video Sir....and cute bunny is testing🐇😃🤗

@UsagiElectric 2 года назад

Thank you! And the bunny was perform final quality control inspections, though she may have been bribed with treats, haha.

@KolliRail 2 года назад

Great success! And well deserved!

@UsagiElectric 2 года назад

Thank you so much!

@andymouse 2 года назад

Awesome ! well done to you et al .....cheers.

@UsagiElectric 2 года назад

Thank you so much!

@williefleete 2 года назад

Well done

@UsagiElectric 2 года назад

Thank you!

@robot797 2 года назад

good job my friend still want to have that box'o tubes its packed and waiting on your awnser

@glufke 2 года назад

Awesome!

@UsagiElectric 2 года назад

Thank you!

@crasbee 2 года назад

I'm really happy to see the WIMA caps in there. Now a little suggestion of mine lives on in an ancient HP scope in Texas :D

@UsagiElectric 2 года назад

Those WIMA caps were a life saver! And you were right, they're really high quality an excellent caps!

@akkudakkupl 2 года назад

Selenium rectifier (gray plates stack close to power supply), lets pray it doesn't overheat, otherwise you will have to live with a terrible rotten smell for some time until it goes away. Big Clive did a video on them some time ago.

@vincei4252 2 года назад

I'd just preemptively replace that sucker.

@teslakovalaborator 2 года назад

@@vincei4252 Not so blindly, you have to accout for its voltage drop, the circuit might be intolerant to such low drop as that of silicon diode

@vincei4252 2 года назад

@@teslakovalaborator Of course, however, depending on where the rectifier is used the drop across it might be insignificant. All requires an assessment which I didn't go into in my reply.

@UsagiElectric 2 года назад

Thanks for pointing that out! I had a few other people tell me I should replace that as well. I had no idea that selenium rectifiers were known to be fairly unreliable. I did some digging and it's the full-bridge rectifier for one of the DC heater chains. So, if it goes, it won't take anything valuable with it, which is good. But, it would definitely be a good thing to replace before it does cause a problem. Fortunately, I know the voltages I need and the power level it should be delivering, so I can get a modern full-bridge rectifier and run a series dropper resistor to get it nice and safe!

@akkudakkupl 2 года назад

Congratulations :-)

@UsagiElectric 2 года назад

Thank you so much!

@simonkormendy849 2 года назад

I've got an old Telequipment D33R Tube Oscilloscope that I would love to restore back to full operation, trouble is, it needs a replacement CRT because the original one has a great big hole in the screen, and is therefore no good anymore.

@UsagiElectric 2 года назад

Very cool! The D33R is the rack mounted version, right? That's an awesome looking scope. That's no fun about the CRT though, I got lucky in that this one was in excellent condition, but a hole in the phosphor is one of those things you can't really repair. I hope you find a good CRT for it one of these days!

@Bianchi77 2 года назад

Nice video, thank you :)

@UsagiElectric 2 года назад

Thank you very much!

@seemeknowme 2 года назад

Your journey with this scope seems very similar to mine from last year, restoring a Dumont Fairchild 766H hybrid oscilloscope. Nice work!

@UsagiElectric 2 года назад

THank you! And that Fairchild 766H is a very cool scope too! Googling it led me to a great build thread on Antiqueradios (link below). It seems the author went through a pretty intense repair too. Could it be I found yours? Either way, the Fairchild scope looks to be a great little (well, not so little) scope! www.antiqueradios.com/forums/viewtopic.php?f=8&t=380702

@seemeknowme 2 года назад

@@UsagiElectric That is indeed my article, yes! I have not aligned it yet, but I like to use it for less serious stuff. Funny story, my HP1740A scope died and instead of buying the part to fix it, I bought three of the Fairchild scopes! I just fell in love with their particular look as soon as I saw them! I suppose you may have read that in the article though. Your series was nostalgic for me, even though it hasn't been very long since I did my scope.

@retrobreutje 2 года назад

Congratulation! You ispire me!

@UsagiElectric 2 года назад

THank you! And I'm happy to hear that my videos have inspired you a bit!

@georgegonzalez2476 2 года назад

Good job! Now in your spare time you could change all the other tubular capacitors in there. Especially the wax, bumblebee, and high voltage ones. They are probably leaky or about to short out.

@UsagiElectric 2 года назад

Thank you! I actually did go through and replace every wax and bumblebee capacitor on the machine. There's still about 5 or so HV caps that are the original caps though, but I figure that as long as its working as well as it is, and it's working brilliantly at the moment, I'll leave them be!

@georgegonzalez2476 Год назад

@@UsagiElectric That's fine, but you might want to stock up on high-voltage capacitors with leads, they are getting scarce and very expensive. I had a hard time finding some 3KV capacitors for a Tek scope. Neither DigiKey nor Mouser have a good selection of them anymore. The ones they have in stock are like $44 EACH !!!

@gammaleader96 2 года назад

Very nice, I know your pain with the wafer switch, I did a Grundig Oszillograph G4 a while ago. These units are built beautifully but a pain to work with if you need to access a capacitor deep down under a wafer switch assembly. Your CRT seems to have a lot of life left in it too. I guess you are well equipped for the cold months. If you leave the covers open, it makes a nice christmas decoration, with all the tubes.

@UsagiElectric 2 года назад

Thank you! HP, in all their wonderful foresight, made the switch easily removable, but then put very short wires from the switch to the main PCB that were soldered in place! I had to kind of twist it out of the way to barely get enough room. It was... tough to say the least, haha. The CRT looks really brilliant and may be a testament to how much of this scopes life was spent sitting unused on a shelf somewhere. Either way, I'm properly happy with the result!

@tim_bbq1008 2 года назад

While a beautiful piece of equipment, and a great victory to bring that o'scope back to life, I wonder if a new modern piece of equipment would be more practical for a casual user? Regardless, I was proud to see that your long journey of repairs has paid off and it is again worthy HP test equipment gear. Congrats.

@UsagiElectric 2 года назад

Thank you! And HP really did make some gorgeous equipment! For a more casual user, a modern scope is definitely much more practical, if only for the fact that it won't weight a ton, haha. I would actually suggest that if someone were to be getting their first scope, that they should instead go for an analog scope from the 80s-ish. These can often be found for under $100 on eBay and usually are still totally rock solid. I have an old BK Precision 2120 on my desk that I use for most stuff, and it's great. Thanks for checking out the videos!

@KeritechElectronics 2 года назад

4:28 - The Most Hated Tool On This Channel? :) (Skunkie Design reference) 20:30 IMO it's better to measure time between zero crossings on the rising (or falling) edges as peaks on the sine wave are kinda fuzzy and the measurement won't be as precise. Soooooo wonderful to see your success! I bet Paul Carlson would agree on that. By the way, I love your upbeat and jolly attitude :) And wascally wabbits :)

@UsagiElectric 2 года назад

Thank you so much, it feels awesome to see the scope back alive! (And I would be totally humbled if Mr. Carlson followed this series, that would be awesome) The little pliers was totally me being way too lazy to walk out to the garage and get the correctly sized socket, haha. The zero crossings is a way better way of precisely measuring frequency, I don't know why I didn't think of that. I blame on being way to excited to see it working that my brain stopped functioning correctly!

@jj74qformerlyjailbreak3 2 года назад

I’m trying to find service manuals to Dumont 2100g 10Mhz 2 channel scope. No luck. Any suggestions of where finding old specs of these almost forgotten devices? Thanks and great content. God Bless.

@ludmilascoles1195 2 года назад

Great work, but that selenium rectifier has to go if you plan to use this scope. They are just time bombs waiting to go off. You might be lucky if it is on a low voltage rail, the do last when uses for under 20v

@UsagiElectric 2 года назад

Thank you! Interesting, I didn't know that Selenium rectifiers were that sketchy, but I've had a couple people tell me to look into that now. My little 200CD oscillator has been misbehaving a bit lately, so when I dig into that one again, I'll also crack the 150A open and see if I can do something about that Selenium rectifier!

@ludmilascoles1195 2 года назад

@@UsagiElectric I will check and see if there was an official 'HP-Mod Kit' for it. Most likely was as this was a popular CRO.

@simonkormendy849 2 года назад

The thing about those old Selenium Diode rectifiers is that when they finally give up the ghost, they let out a very pungent smell that persists for a long time.

@ludmilascoles1195 2 года назад

I cheched. I was mistaken it was a NOS Tektronix mod kit I saw.

@Dr_Mario2007 2 года назад

That old oscilloscope is hard to work on due to how complicated it is internally, and yet you successfully brought it to specs. Looks good! 👍 If it has video or signal input somewhere in the back of oscilloscope, why not put together a small computer with Cortex M4 / M7 microcontroller to display the data in overlay with the original signal being measured, like voltage and frequency?

@MrRedwires 2 года назад

I'm pretty sure that CRT is working hard enough as-is just displaying the signal data. Displaying extra data would require tapping in to the entire signal generation and MUXing the horizontal/vertical position so the MCU can control the dot position and write something. It's doable, but it'd be a big modification to the rest of the system.

@Dr_Mario2007 2 года назад

@@MrRedwires True, however some oscilloscope can be left original out of box without any mods before using such setups. I know of a few HP oscilloscopes that had that feature before they switched to 100% digital oscilloscope hardware.

@UsagiElectric 2 года назад

Thank you so much! It was a true battle to get there, but the result was totally worth it! It could be done to have a data overlay like that, but it would be well beyond my capabilities. It would also limit the minimum speed the scope could display. Even with two traces, I can start to see visible flicker if I get to too low of a frequency. Most importantly though, I've got an old HP frequency counter sitting in the garage that needs a resto, and so why do a data overlay when you can buy more vintage HP stuff!

@stevefriedl3983 2 года назад

So, did you get the serial protocol decode working? Maybe show that in part 5? 🙂

@skeezixcodejedi 2 года назад

Wow! Nice job! I'd have given up long ago :)

@UsagiElectric 2 года назад

THank you! And honestly, if the scope wasn't such a cool looking scope, I probably would have given up a long time ago too. But, I'm glad I stuck with it because it's a really great scope to use now! Though, it's still a bit too heavy to be moving around - either that or I need to work out more, haha.

@skeezixcodejedi 2 года назад

@@UsagiElectric also its great to keep an analog scope around. They’re awesome and beautiful .. and I like to see the analog wiggle .. like an analog voltmeter you can see the needle wiggle easier sometimes than in digital ..

@ZombieGuides Год назад

What does something like this run a person? Like working vs non, what is the value if you're looking to own a 150a? I don't see any for sale around really, so they must be kinda rare, but are they expensive when you do find em?

@mehmetselvi8242 2 года назад

I really like the lines on the oscilloscope screen. Is it possible to make an artificial screen that will look like this on my desk?

@UsagiElectric 2 года назад

Thank you! It's totally possible to build small oscilloscopes with modern components, you can even buy kits. But, one of the reasons that scope looks so good in my opinion is because it's using a pretty high quality CRT (Cathode Ray Tube). These are often quite large and use pretty high voltages, but old scope CRTs are pretty common and not that expensive, so it's definitely possible to build something with one. Check this out for some cool ideas: www.sgitheach.org.uk/scope3.html

@mehmetselvi8242 2 года назад

@@UsagiElectric Thank you very much for your detailed answer. The website turned everything I thought into a set. Wonderful! Have a nice day, good work.

@vincei4252 2 года назад

Wait, did you say -5000V and 6000V a few seconds earlier? Yikes, I am truly terrified now too. I built a regulated 2000V power supply for some photomultiplier experiments and that terrifies me too. All pets are banned from the lab when that sucker is running. Unsurprisingly those experiments have been on the shelf for a very long time.

@UsagiElectric 2 года назад

Yup! There's some proper high voltage floating around in there for the CRT circuit. I was super nervous working on it with the case off it, but I was just focusing on being methodical and cautious and it all worked out alright!

@adailyllama4786 2 года назад

Are the Usagi Electric t-shirts still available?

@UsagiElectric 2 года назад

Yup! They're available here: my-store-11554688.creator-spring.com/

@mominkhan7247 2 года назад

varey nice

@Puner54 2 года назад

How about Fixing an old Textronix 465B Oscilloscope?

@UsagiElectric 2 года назад

Tektronix had some amazing engineering in their old scopes, and they're surprisingly constructed very differently than the old HP here. I would love to take a stab at an old Tek scope someday, but I don't have any Tek stuff in the collection.

@AlienLogic775 2 года назад

I think that the capacitor shorting burned that poor resistor. To avoid burning that precious hv transformer I’ll suggest to replace the other hv bumblebee capacitors.

@UsagiElectric 2 года назад

Yeah, that's definitely possible! At the moment, everything seems to be working correctly, but If I notice any fluctuations in the brightness, I'll definitely shut the system down and replace the other HV caps as well!

@AlienLogic775 2 года назад

@@UsagiElectric HV transformers are now the rarest things on earth :) Almost burned one on a delicious Tektronix Type 310A. By the way, very beautiful videos! Love your content!

@UsagiElectric 2 года назад

@@AlienLogic775 Thank you! If I ever get the HV stuff out of the box again, I'll take a look at replacing those caps! You're right, HV transformers are near impossible to find these days, so it makes sense to take whatever precautions we can to keep them going for as long as possible.

@VandalIO 2 года назад

I wanna see triangular waves in your crt scope

@UsagiElectric 2 года назад

Here ya go! i.postimg.cc/NfyjWz6B/IMAG0234.jpg i.postimg.cc/sfH2HrZT/IMAG0235.jpg

@VandalIO 2 года назад

@@UsagiElectric woah ! The triangular waves are absolutely beautiful 🤩!

@user-folk1987 2 года назад

Control carbon resistor too. Sometimes it fullshit

@UsagiElectric 2 года назад

Yup, those old carbon composition resistors can drift quite a lot. I tested most of them though and they were mostly within their 10% range. Some had drifted slightly beyond, but that could be corrected for with some potentiometers in other places.

@DIYTAO 2 года назад

Cool, man. capacitors

@DIYTAO 2 года назад

(Yourtube messes up comments) .. Old Paper-vax capacitors leak DC so they alter bias of tubes and can overheat/burn coils. It's smarter to switch them all the same time since the rest of them will get bad in time.

@UsagiElectric 2 года назад

Thank you! At this point, I think I've changed all the paper-wax capacitors and bumblebee/black beauty caps in the entire system, so I should be good!

@VandalIO 2 года назад

11:36 it appears this is a carbon film resistor .. why didn’t you go for metal film resistor they have lower noise

@UsagiElectric 2 года назад

I had a really tough time finding a 4.15M 1W resistor. I bought some other metal film resistors that I could put in parallel, but I decided to give that one a shot and see how it did. So far it seems to be pretty stable and the picture looks great. If I have any issues in the future, I've got my other resistors on standby to try instead.