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- เผยแพร่เมื่อ 7 พ.ย. 2012
- How do glass ultrasonic acoustic delay lines work? The kind used in PAL video recorders.
This is Part 3 of the Sony CCD Video 8 Camcorder Teardown.
PART 1: • EEVblog #375 - Sony Vi...
PART 2: • EEVblog #380 - Sony CC...
Service Manual: www.freeservice...
Forum Topic: www.eevblog.com...
Delay line info:
www.morgantechn... (chapter 6.9)
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Didn't see any comments about the transducers on the edge of the glass so I'll comment. If you look closely where the bond-wires are connected, you will see two conductive layers stacked on top of each other. Between them is a piezo film. The piezo material is sandwiched between the conductors which are stepped to expose them as pads for the bonding wires. When the conductive layers are energized they cause the piezo film between them to flex. This flexing sets up a vibration in the glass plate's edge that propagates down the acoustic waveguide. The features bonded to the face of the glass plate as Dave describes form the acoustic path. When the wave-front hits the far end of the waveguide it flexes the receiving transducer (which to my eye) appears to be identical to the transmitting side. The glass itself is not piezo material.
The camea's delay line is used to increase horizontal resolution. Delayed video is subtracted from undelayed video and the difference is amplified and added back to the undelayed video. Other cameras use 1H delays to increase vertical resolution.
The VCR uses the delay line for dropout compensation. When the signal off the tape dropped below a usable level, the previous 2 lines of video could be switched in place of the bad video. Most tape dropouts are much shorter than 2 lines.
The 2 inch quad VTR's used delay lines which were approx 6 inch (150mm) rods of quartz.
Richard Smith I'm not sure what the "aura"is that you're referring to.
A dropout compensator improves the picture. It goes unnoticed unless there is a multi line dropout from tape damage. Then it fills in the last good line repeatedly, but each line gets a fuzzier. Since the original content is gone anyway, that isn't really a bad thing.
Richard Smith Well VHS and Beta were pretty bad to begin with, so multi generation copies will suffer. The color is downshifted from 3.58Mhz for NTSC to 622Khz and recorded as AM. The Y(luminance) was FM, which is better, but only about 3Mhz bandwidth at best. Plus, each time you separate the Y+C, you get more loss.
The tape tension in a VCR is pretty low, if there's any stretching it would happen in storage. You would get a linear tracking error from top to bottom of the picture. Most tracking problems are due to tape guide misalignment, though. The big danger for old tapes is when the oxide layer starts shedding.
Beta format is full NTSC video bandwidth (5.5 MHz), capable of recording and reproducing studio-quality video. VHS is only 3.4 MHz bandwidth, but the untrained eye, i.e., most consumers, can't tell the difference. As a result, the lower-cost VHS format won the market.
I love those old service manuals. Back in the days when things were built to be repaired..
1985 was a great year, and that service manual is a thing of beauty.
On the CCD, there's obviously the color bayer pattern, but above this there is a layer of micro-lensed material. This serves a couple of potential purposes, it can act as an anti-alias filter to mitigate Moire patterns, this means it is a spatial domain Nyquist frequency pass band filter for light (although it won't be as soft as it needs to be for marketing reasons) Bandwidth in the spatial domain here is limited by the CCD pixel density. It also helps gather light into the photoreceptor wells to make the CCD more efficient. I suspect the optical effect you are seeing is refraction and internal reflection on this micro-lens layer.
Thank you very much, I know it's 10 years, yet that thumbnail helped me to find out.
Marvelous piece of engineering, and thanks for the explanation, I was fascinated when I had my self one, disassembling a TV (broken) was absolutely astonished then, as you showed the tranceducers I noticed them too but never thought conversion to sound and manipulation inside a circuitry was ever an option.
I did almost forgot untill today. Thankyou.
@22:01 I saw one of these glass delayers 30 years ago, and I never found out what it was. Today I'm celebrating this knowledge, thanks to you, buddy :)
Beautiful!
Yes, I wanted to do a follow-up video this one.
There's got to be some great learning to be had by looking at the waveforms there - more so having the gear and probing at the points, and correlating activities with the service manual. I am now eyeing up any vintage gear in our flat to try and find service manuals - though I doubt any will come close to that beauty.
Hi Dave, i was a Service Manual writer once at TELEFUNKEN Germany. It takes about 1 full month of work just to make a service manual for a CD player, when the schematics have already been done. It would certainly take 5 people 3 months to make this elaborated manual from that Sony cam.
Just came across this. Excellent video Dave, haven't seen one of those in over 30 years. Used to work at the Philips plant in Blackburn, UK some 30+ years ago there we made the glass delay lines for use in tv's, bring's back a lot of memories. Thanks......
Absolutely incredible! I was given a somewhat earlier black and white camcorder with a shoulder-strap recorder unit separate from the camera. Absolutely incredible piece of tech.
that remembers me of myself playing around with parts of a Telefunken 418A chassis, which i took off of a TV that couldn't wake up from standby anymore. I was able to get the service manual. I loved to understand how they got the telly running back then and what they claimed back then. Quote: "low power consumption in standby-mode (about 6W)". And later I even spoted the TV's problem (dead flyback-driving-transistor), but I didn't solve it then, because I totally torn that thing down already.
Absolutely wonderful peek into the inner workings! Your passion for how things work and teaching spirit are a great gift to all of us. Learning that a glass delay line device existed more than fulfilled my goal of learning something new everyday. Keep 'em coming!
The video is FM modulated on a carrier which is 4x or 8x subcarrier frequency. You can see the sync and blanking areas on the 'scope because the frequency response of the signal and/or the 'scope is not flat. The other terminals have a much weaker signal because there is a lot of loss in the delay line.
I absolutely love this channel!
I've seen those glass delay lines in all sorts of old equipment like VCRs and televisions. Been tearing stuff down for about 25+ years now! It's amazing seeing how stuff's changed.
I always wondered what the black resin patterns on the side of the crystal were, and always just assumed they were "standoffs" to stop the crystal touching the inside of the case.
For BetacamSP format where differential chrominance signals (Y-R, Y-B) were first compressed and then recorded in a time of one TV line, Sony used CCD as a buffer.
Every EE in PAL land should know this.
ahhhhh I remember finding these when I was scavenging flybacks and components out of old TVs as a kid. I thought they were some kind of high value precision resistor but couldnt figure out why youd need that in a TV, which of course you dont because theyre not. nice to finally know what they are.
Chapter 6.9, "PZT Delay Lines" of the "Piezoelectric Ceramic Properties and Applications" manual at Morgan Technical Ceramics has a good technical description of how these types of devices work.
I saw both of this delay lines on a Sony TV and I've always wondered what they were. Thanks for explaining :)
well, from what I could gather , Delay lines are a form of memory that does what it says in the tin, instills a delay into the data stream... By inducing a wave ( usually a compression wave ) into a media ( some of the really old delays were based on a physical wave in a tank of mercury) .
Wow, that's like a wave guide for transducer induced shock waves in quartz. Amazing!
Sony still makes great service manuals for their pro video gear. They also offer maintenance training in their CA and NJ facilities. I have been to 2 two-week courses, and the manuals for each filled three big binders. They are also available in searchable electronic format- thank goodness!
No such thing as the next level, just continuous improvement, I still lean new stuff every day after 30+ years of doing electronics. Read and hang out in a forum like the EEVblog forum and you'll learn a lot.
The filter is definitely a Bayer filter.
Pro NTSC cameras used glass(quartz) delay lines for the vertical detail circuit. The 168nS delay line is for horizontal aperture correction which is pretty much the same thing as horizontal detail. In detail circuits delayed and undelayed video are subtracted to create a signal which represents the high frequency components of the video. It is then added back to the video for a sharper picture.
VTRs used glass delay lines for dropout compensation.
back when things were designed to be serviced, instead of replaced.
I used to work for ICL Computers in the UK (now part of Siemans) from '89 to '91, and durng that time we went from replacing CRT assemblies and repairing keyboard key switches to WUS or Whole Unit Spares. I guess that was when we reached the disposable age...
To really check if the filter is polarizing (which I think is not), you should use a polarizer in the detection or the excitation. So, in front of the camera or in front of the eyepiece used for illumination.....
This video just blew my mind a wee bit. Being fairly young (30ish) and not having dealt with electronics much more than the small amateur tinkering with MCUs I do at home I had never seen this type of physical interaction between components before. Sending signals through a piece of glass/crystal to slow it down, man, that's (in lack of a better word) fucking cool. Sometimes it makes me sad how everything these days is so "simple".
"I could scroll through this all day long,I love it!" Haha you are are really something, these phrases makes me come back every time and watch your videos, keep up the good work!
Worked on these on a daily basis, back then. The grim reality was if you could not fix it under about 2 hours tops it wasn't viable. However I never seemed to get tired of that moment when, YES! I've fixed it. Regards...
Daaaaamm. I used to not get why Dave seemed to prefer classic analog electronics over nowadays programming, micros, FPGAs and digital stuff. Thinking(me), that:
Think of all the fun stuff you could stuff on those tiny chips.
Boy was i wrong.
Don't get me wrong I still love programing and micros in general.
But...
Daaaam son, seeing those schematics made a tear come out of my eye.Those are simply heart-warming.
Those belong on art museums for appreciation.
The Power Macintosh G4 Cube had an excellent service manual as well. No block diagrams or waveforms unfortunately, but it had complete take apart guides and even a few test points.
Overdampening gets closer to the end value (rises quicker than the designed condition) than the designed condition. That's why the first one measured at 160ns instead of 180ns as wrote in the datasheet.
Not sure if this has been commented yet:
That filter on the CCD is a type of filter for sure. Something similar to a Bayer filter so that the CCD can film in colour.
Love the quartz glass delay line chip! It's amazing how much can be done with some simple physics
wooohooo... that was FAST!
Thanks very much!
Greetings from Austria (yes, not Australia ;-) )
Link added.
Great blog, glad I just discovered you! The whole concept of delay lines has always fascinated me - just to think of how much information they, in effect, store - yet I never before understood how they worked. (Mostly attributable to laziness, admittedly.) Can't wait to check out the rest of your videos.
Haha, I suppose that's true! The great thing about electronics is that there is SO much to learn. When I get really confused, I just move on or find another way. When I come back to it a month later, I wonder why it was so confusing :P
I wonder if you could salvage a bunch of these for making the memory of a home-made retro computer? After all, they did use delay lines for memory back in the early days of computing. Granted, those were usually mercury tubes, but the 64 microsecond delay of old PAL delay lines might be long enough to hold a few dozen or hundred bits, depending on the clock speed.
that documentation is piece beauty! thanks so much for showing it to us Dave!
Wow! That is a beautifully made service manual!
Back in the 1980s, the TV station I worked for bought two Sony (sold under the RCA name) 1" helical scan VTRs. Those beasts cost around $350,000 each! The service manuals exhibited the same detail as this one. However, the English language descriptions and commentary were atrocious, in terms of grammar, spelling, and understandibility! If someone buys a piece of equipment for more than a third of a million dollars, I think one would expect the company to hire a competent translator.
Clyde Wary In 1980s dollars that's got to be comparable to well over a million today.
ElectronSpark Just a hair over a million.
i remember working on the old beta and vhs recorders had one or two of those. did take one apart looked about the same :)
That's an outstanding manual. If only they made them like that nowadays.
My initial thought with the delay line was, 2 Hours? Surely not!
a thing of beauty an a joy forever!
That service manual resembles a Tech Pub for Navy equipment. Very nice!
Well, when you think about it though, there are two things to consider:
1) Service manuals generally are intended for authorized technicians, so they don't come with the product when you buy it; and
2) in products today, "service" generally means replacing an entire board (if not the whole product), so no need for detailed service manuals.
It's sad (IMO), but it's basic economics.
I work as a broadcast tech for Channel 7, and our everyday shoulder mounted Sony cameras are probably worth more than your car, certainly mine :) Body only is anywhere from $20-30,000, and lens are between $11-15,000. Very impressive piece of gear though. Dont even bother asking what the main studio cams and pedestals are worth :)
that datasheet is so beautiful. they really don't make them like that anymore. You're lucky if you get a block diagram
I have an old Philips video player and you could hear squiring from one of it's delay lines. It was a few times bigger than this one though :)
Pretty much what it sounds like. You put a signal in one end. After some, usually very accurately specified, delay - the same signal comes out "the other end".
My many years of watching analog telly in the UK have proven to me this technology does indeed work reliably.
I think waves can intersect each other and if they're out of phase with each other, nothing happens to them. Go run a bath and wiggle your fingers in the water and watch what happens...
What I like is how this evidently arcane and dead-end technology was improved until something better (digital TV) came along. It's like opening your modern PC and finding clockwork :)
Wow. The world of analog design is amazing. That's the fun stuff. :)
There are still some widely used devices based on acoustic principles as well, such as the SAW (surface acoustic wave) filters. Very common in RF frontends.
Whenever I see these videos, I get jealous that I don't have as much experience as this guy :P
Yes, it is quite brilliant. You have an example of better engineering in video recording for the day?
The filter is know as an optical low pass filter. It helps to prevent moiré.
2 transistors, 6 diodes 1 zenner 2 big caps and a bunch of resistors. I'd love to see how they arranged them in that thing :)
I've got the full service manual for my old GR-S707 JVC camcorders. Sadly though it just takes the unsolvable problems from being electrical to mechanical calibration. I've got a vectorscope I can eyeball problems with, but without the special diagnostic and torque-loading tapes, test-cards and test sig generators.. well, you can't readily use any alternatives. The custom test gear just doesn't exist anymore.
Now that is fascinating!
Polarization is more easily done from the lens. The reason that side light doesn't work is because the actual sensor is sunken in a fair amount into the matrix. The RGB we see is simply the filters.
The speed of sound in this material is about 2800m/s. The distance covered by the ultrasonic signal is about 18cm. All a bit of a guess for distances.
My piezo delay line has 3 pins, not 4. Maybe one is common, so only 3 pins are really needed?
The resolution, mostly. Search wikipedia for "PAL". Another is SECAM. Just competing/different encodings based on region.
I love the fact DAT tapes were based on similar technology to the helical scan.
It does work that way. Multiple sound waves can travel through air without distorting each other. The solid medium works the same way.
The coax probably has a wider bandwidth. Analog video needs less than 10 Mhz, but any oscilloscope with a delay line is going to need at least 50 Mhz.
In all seriousness, how do you know so much Dave? I'm a 20 year old amateur electrical engineer and thinking about it 24/7... Do you have any good resources that will take my knowledge to the next level? Thanks for all the effort you put in your videos. - Nick
PAL is 625 scan lines at 50 fields/sec (25 frames/sec)
NTSC is 525 scan lines at 60 fields/sec (30 frames/sec)
That was very interesting. I am amazed at how that device works. I always love these videos where you explain interesting components in great detail. Now to go rummage through my pulled components to see If I have any of these.
64uS of course is a line duration on a 625 line PAL TV.
So cool!
So that's what that component is. I have one of those and couldn't figure out what it is or what it does.
I would've liked to see interactive measuring from that larger delay line component.
Attaching it to oscilloscope and try to manipulate the physical waves(block them with finger or something) and see resoults on the delay waveform.
I don't know does it work without the top cover though.
If you replaced this with digital, using an ADC, RAM to store it in, then a DAC, I wonder how much RAM you'd need? I guess that 8-bit would be enough resolution for whichever signal it is, chroma I think (since that alternates by line in PAL), I think 8 bits would be comparable to the dynamic range of ultrasound bouncing around some quartz. And this thing would need a lot of amplifying at the receiving end. Wonder how much exactly? Wouldn't crosstalk be a big problem?
Wonder what it's dynamic range is, and what frequencies it can take? Is the signal modulated onto an ultrasonic carrier, or just sent in plain, since it's gonna be high-frequency anyway.
All in it's great to see how our mysterious ancient ancestors did things in the dark analogue days. Now for 90% of problems you just stick a CPU in it and do everything in software, and then some. I'd use RAM as a buffer, and probably wouldn't need the ADC / DAC since it'd be a digital signal anyway. Wouldn't need a delay line actually, I'd just read whatever data I need as I need it.
Amazing too how many PCBs and components in there! And this was portable, and expected to work! Most of the time. Amazing that it did.
And those dozens and dozens of what look like little trimmers, either pots or capacitors. Were they all adjusted in the factory by hand, by a person with some test equipment? Or a special jig with plastic screwdriver bits, computer controlled to set them all as the computer monitored the signals?
No wonder camcorders were bloody expensive in 1985. Looks like they're right on the edge of what's possible, and quite a bit beyond the limits of what's practical. Insane! All that stuff! And now it'd all fit onto one chip. Now it'd all fit into software.
It'll be an early camcorder, too. Not much before that, you had a separate camera, with a separate VCR running on a (separate) battery pack, in a bag slung over your shoulder, or maybe your assistant's shoulder. We had an old setup like that at school, obsolete when we had it, with separate camera and recorder. Battery possibly nicad but almost certainly lead-acid and would have weighed a ton and lasted 15 minutes.
And now you can get HD recording for hours, onto an SD card the size of your fingernail, with a camera half the size of a packet of chewing gum. Cheap enough to throw away. Ah, progress!
I really enjoyed this look into this video camera, but I'm also slightly disturbed that in order to do so it had to be destroyed. Or did you put it back together and get it working?
I'm greatly inspired by this phenomenal service manual and i feel noob too :/
Love your videos, love your enthusiasm!
Dave, excellent video. This is back to basics and how things should be these days as well... at least the critical stuff :-)
Anyway, some day you should have a look at any products from Hitachi, an amazing company that produces absolutely anything you can imagine, they do the best documentation you can see around, still these days...... I don't know about consumer electronics, but talking about enterprise storage for example... anyway, keep up the great work!
I'm looking for a better explanation of the multistage LC delay line. I understand what an LC filter does, but I don't get how you can just put three of these in a row and get out a relatively undistorted, delayed signal. Is there a better explanation somewhere?
ipavemyownroad
GIYF ffs.
It is polarization. 90 degrees out of phase of the rotation. A vertical polarization so to speak.
Why didn't you hook the scope up to the second package?
compare that with some blue ray players that generate pal secam ntsc and hdmi on a board 8 inches wide.
Hey Nick, just wanted to agree with you, I've been designing circuits for around 3 years now.(Started with a Z80 processor and built a motherboard for it. I've also made some circuits inspired from the TTL Processor you can find online) I'm constantly confused by a LOT and it took a lot of effort when I first started.(Granted I was 13) So I'm looking to see what dave says too :D
Physics is just amazing.
"Asahi Glass Co."? I wonder if that's the same company that produces Asahi beer?....a very good beer, by the way. Judging by the propensity of Japanese companies to get involved in many different fields, I'd guess they are the same.
*""Asahi Glass Co."?"*
May have had something to do with Asahi Optical Co. that led to the Pentax SLR camera brand.
Haha, Asahi Glass Co., which is the biggest glass company in the world and the company name was changed to AGC right now, is completely related neither to Asahi Beer nor Asahi Optical. You know, they have the electronic division to deal with electronic products as one of the glass applications as well as their major items like building glass, automobile glass, tv glass and so forth. And they developed this key electronic device for VTR, CTV and VC by themselves in the latter period of 1970's when the market was going to expand, but they had failed to develop the precise glass material itself which density must be extremely stable all the time to define the delay time as the length (Time = Length/Velocity, and Velocity is proportional to (1/Density)^1/2). So, they had no choice to use the glass substrate from the other glass companies such as Schott Glass in West Germany and HOYA in japan. This story was the top confidential at that time. You know, i was a person in charge of the development of the glass delayline in Asahi Glass in 1982- 1994, haha!^^
When solid state DRAM was way too expensive, computers used these for storage.
This might store 1KB with good modulation, so even then you would need many of these to make a 64KB IBM PC
when working with powered boards should remove rings, watches and other metal objects from the hands - they can short-circuit board
The problem these days is that devices dont't get serviced anymore, they get thrown away, because it's cheaper to give a new instead of repairing. The only thing service technicians is to check and exchange complete modules, everything else is far to expensive. What a shame, in respect to recsources and and fully educated service technicians.
oh come on man!! where is the oscilloscope on that last one!!! great vid btw
Lol Dave you have a service manual for this thing and you will not try to fix it!?
I am realy disapointed, this videocam is older than me and it could be a great exhibit for somebody in love of old electronics
If I understand analogue camcorders correctly, then there is no concept or processing of an entire single frame. Everything exists as, at most, a single raster line, though there are signals present which indicate vertical flyback. Fascinating to learn about how the signals are pushed off the CCD, as there are clearly not the same number of connections as pixels/picture lines
Awesome stuff!!
subscribed, hope to see more about this one!
Fascinating! Thanks.
I'll see you your Sony service manual and raise you a Tektronix repair manual.