Those binding posts are very likely made of an alloy of Cu and Te. Reason: Corrosion resistance improvement without changing (much) the thermal EMF for copper - copper contacts.
Could be... it certainly didn't look like pure copper. I'm open for replacing them with better ones eventually, but all I found online were either cheap stuff or "doesn't fit" ones. And the existing ones were in pretty mangled condition, both plastic and metal part.
@@atkelar Check out the Pomona low EMF ones, type 3770-0 (black) and 3770-2 (red). And if you think those are expensive, have a look at the binding posts 2758 from LowThermal. 🙂
Nice job. I worked for Brown Bovari in London they had a controlled heat-humidity room on springs full of test equipment and standards we used to calibrate customer equipment with that looked just like this. great video 2x👍
I still am mad at that solution... when plenty of similar heatsinks around the same device use nice threaded inserts in the PCB, I don't see why they have gone that route here...
I think I see what they were trying to do with the nyloc nuts; trying to keep thermal expansion from loosening them. It isn't really the best way to do it, but it's easy and cheap, at least until you need to remove them. Poor Boots didn't like the hiss though XD
Sorry! The automatic dialog levelling thing in DaVinci Resolve also doesn't like the hiss... it removes it completely :D But at that time, I was really mad at these darn fasteners. No idea why... on the other board they used regular screws for the TO-3s...
I think it's clearly a matter of different designers; and probably also generations of them. The only functional difference would be that the amplifier board ones are "insulated" form the heat sink. But that's nothign a plastic sleeve couldn't do with a screw too.
I hope you mean the solid state ones, those “dipped” types. The hermetically sealed wet ones almost never fail, and are what NASA has trusted for ages in their space missions.
The scraper is a double-ended model: plastic on one, metal on the other side. Can't recall where I got it, it's been in my workshop for ages... but I think this and the current tube radio project are the first ones where I use it on video.
It might have been some special material indeed, but I'm not sure if pure copper... that I would see as more red than what these were; in natural light, they seemed a bit on the yellow side, hence my estimation that it was brass. For all of my life, they looked exactly like worn down brass ones that once had been covered with nickel or similar.
Weird a 555 with RC to create a 60Hz signal. The precision of the power grid is far better than than in general around than 1% and usually better than 0.5% in short term, more than that make the grid unstable to sync. That transistor with a ferrite bead in one leg seems to me a troubleshoot after the project. I bey it is on the base.
Typically the power net is operated with a long term accuracy as good as the time standard broadcasts provide. But the turbines/generators are allowed to “slip” a little during the high demand times and then they are “catching up” during the lower demand times.
@@InssiAjaton So small changes in frequency at bursts...and good long term. I see. I saw graphs of that and this 0.5% are the peaks you see. So on average it is far better then. I intended to measure myself with high precision. But I never had the courage to buy a GPS disciplined oscillator or even a Rubidium standard...maybe one day. They take ages to come and I am not sure of their precision as they come from China. With a good reference my scope will do all the data capture for me.
I wrote what I found out about it in the description; It seems a bit "grown" over multiple generations and instruments that share components. In this unit, the sole purpose of it is to provide a delay for the CPU reset pulse. Crazy but true. The signal doesn't get picked up by any other PCBs as far s I can tell.
Essentially, yes. I do have paper-towel like sheets (whiteboard whipes) that are good to run between the contacts. The same ones I use for the push buttons. But that's a bit fiddly with the tiny contscts, so I didn't catch it on camera.
Were those metal body axial caps new old stock, or does some manufacturer actually make them still? If the latter, I'm interested to know the manufacturer and/or the series name.
I found them on digikey, filtered by "axial" and "available" and looking at the pictures. I think it's the original Sprague(sp?) still. Don't know if they are still made; through hole components are on the way out, and axial components even more so...
@@atkelar Ahh, the digital lock-opening device website. Thanks for the tip, I've been looking for "vintage look" caps for a project for a while, so I'll check them out. I usually try to buy from the silicon-based supplier, since they have a warehouse here in Australia, or the mouse-based supplier since I usually find them cheaper. I'm honestly surprised they still make that style of case. I've bought other brands of axial caps before and later received an email saying that series was made end of life, so they're definitely on the way out.
Digikey was the first international provider I got recommended; not cheap, but usually quite fast in their delivery, so I'm sticking with them for rare but new components. Speaking of Australia, I'm experiencing problems the other way 'round... apparently, the Australian Postal service thinks they are not allowed to send electronics to Austria and keep returning my stuff... x.x
@@atkelar Sorry to hear that. I know how that feels, I've had my share of packages returned for no apparent reason. Unfortunately I've only sent packages internationally a couple of times and never had a problem, so I have no idea why they would do that or have any suggestions for avoiding it in the future.
The majority of the work is done though: most of the other PCBs only had one or three electrolytics at most. I'm keeping part three mostly to the troubleshooting part. Thre's going to be a bit of flip chart explanation. I'm still happy to have located and fixed the fault, when the previous owner clearly was capable and has given up.
I would love to see a comparison of heat-sink efficiencies. Anyone ever seen one? Lots of paste, not much paste. Silpad(?) with and without paste. Mylar spacer with/without paste. When I was taught - it was just enough paste to leave a cloudy film since it's "just filling microscopic variations" according to my instructors. Then I see other people that gloop it on like they're pouring cream on strawberries and everything in between. I wonder who is right, or if it just doesn't really matter. On a retro level. CPU paste/liquid metal etc. are probably a different animal entirely that I'm not personally bothered about.
Not sure if I have a comparison ready; but the gist of it is - according to my school days - that the thermal transfer between the two surfaces needs to be optimized. Metal planes will never be smooth and parallel, so there's always some air trapped between. This is what thermal paste is supposed to fill. So in my book, as little as possible is perfect. Just to "replace the air" because it conducts heat much better than air. Now the pads (sil[icone] I think) and the mylar ones are electrical insulators mostly, while being "OK" thermla conductors. They are only put in, when the device surface shouldn't electrically contact the heat sink. For Mylar, since it's also a hard material, I think everybdoy recommends a (non-conductive!) thermal paste too. For sil pads, I heard they don't need paste; though I think a very thin layer can't hurt, especially with old, not so flexible ones.
Hmmm... that timestamp is in the outtake... but I double checked: the amplifier board is solderd; one joint looks a bit odd in the video and the edit is done before all wires are soldered, as evident by some of them sticking out still. Whenever possible, I clip the leads after the soldering, so I don't forget any ^^
@@atkelar I'm worried a bit about the bottom connection of the blue capacitor, soldered at 04:01. Is this the same one you guys are checking up on? It looks a bit... unconnected? One of the transformer caps that was only accessible from the top, so no clipping after soldering :/
The video makes the fresh solder joints - with their bright reflections - sometimes look like there's a bit missing; especially when comparing to the older, dull joints. But since these caps were only accessible from one side, I did peek in with a magnifier to check if the solder penetrated all the way through the via. These "up close" inspections are impossible to film though. Unless I eventually get some tiny close up lens for a decent camera. But the cheap "USB microscope" that I have is good for live streaming, but a.: the picture quality is not up to par with the other cameras I use and b.: it's still too big for this case 😅 - I was looking into magnificatino goggles with built in/attached close up cameras but these are similar either toys or "call us for a quote" type of equipment.
Oh, those. That's basically copper with tin coating. It predates the solder mask that is printed on these days and provides the "color" of the PCBs. The painted ones are less prone to rusting. Also, this isn't really good for surface mounted parts. If there's any other reason, I'd also want to know, but I think these are already plenty for the industry to not use the tin coated ones anymore.
