CuriousMarc - 2024-11-08
With great difficulty, we repair our Patron-donated HP 115BR divider and clock, an instrument that was once used to synchronize all of the world's atomic clocks. It requires a bit of a fight, but in the end, we are rewarded with the most steampunk atomic clock ever! HP 115BR Playlist: https://www.youtube.com/playlist?list=PL-_93BVApb5-_7sWRxQ0on8vNy7_H-zxS Atomic clock playlist: https://youtube.com/playlist?list=PL-_93BVApb59F6V90OdcqVofqVWceR6Dk Link to the HP 115BR Manual: https://bama.edebris.com/download/hp/115br/HP_115BR_frequency_divider_and_clock_op_service_manual_1967.pdf Stuff that supports the channel: - Support us on Patreon: https://www.patreon.com/curiousmarc - Amazon links for the tools I use in the lab: https://www.curiousmarc.com/amazon-links - Channel merch on Fourthwall: https://curiousmarc-shop.fourthwall.com - Legacy channel merch on Teespring (I don't have everything transferred to Fourthwall yet): https://teespring.com/stores/curiousmarcs-store "Elevator Music" Credit: Crinoline Dreams by Kevin MacLeod Our lovely sponsors - PCBWay: fast turn PCBs, https://www.pcbway.com - Electro-Rent: https://www.electrorent.com - Keysight: test instruments: https://www.keysight.com - Samtec: connectors: https://www.samtec.com - R&D Microwaves: https://rdmicrowaves.com Get more technical info on the companion site: https://www.curiousmarc.com Contact info: https://www.youtube.com/curiousmarc/about 00:00 Recap of Part 1 01:45 Reverting to the original configuration 04:43 Schematics explanation 07:41 First regenerative divider 10:40 Magic "endless" phase shifter 12:46 Second divider not working 14:48 Debugging the divider 16:57 Tripler transistor weird fault 19:25 Our loopy circuit is cursed! 20:30 Second fault in the mixer? 23:20 It must be the transistor 24:10 It must be the tuning circuit 29:00 Maybe a biasing fault? 32:21 We got it, it's working 33:35 60 Hz reference repair 35:58 It's all repaired! 37:13 Atomic time, baby!
If I drink enough, my vision phases out the potato vision.
You were just early. Now it's up to 2160p.
Only with alcohol from potatoes
I watch everything on my phone, I barely noticed the potato vision.
@benjaminhanke79 I takes YouTube a while to render the higher res. If you just watched all was finished. NeillABliss was a bit hasty commenting on the quality.
@@bennylloyd-willner9667 Some of the video was shot out of focus with a comment over the top apologising for the "potato vision" (e.g. 11:18) - nothing to do with YouTube's processing.
Bad ancient tantalums?
Who would have thought!
Tantalizing repair.
I remember seeing an Amiga (late 80s/early 90s computer) for sale on Ebay where the vendor advertised that they had replaced ALL the capacitors as a matter of course!
Good old tantrum capacitors!
@@zh84 Sadly, this seems to be commonplace. Inevitably, it introduces new problems, as Adrian's Digital Basement found recently. He replaced the caps on a Mac SE/30 motherboard and in doing so accidentally bridged a 5V signal line to the 12V power rail. I've seen all sorts of other problems caused by recapping - reverse polarity, massively wrong value, under voltage spec etc.
This old RF jock thought 'bad caps" right away. If my semiconductors are good, every electrolytic/tantalum cap becomes the next suspect.
@@Zadster I have seen folk replace smoothing capacitors with much higher values "to make it better", only to find that the increased inrush current blows up the supply.
Marc: “This is going to be interesting.”
Yes. Yes it is. 👍
You know, that generation of engineers continues to astound me with what they could do with so few options. How one can create a sort of “minimalist complexity” still looks a bit like magic to me, wizardry I say.
We often don't appreciate how good we have it.
That tripler circuit (6:40) is at once crude and elegant: driving the thing so hard it distorts wildly then using the fact that a single ended circuit will have dominant odd order harmonics and picking off the third. So clever.
25:50 That's wild, the tripler is happily working as a quadrupler instead, thanks to its asymmetric single-transistor design evidently also generating plenty of even harmonics and not just the odd harmonics you'd get from nicely symmetrical clipping.
Oh, good catch! That's exactly what's happening.
Yes, I spotted that.
In the late 60s, I worked at a NASA STADAN station at Winkfield UK. We had a visit from the NASA calibration team. They flew around the world calibrating the test equipment. They also carried an atomic clock to check each station's clock.
Hardware from this era was beautiful. Really enjoying this series.
"Miracle dividers" - I couldn't agree more. That 4 transistor divider circuit is sheer analogue genius. Thank you for another very watchable episode.
Four boxes in the block diagram, four transistors. Those were the days.
New Curious Marc videos showing up in my feed always make my day!
I must be weird too : I enjoyed watching the various frequencies on the scope! 😮
… and a blurry schematic too!😂
37:56 I love that within the picture within the airplane they have a quad outlet box and three of the knockouts are knocked out on the side.
I have absolutely no justification but I want one after seeing this video. The engineering is gorgeous, and that display is a work of art.
Thanks for the continued awesome videos!
As a 60 year old mechanical engineer watching this, please, please, please clean the mechanical clock mechanism as per the service manual. Do it before it is too late. The tight tolerances of the bearings and the gearing are being abnormally worn every time you start the motor. The clue that it needs to be cleaned is that you must give the motor a very strong torque to start it spinning. You should be able to start the motor by a simple twist of the knurled handle between your thumb and index. Also HP would never have let such a noisy mechanism out the door. It should be whisper quiet.
We know. Clock is clean. There is a bad bearing in the mechanism. It's very difficult to change, haven't done it yet.
@@CuriousMarcso maybe you Need a watchmaker in your team. 😉
Dr, you have no idea how much I like the content on your channel; The analysis, the theory he uses makes his video super interesting. I thank you infinitely for all your effort and time in preparing each video. A cordial hug from Mexico
"If you follow the channel?" Of course I follow the channel!
Thanks Marc for doing these videos, like everyone's comments those HP engineers and manufacturing infrastructure were next level.
Great video. I love your explanations, demos and your test equipment. Quite a project!
Thanks! I am feasting on short clips from your old NASA videos too to look for Apollo comms equipment, I hope you don't mind...
Merci Marc , c'est quand meme fou de pouvoir s'amuser avec de tel appareils, quel chance !!!! un grand merci pour le partage c'est toujour un reel plaisir.
I'm a software engineer who considered being an electrical engineer when I was in high school in the 1970's. I like your methodical approach to debugging the various problems without making unwarranted assumptions. It is similar to how I debug a misbehaving program or OS kernel crash. It's a shame that so few professionals in our respective fields seem to have good debugging skills.
5:40am & curious Marc. Breakfast and a cup of tea….perfect end to the week
A few good beers and 40min of HP goodness repair. That was a nice evening. Thank Marc.
Nice work loop circuits always gave me a fit when I was working in electronics. Thanks for the video Marc.
Amazing bit of kit, transitional technologies are just so fascinating... love the germanium transistor mounts. Also, yours is the only channel which makes me want a noise blanker in the audio path
Perfect Friday morning content!
when working with transistors, grab'm by the DCs and the ACs will follow. Cool video, thanks.
Well said!
Merci Marc, another great video.
This is super! A lot of creative engineering from 196s
37:56 Interesting how they fastened the seatbelts! However, it looks like the equipment was travelling economy class. That's a bit of an insult to H.P. equipment. Should be first class all the way!
At least the cabin attendants gave them blankets and pillows.
You really do have the best toys.
Another great video. Please keep making them!
As beautiful as these constructions are, I'm grateful for the invention of PCBs when I see Marc chasing faults in this 3D labyrinth.
Salute Dr Paul Eisler
True, but nothing beats the smell of molten solder from the stone age 😊
PCBs and ICs are widely over-rated. You don't need them at all ;-)
That style of wet tantalum cap (TAA was a common type) were an absolute nightmare, they were used extensively in military equipment from the 70s and 80s and caused so many problems, the electrolyte could leak and, as it was sulphuric acid, highly corrosive. If they didn't leak, they often went short circuit and caught fire.
It's interesting that they reduced an oscillator to a mere ringing circuit. Some of the 80's game consoles included a crystal resonant circuit followed by a buffer amp for that same purpose, but this is the first time I've seen one that used feedback.
This device appeared in the recent Nova on PBS. Just for a few frames, but it was so obvious after having seen Part 1. Will try to get a link and offset for y'all.
Just watched it. Great episode on how quantum mechanics affects everyday life: https://www.pbs.org/wgbh/nova/video/decoding-the-universe-quantum/ . The HP 115BR appears briefly at 17:35, followed by the HP 5061A Caesium clock equipped with the later integrated Patek Phillipe divider and clock. Awesome science documentary, they are right up there with Veritasium. Or is it the other way around?
@@CuriousMarc Video not available for german users :(
Tantalum caps are great: two failure modes: short or open. They cannot deal with any reverse voltage, and the working voltage should never be exceeded.
Suspect the tantalums! Great job Marc. Love the point-to-point electronics, so easy to work on. That synchro motor is noisy... perhaps some Hamnmond tone generator oil is needed? I just bought some Kroil Microil, looks like the exact same thing... the mechanics sound a lot like a Hammond organ that wants oil!
Syncrho motor is fine, but there is a bad bearing in the clock mechanism. Replacing it is a bear though, you have to take all the gears out, so I haven't done that yet.
At Curious Mark's™ "We've Upped Our Quality. Now, Up Yours"...
Wow, that world tour to synchronize clocks sounds fascinating, it's History, significance and all. Is there a documentary or an interesting resource on the subject?
Another great one.
And they strapped it in a seat on the plane!😂 Well, it would be a more gentle flight than if it were bolted to the floor.
11:31 “Use your imagination to see this clearly” this would make an engineers life so much easier… 😂
Ah! The second you said "tantalum" it became clear. Unlike most capacitors, the failure mode of a tantalum cap is a short rather than an open circuit. It would have flooded your mixer with a bias, my guess saturating the transistor or introducing distortion at the very least.
On a side note, bad tantalum capacitors is a common cause of the failure of many early PC motherboards. When you measure a short between one of the power rails and ground before powering it up, guess what the culprit is 95% of the time.
(FYI... typing this on my HP laptop)
Testing if the coils are resonant - I half expected you to break out a GDO!
The "old" HP hardware is just beautifully designed and constructed, much nicer than the plastic stuff that's cranked out these days. It is somewhat odd that one needs to "kickstart" the device (open the rack?) every time?
Now we know what clock was used by the producers of ST:TOS that was next to Sulu when the ship was flung backwards through time on (I think) "The Naked Time".
Very cool
Now I know why my 5071A’s and Cs4000’s have the 100kHz output. I’d always wondered what that could possibly be useful for.
3:06 it's like electronic surgery.. Nurse... soldering iron! Stat!
@richardlincoln886 - 2024-11-08
Question - the bootstrap startup process: click the button, flick the motor
That's all inside the case - you have to dismantle that box every time you get a powercut/cycle the power on the clock?
Cheers.
@phuzz00 - 2024-11-08
The main workings seem to be on rails inside the box, so I think you undo the two big thumbscrews on each side (labelled 'open'), and slide it out just far enough to flick the switch and spin the motor. Then slide it back in and screw it shut.
I guess you're intended to leave it permanently powered along with the atomic clock.
@CuriousMarc - 2024-11-08
Yes you do have to open it up to restart it. But the clock is supposed to be powered by the crystal source, which has one internal and one external battery backup (that's why the input power is 24V DC and it has no mains plug). We'll demonstrate that when we run it with the HP 106B. The clock is useless anyhow as soon as it stops, you have to realign it to an atomic clock no matter what, so in practice that's not a concern. What would be terrible is that a non knowledgeable person could restart it easily and you would not notice that it had lost atomic traceable time.
@paulstubbs7678 - 2024-11-09
@@CuriousMarc Yes it should only be restart-able by men in white jackets (or whatever time boffins wear) with lots of letters after their names, front panel button proders (as in every day domestic clock restarters) need not apply for these jobs.
@MarcoTedaldi - 2024-11-10
@@paulstubbs7678 you forgot the fancy pants! :)
@anthonylovell2271 - 2024-11-10
@@MarcoTedaldi they come with the jackets 🧐