Modern Fails: Newall C80 DRO repair
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- เผยแพร่เมื่อ 11 ก.ย. 2024
- My expensive lathe digital readout just failed, and Newall does not want to repair it! So, we reverse engineer it, and find out that the proprietary principle of operation is absolutely genius, involving ball bearings and magnetics, with a readout precision of better than 10 microns. And the fault is quite unexpected. Hint: not a capacitor.
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That first version of the reverse engineered schematic is worth a print on a t-shirt 👍
I'd buy that.
I would buy that.
take my money
You went down the rabbit hole and came out with the rabbit and hat , well done. this should help other owners too.
Beautiful clean Sensor Signal, well deserved patent as it is even mechanical pretty accurate and still simple to process
Hello Marc! I'm the national sales manager for Emco (and I'm an avid follower of your channel) if you will ever need spares for your lathe, just let me know!
@@federicos8504 Woohoo! I love that lathe. Thanks for posting here!
The way that quadrature signal is derived from the ball bearings is amazing! Operating at 1kHz you should be able to diagnose if the signal input is working by putting a stethoscope on the transducer and listening for the 1kHz tone!
Tracking down, reading and understanding a patent, to end up replacing a memory chip ;-)
Fascinating video!! Thank you.
Good on you for using that clue, of losing configuration. That sure was a rabbit hole.
I think I got lucky twice on that repair…
@@CuriousMarc You sure did, the epic HP repair from a few years ago was caused by a similar short and it took months.
Would be interesting to read back the old chip and see if it's whole chip or just a stuck bit failure. Regardless, I would have assumed they store a checksum of sorts to prevent bizarre failures like this. Apparently not. Great repair as usual!
I would also like to see this. I've repaired a number of C80 DROs and the most common problem was failed keypads where the units would no longer register button presses.
@curiousmarc if your keypad ever fails, I can send you a custom PCB replacement. It's a bit of work to get the old flexible one out but the replacement works very well.
Another issue I had with two units, similar to what is shown in this video, where one or more axis would show corrupted data, was caused by issues with one of the socketed ICs making bad contact. Usually you could apply pressure to the affected one or slightly bend the board and it would fix it. Re-socketing each IC and cleaning the pins would fix it long term, even though they showed no signs of corrosion. I'd inspect the solder joints on the digital board as well and reflow any that seemed even a little off but I don't think it was a solder joint problem.
@@ourplesoop
I have a C 80 that is losing its accuracy, I have reversed the heads and originally it was short by .020 in. but after reversing it it’s long by .005 in.
Do you think by re-setting ships this may help this problem?
So, they made a linear resolver. Given that the resolver was the 'go to' rotary position encoder of the 70s (when first Newell patent was filed) it sort of makes sense they were thinking along those lines. The execution is brilliant. Makes me wonder about the transducers reading the bearings. Perhaps they are just mono compact cassette heads or something similar purpose made.
What’s really clever is the adaptive re-use of the ball bearings, which by necessity all have to be manufactured to super-low tolerances, and any variance with one is going to be averaged out.
I was also contemplating the nature of the odd failure. Since it displayed 'Start' on the top DRO (probably from ROM) and gibberish on the lower (instead of versions #), I wonder if it was trying to read a delimited string from the FRAM and getting back garbage which just happened to never be the delimiter.
I can't believe how good of an idea it was to use ball bearings - that's basically an off the shelf part you can get in a tolerance of +/-0.00005". So you don't need to do much precision work yourself; no printing tiny optical scales onto glass, etc.
That’s the idea, affordable stable precision that’s oblivious to dirt and oil. To cap it off they have a pressure adjusting screw at the end of the rod so the total length of the ball stack is exact. It’s factory adjusted of course.
There is a replacement type of the FRAM FM24C64B, if the WP Pin (write protection) is not used, the replacement is 1:1 compatible. If WP is used, then there are some Changes! B Type memory is fully write protected, the old type is partialy write protected only 1800h to 1FFFh is protected. If this feature is used, then FW changes must be done, in this case not possible.
Thanks for the tip!
Two geniuses at play here, the person who designed this and you for being able to figure out how it worked.
Those scales are very similar in operation to the Sony Magna-Syn scales that we still use on the larger CNC machines. Sony always provided a "converter box" to convert the "magnetic" signals to conventional TTL square wave output or the newer 1 volt peak-to-peak sine wave to allow us to connect them to any industry standard controller. Merci pour le video Jean-Marc !!!
Nothing i enjoy more than watching along and pretending i understand what's going on 😆... One of the few content creators i don't skip through the adverts because you deserve every penny of ad revenue.
22:50 Thank you so much for measuring the size of the balls, I was trying to eyeball it earlier in the video and you saved me from having to go back and check
A great comeback from an easy-to-make mistake. Public service achieved! Thanks for including the probe slip story. It happens so easily and can be so devastating. It's one of the most frustrating things to break something during an attempt at fixing it. I'm glad you had a replacement chip and that the FPGA was OK.
That is so cool! Thank you for explaining how this worked. You know, funny thing, but I did that same stupid thing on a board I was working on last week... I bridged +12V to the logic +5V and blew up the Arduino microcontroller up. I experienced the horror the moment you realized what happened... I'm glad you got lucky and didn't have more damage, or needed that PLA chip.
It’s part of the occupation hazards…
A former employer was manufacturing an evaluation boards for their processor cores. The CPU was on a card. Sometimes it was a hardcore (rarely), sometimes a softcore in a big ass FPGA (most common) or two for the most complex designs. We're talking about the biggest FPGAs money could buy which were expensive so dual FPGA variants were rare. The evaluation board was mostly a glorified I/O board, flash, voltage converters, what not. So there was little motivation to upgrade or in fact do any modification to board. The core of the I/O was an Intel PIIX. Eventually Intel cancelled that product line. No problem, we had ample stock. Then eventually RoHS came to truly finish of the board. The PIIX was not available in a RoHS variant, our stock was running low. The board could probably have lived another five or ten years as a meaningful evaluation platform with good software support.
My friend's company had to redesign one of their remote sensor boards when RoHS came in because the solar/battery controller chip wasn't available as lead free. The irony is that the battery was a YUASA sealed lead-acid battery which had considerably more lead than that tiny chip ever would, but "them's the rulez".
@@TheOwlman RoHS still makes sense. People have learned to recycle or dispose of lead-acid batteries properly. Here in Germany there's a significant refund on car batteries, 20€ I think it is. But electronics may still end up getting tossed out with household or other waste. And only too many amateurs or small shops only doing occasional solder work don't have proper ventilation to protect workers from lead fumes.
@@ralfbaechle I cannot disagree, millions of chips with a tiny bit of lead is still a lot of lead, it is just the irony of several kilos of it no longer being able to be charged by a chip with milligrams that struck me. It more shines a light on the past poor performance of electronics recycling that makes me hope they have improved in the last 30 years. The rise of lithium technology concerns me - I seriously doubt that will be as efficiently recycled as lead-acid until such time as either shortages or legislation make it happen. In the UK at least, the number of problems with fires from disposable vapes in domestic rubbish in on the rise; in Lincolnshire we have had a fire at a refuse facility in the last few days and a bin lorry caught fire out in the road last year, both the result of vapes.
And still there is a very toxic organic lead compound added to the fuel for airplane piston engines. Exhaust gets spilled as aerosol over our heads. How delicious.
I am a bit unsure about ROHS. Devices using Lead-free solder seem to have a shorter lifespan.
Alkaline batteries without added mercury will unavoidably leak and kill the device around them beyond repair, leading to even more e-waste. Batteries can even leak before they are electrically exhausted. So it's hard to notice.
If I remember correctly, there was a short time in the 1980s when alkaline batteries had become affordable and not leaking before the ban of mercury. Mercury stops a chemical process that generates gas inside the battery. Gas pressure builds up and causes the leak of potassium hydroxide solution.
Marc! I feel your pain... I was repairing an audio mixer, and I plugged in a molex power supply plug off by one terminal, and shorted the +48 phantom power input to the +15 volt rail.
This of course blew up every single Op-Amp on the board for every channel, every bus, and every output!! That really hurt!
Even reading about this hurts...
A lot of "penalty" hours with that desk 😅
Ain’t that annoying when that happens. But it is our lot. We repairers are made to suffer from blowing up our own parts.
You should go out a buy a book of Powerball tickets! You are one lucky fellow! Two bad chips, after sending 15 volts into the 5 volt rail!!!! Excellent repair as always, nicely done Marc!
Again, thanks for showing your mistakes as well. We learn as much from these as from your (often incredible) successes.
This was a particularly satisfying repair. I enjoyed seeing it on a modern piece of equipment because it's easier to follow the test process on a circuit board than on something with a tangle of wires (although watching those get untangled is its own form of entertainment!)
I wonder who first had the idea for that ball bearing sensor? Simple but very clever!
Maybe it's Newall? I don't see any prior art citation in the British patent.
Not the same but perhaps inspiration, I have a height gauge for a surface plate that uses a set of stacked 1" balls and a 1" micrometer to accurately measure up to 24", APE microball
Brilliant work, Marc, as usual. That method of precision linear measurement is so elegant in its simplicity. I would suspect that the ball bearings are dimensionally very high precision parts, being about as close to a consistent 10mm diameter. I bet linear position sensor assembly is pretty expensive by itself, even though it's a relatively simple assembly. I would have never guessed that they would have used a FRAM device, but perhaps they were thinking about long-life versus SRAM devices with a built-in battery, like those used for configuration memory on old Sun workstations and servers. When the battery goes flat, they won't boot. Replacing the device doesn't fix the problem, either. You have to go through manual processing of reloading the base configuration parameters using the built-in Forth interpreter. Fortunately, it was much less cumbersome to reset the config once the FRAM device was replaced. FRAM was a pretty neat technology, but as this case shows, it simply couldn't live up to the longevity of good old-fashioned magnetic core memory. The core memory in some of my old calculators from the mid-1960's are still working just as well today as when they were new. I always love watching your videos, and this one was especially fun to watch as you reasoned your way through figuring out how it worked. Kudos! Thank you for doing your videos. They are a great example of the true goodness that the Internet can offer.
I always wondered how those linear measurement tracks work. Thanks for that
As usual, I’m in awe of the combination of comprehension and execution…wow! 👍👍
It would be interesting to test the FRAM chip outside, and see if it is a single bit failure, all of it, or you just get random bits out of it.
Marc: _“…bad Chinese electrolytic _*_crapacitors…_*_ “_
Me: _That’s what I heard, right…?_ 😂
Yes. A crapacitor. That's what they are called, right?
I didn't know ferroelectric chips exist. As I understand it's not an serial EEPROM. I would love to see a detailed explanation on these with elevator music.
It’s called an FRAM. It’s essentially a modern version of core memory.
The remarkable bit is not what they do - plenty of chips can store data while not powered in various ways - but how they do it: normal chips tend to be rated for anything between a thousand and a hundred thousand writes (to the same bit), which plenty of applications can wear out rather quickly if not minding how often they write. Well, these are rated for TEN BILLION writes, which is a rather different ballgame (and all the more weird to see them fail).
Actually, I'm beginning to wonder whether this thing didn't fail exactly because it WASN'T a real ferro chip just a pinout-compatible conventional fake which couldn't take being used as if it was the real thing...
Current production is cheap and easily available. Almost went with it for a small project of mine. Eventually decided to use PSRAM instead lol. Most are made to be pin-compatible with (I2C or SPI) EEPROMs I believe, and should be about as easy to use.
@@alexsuykov That's why I'm suspecting a possible fake - they could have dropped anything else in there and it would have just worked (until it failed a write)
Maybe evilmonkeyzdesign could decap it for a look see look see.
So Ken is not the only wizard of reverse engineering! I assume most failures of this unit will be this chip... the weak point shows itself... way to go Marc.... I salute you.
I’m a baby reverse engineer compared to what Master Ken and TubeTime can do!
@@CuriousMarcNone of us were born knowing this stuff, gotta start somewhere!
@@CuriousMarc Do Patreons get the diagram? That would be nice. Or better yet, release it into the wild!
@@scowell Sure! I can make it available on Patreon. Eventually, when I get to it, it'll be released on my web site.
It is understandable that they didn't want their tech to be put in the public domain, but they didn't count on @CuriousMarc being their adversary. It is an example of where a better strategy for keeping a secret is helping the guy who doesn't know the secret but is clever enough to figure it out anyway; would he have made this video if the vendor provided the fix? That is a question for Marc.
As someone with little clue about electronics it is fascinating how you could reverse engineer it. Also how the Lathe uses ball bearings instead of a decoder is amazing. Thank you for the great video.
Nicely done! I too was thinking a bad crapacitor, but I would have never guessed the fault would be in the FRAM.
Some embedded devices fall into a "crazy mode" if some internal test has failed, in this case, the non-volatile memory. The device was deliberately generating random numbers. I've seen this before with a thermostat that briefly got a bad voltage. The LCD segments started flashing randomly. In my case, simply resetting the device solved the problem. You took the long way around but we learned more about how it really works, so I guess that made it worthwhile.
I always wondered how they worked, such a simple but genius way of doing it! Fabulous and thank you.
So the overall accuracy is tied to the accuracy of a bearing diameter, and subsequent error that accumulates as they are stacked. Fascinating. I suppose a sphere may be easier to manufacture to a precise tolerance, possibly by tumbling (honing) in a media.
I'm impress, the vernier thing with the phases reading is a very clever idea. And that type of memory i never know about it.
Great episode.
And I am even more astonished when I see that the people who comment know more about the topics presented than I do. I am truly in the right place.
Well there you go. I learned a very interesting way to do meteorology today.
Thanks for taking up this noble cause and succeeding ! ... and ... I appreciate the learning.
Ball bearings make sense, given the accuracy to which they are ground and their price/availability.
This sounds very similar to the GE Accupins system used on 60's CNC machines. If you search "way back ge accupins" you'll find a cnczone post discussing how they're driven. It has links to images; the image dir is public and has more pics.
I used to have a real old electronics Guru named Ed Jeffries (RIP, Buddy) who was as awesome as you are Marc. Now I don't awe easily but - like Ed used to do - You awe the shit out out of me Marc !
That circuit is a very eloquent and brilliant design. Great reverse engineering Marc!
An F-RAM chip lasting "only" 20 years is still a good quality design. Especially given that reads are "destructive", e.g. the values need to be written back after reading. The whole electronics box is quite a feat of engineering. It still workd. despite its usual operating environment (vibration, metal dust, chemically aggresive oils, big inductive loads on the same power cable...)
Thank you for clearing that mystery up for me!
Have been very curious about how those sensor works for a long time! Did my education on CNC-machines in the mid 90's storing the programs on paper tape!
Excellent repair. 👌 Machine shop equipment seems to be in a world of their own. Very clever design ideas. Thank you for a great step-by-step video.
those switched capacitor linear low pass filters are super cool! I've used an 8th order Butterworth lowpass filter in some A/D and D/A research projects! They are basically a brick wall filter at the cutoff frequency!
Yup, learned something (several things) fun about electronics again from Prof Marc.
Not such a far shot from a DSKY, haha. Nice fix - good luck with the machine!
Come to think of it, it *does* look like a DSKY! Wouldn’t it be fun to make a replacement that looks exactly like one 😊
@@CuriousMarc ...where you need to enter numeric nouns and verbs to control the machine!
Merci for the video! I am now a little more appreciative of my Fanuc controllers at work.
2:45 We need a group that that make obsolete and jellybean parts to combat the shady Chinese obsolete component seller and continu Through-hole parts.
If not make , ethically recycle obsolete parts from old equipment.
Newark Electronics to the rescue!
Yep that was cool. Funny how small innovations are built on over and over again. The good old Schmitt trigger comes up over and over again.;)
It's easy when you understand and know what you're doing!
glad not to be the only one doing dumb mistake during fault debug
You are a genius! I very much like your attitude, your explanations and your superb videos. Pulled in by your AGC series once. Now a big fan. Well done. Again.
I guess the FPGA is just a kind of capture / compare timer. Today one could use the integrated micro controller peripherals to measure the phase precisely. Could be a nice hobby project.
Great video! Very cool how the sensor works. Thanks!
Outstanding sleuthing, and oh such a satisfying solution! You earned yourself a nice glass of scotch in your easy chair for this one!
Very surprised by an FRAM fail, i was under the impression they were very reliable long term. Maybe not actually a failure of the underlying tech but some other common manufacturing defect that is only coming to light 20+ years down the line?
I'm surprised too. I bet they used a FRAM instead of an EEPROM for reliability. Or maybe the FPGA needs to write to it frequently?
That was particularly interesting, thanks dude!
Thank you Marc, great trouble shooting video. This is an interesting tale. The decision one makes depends on the value of time. If the solution of replacing the chip were unknown, it would cost thousands of Dollars of an engineer’s time to find the fix, which luckily existed. Meanwhile if this were a production shop many thousands of Dollars of production would be lost while the equipment is down waiting for a fix. Replacing of the readout unit would be a bargain at only 1200 Dollars in the production shop case.
Now that it is known that the fix is an inexpensive though possibly difficult to source memory chip, the answer for people who follow Marc’s footsteps is to fix rather than to replace.
Much hinges on the availability of the obsolete memory chip. Those memory chips were $5 on eBay before this video went live; I’ll bet they suddenly got more expensive.
Amazing technology. Very ingenious! Thanks
A VERY good find. Congratulations!
thank you for solving the mystery of what size ball bearings are inside the sensor 😂
"electrolytic Crapacitors". They were new for me😅
Fantastic video. My favourite so far!
It’s good idea that you put IC socket there❤
Wow! It wasn't a dead battery on a Dallas battery backed RAM chip!?
Sounds very much like the linear version of a resolver.
Exactly! You can play the same trick with a resolver, combine the two outputs, and get a 360 continuous phase shifter. As a coincidence I just repaired an odd piece of HP equipment that does just that!
It is not core memory and wears out.
It probably stores the integer ball offset in the non volatile memory. The unit is probably saving it continuously because the FRAM allows for fast writes and reads. As an potential bit of software laziness it probably reads the value from it before displaying the results which is a BAD THING to do with FRAM that has FINITE READ (and write) cycles before failure and should only be used to store data that is non-volatile and not a working variable.
If you can check the read and write pins on the FRAM to confirm that it is accessing it continuously it will explain why many fail with that built in obsolescence design.
Some fixes:
Turn the unit off when not at the machine (It does remember the position anyway).
Another possibility is to make an add on board that will prevent memory access when it is not moving.
Keep a stock of 8pin sockets and FRAM chips on hand.
When it was broken, I wonder if that "random" number output was actually the board executing a ROM dump
Absolutely fascinating! thankyou Marc
Using ball bearings as a reference length is super interesting.
1960s equipment that works without an issue 60 years later, and now our modern electronics ;) I live in Berlin, in a building from 1880. The basement is timeless, but they had to install device to combat Legionella infestation in the hot water system. Those are hyper digital, bright LED devices that look like a space ship. I am sure that in 3 year a cap will burn through, or a voltage regulator will fail, from the useless LEDs alone, while the rest of the house will be good for another 100 years.
I bet whoever at Newall decided to stop servicing these DRO's never anticipated it'd result in their technology being reverse engineered by the guy who reverse engineers and repairs the Apollo guidance system for fun!
My dad has a Newall DRO on his miller, which he bought new and has only ever had light duty, home use for model engineering, yet it's had 2 encoders fail. Disappointing given how expensive they are. I remember looking for info about how they worked when the 1st failed, not because I had any chance of repairing anything, just because I line to read about how stuff works. The balls in my dad's must be a lot smaller than 10mm, as they're in tiny tubes (carbon fibre, I think), about 5mm diameter.
I love that Marc has the same definition of "modern" as me. 2000 "modern". 25 years is "modern" :P
And I don't see why a memory chip for basic settings glitches everything? Maybe because the settings sets zeros and offsets for measurements... ?
And I'm surprise there is no self test mode of every chips on the board, at boot up, on such an expensive piece of kit, with a clear error message to prevent using a machine that displays garbage. I have 40 years old pinball machines that tells me when the RAM is dead with a simple LED, and prevent the machine to start as a fail-safe feature.
(....rewiring my brain...)
Ha well, answer is : it's *not old enough* to have self test modes and schematics availability...
I suspect “modern” is have an analogue board for basic sensing and let a cheep off the shelf processor do the computation.
@@francesconicoletti2547 modern means "obfuscated design and lack of schematics or service manual"
I agree. The real "Fault" is poor firmware, that didn't include a checksum/CRC of the FRAM, and print a diagnostic on failure. This is nothing new. I had to do this on my first exposure to EEPROM in 1986, which had an endurance limit of about 1000 cycles. The system stored settings in blocks, and each block included a count of how many times it had been written, and a link to the next block in the chain. Once the "current block" approached a limit, it was saved with a link to the next "current block", and never written again. Then the cycle repeated with the next "current block". Working in this manner, the system would have been capable of millions of write cycles, as endurance was spread over the entire part. All coded in 8031 ASM, a brother of the 8051!
Thanks Marc.
Great video Marc!
An interesting principle, though I am confused on one thing. Presumably, as the balls are a fixed spacing apart and repeat regularly along the sensor rail, does this mean the sensor can't actually tell which ball it is over, just its relative position as compared to a ball? So to measure longer distances you just have to keep reading often enough to know you haven't skipped over, and keep track of it incrementally?
From what i have seen on machining channels you generally zero in on the part in place. You touch off on the actual part as it's in de spindle and then call that 0.
Absolute positioning in relation to the lathe is not relevant unless you would machine thousands of exact part but that would be more of a CNC job (i guess). Missing balls is probably not possible as you would have to go really fast with the carriage to skip over a ball.
You are right, it needs to count as the balls go. However there is more trickery than I told there. I think there are some coded magnets hidden in there that digitally encode absolute position.
Typically only CNC machines use absolute positioning, and even then, they don't typically use absolute position encoders. They use relative sensors, and a fixed home switch. To eliminate the accuracy and repeatability of the switch, the switch itself isn't "home", it just tells the machine it's in the "vicinity" of home. Once the switch is hit, then it waits for the reference pulse on the servo encoder (once per rotation of the servo motor) + some number of encoder pulses beyond that (which is settable in parameters so the absolute home position is adjustable), and then THAT is "machine reference position". Beyond that will be another physical switch which indicates OverTravel and shuts the servo drives down in case of something going beyond where it should be to prevent damage to the positioning ballscrew/ballnut. Once that home position is reached, all other movement is relative to that, and it's just counting encoder pulses. On a manual lathe, it's basically the same, but there's no fixed "home" position - you're redefining 0 wherever it needs to be in both axes based on measurements.
@@CuriousMarc Try moving the lathe while the DRO is powered off. Does it register position changes even while powered down? 🤔
That was incredible luck with that atmel
Well done as always
What a goofy repair. Reminds me of HP laptops that scramble their bios contents on every power cycle and they eventually kill the memory cells in the chip.
Side note, I'm so glad the overvoltage repair was simpler than the HP 9825 repair saga!
Me too! I had a bad flashback...
Thanks Marc for the amazingly interesting educating entertaining video !!!
Sure beats a hslf hour watching a "reality" show! This is reality stripped down to its undershorts!
One crazy chip, it would be an interesting device for a retro inspired computer build, I mean anything related to core memory has to have some retro cred.
Trying to prove to myself how the phase shifted signal is produced... I noticed that the 4 sine waves would sum up to 0 if it weren't for the weighting done by the bearings. Haven't quite done it yet, but 2*sqrt(1-(x-2)floor((x+1)/2))^2) produces the inductance pattern (balls)
Got something to half-way at least demonstrate the phase-shift effect on desmos, zifewrpg5j is the ID. I've made some other guesses at the transfer function, and it seems to produce a phase shifting affect, as long as it's periodic and 'humpy' -- just sin(x) seems to work too -- but everything I've tried is non-linear w.r.t position and also has large amplitude changes. One interesting thing is that the parameters may need to be tuned to avoid amplitude inversions... I imagine that would make the FPGA's job harder.
That's a mad hand written schematic!
The ball bearing concept is intense. Hope Newall doesn't send a cease to exist letter for talking about their design. Another great explanation video! I'm no dummy but you make even the most complicated concepts easy to understand.
All the info Marc got was from their patents, which are in the public domain
@@phuzz00 Yeah, he mentioned that. Even though it is public domain, I just figured most people wouldn't encounter the information without digging.
Newall is fine. The info on the patent is public. And there must be a lot of secret sauce to make the sensor head work in practice (and give absolute measurements - I have not even talked about that part!).
Interesting sight into a laboratory I had not yet seen.
Would be interesting to put the memory chip in a demagnetiser to see if it could be fixed
great repair 😁
excellent
The electronics version of for the loss of a nail the shoe was lost etc.
I'm feeling oddly patriotic after learning about the ball-bearing method of metrology. I wonder whether whoever got the UK patent made any money out of it.
Wow. I'd love an elevator music version of how that FRAM works, since it doesn't seem like EEPROM I'm used to. Also, I do get worried the more modern unserviceable tech we get with no manuals and eventually no spare parts available we're gonna need more and more general "reverse engineering" skills. Bit of a worry though buying parts of unknown quality though since I've certainly ended up with fakes before.
Very nice repair, and great explanation of the mechanism. As far as the short, all I can say is that I really really despise those fat probe tips with the oversize ground ring just waiting to short something in the general vicinity. Give me a proper skinny probe tip any day. Lucky you only lost the CPU.
Excellent explanation! Always great to see what tricks can be used to get precision for an "affordable" price!
Also, did you by chance find a modern version of the FRAM chip? Maybe there's a manufacturer out there making a pin compatible replacement so people don't have to rely on salvaged parts :)
Didn't try. They were cheap and plentiful on eBay, so I just bought the exact replacement.
That was great.
They must spend a bit of money on those ball bearings to get very close tolerances. Over a long sensor these could add up to a lot. I wonder if they select them, or match them in sets to lock in some error offsetting within the group.
Very interesting but soooooo super simple way of measuring 😊 Thank you very much Marc for this fantastic video once again.
Love it , as always😎
This reminds me of the way Avionics Navigation system "VOR" modulation worked to determine bearing
Switched-capacitor filters are not "digital", though they are discrete time.
I love your work, starting from reverse engineering (wish i could do similar things) and also figuring out how things work. Did not expect such a solution. Still one question is open to me, it measures only one time the 10mm and then over and over right? Means it is counting then for ongoing measures.
great job!