Tektronix TDS 744A teardown and repair

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What's inside a 1990s Tektronix TDS744A digital 4-channel 500 MHz oscilloscope, fixing it. One channel has a huge DC offset. The monitor has some problems - the colors are not working, it shows weird dissolving circles. It's a CRT-LCD hybrid - a monochrome CRT tube with a solid state sequential color filter (liquid crystal color shutter / LCCS / LCS / NuColor).
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9 июн 2024

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Комментарии : 125

@redpheonix1000 17 дней назад

Looking at the insane internals, this thing must have been ridiculously expensive when it was new!

@deanagoes2791 17 дней назад

Iya harganya bisa membuat kita mencucurkan air mata 😭

@allcrafter3747 17 дней назад

It's still 700€-3000€ (in Working condition) on eBay. So yeah. ChatGPT told me it was about 14.000€ originally.

@atmel9077 17 дней назад

@@deanagoes2791 Maaf, saya tidak mengerti apa yang Anda katakan karena saya tidak berbicara bahasa Indonesia. Tapi ya, perangkat ini pasti sangat mahal.

@perhansson6718 20 дней назад

Around the 4:46 timestamp we can see that the board has a Dallas DS1486 timekeeper and Benchmarq bq4015YMA NVRAM, these both have internal batteries with a guaranteed 10 year lifespan, probably they are very close to failing: you should research if the GPIB interface on the rear or floppy drive can be used to dump the calibration data before it's too late!

@suruadamable 17 дней назад

I have an older model, the TDS 460A. It was broken when it was given to me, it could not boot. Turns out it was just that the batteries were bad. Luckily in that scope they were external, not in the chips, so just removing them fixed the booting problem. Of course now it can't keep settings and time but oh well.

@aionceres7086 17 дней назад

I would expect that such a system would store the important calibration data in a static memory. Since the device is from 1994, it is unlikely that the batteries made for 10-years can survive 30. Thus i guess the calibration data is not dependant on the batteries.

@perhansson6718 17 дней назад

@@aionceres7086 The scope is not 30 years old, the datecode on the chips is year 2004 week 35 for the Benchmarq and year 2005 week 26 for the Dallas. Normally the chips last 20 years in my experience but it depends allot on how it was stored (temperature) and obviously more how much it was turned on. The Benchmarq chip stores waveform data, the scope can work without it, but the Dallas RTC stores scope options and is the real time clock, normally when they start failing the clock stops first and we can see that here: the year is 2040 on the scope yet it still has the options working on bootup. And you saw the post above mine where suruadamable says his didn't even power on when the batteries where dead, so what use is it then to "possible/maybe" have the calibration data stored in a non-volatile flash or eeprom memory if the scope is anyway not going to boot and the chips are not even socketed?

@douro20 16 дней назад

There are drop-in boards which replace both and they will be a good amount cheaper than ordering the Dallas replacements.

@askjacob 16 дней назад

@@aionceres7086 I think you mean NVRAM (although usually a small EEPROM) not static ram. Static ram is the one that needs battery backup

@My_Gaming_Mind 17 дней назад

"Is it instantly posting the waveforms on Instagram?" lmfao

@Mr.Leeroy 15 дней назад

8:37 as well

@drdrums1 17 дней назад

"Danger High Voltage" -- I'm starting to like it. 🤣🤣

@niemam5825 17 дней назад

6:19 - Hello mr. Dan :D

@fadate7292 17 дней назад

Technology Connections : LCCS: The LCD / CRT Hybrid from JVC Mindbanging.... mindbending...

@michaelturner4457 17 дней назад

I was just going to comment on that myself, as soon as I saw this CRT with LCD color shutter.

@perhansson6718 17 дней назад

Thanks, had never seen that video, a bonus point is at the end of it we can see the same error as is shown here, it happens when the display has no power so that is a good first place to look :) Also his followup "Connextras: The JVC LCCS monitor has some quirks" is worth watching too, shows more about that interesting pattern and how it works...

@douro20 17 дней назад

This was introduced long before JVC made their LCCS monitors. The Tektronix 5116 had an LCS display all the way back in 1984.

@LabArlyn 14 дней назад

Is this the display type that commonly used in airplane cockpit ?

@douro20 13 дней назад

@@LabArlyn Yes there were a few which used liquid crystal shutters, including one particular system from Eventide (yes, the same company which produced the first digital audio processor).

@Todestelzer 12 дней назад

The beauty of those old machines is that you can repair them. Most of the times you get the circuit diagrams too.

@TwelveBaud 17 дней назад

The GPIB port is for hooking up to other equipment like counters, voltage generators, high-precision voltmeters, modulators, plotters, etc, usually manufactured by Hewlett Packard. The Centronics port is for hooking up to a printer. The RS-232 port is for hooking up to a computer; although the oscilloscope itself can run the printers and GPIB equipment, the RS-232 port needs software on the computer that can understand whatever protocol Tektronix uses.

@TheRailroad99 17 дней назад

GPIB these days (and probably also when the scope was new) is mostly used for ATE (Automated Test Equipment). Like the serial port, but it's a bus so the computer must only have a single controller card. It's a rock solid connection. It also supports interrupts ("service requests") so you don't have to poll for a finished test result. The HP equipment other than ATE stuff (like plotters or calculators acting as a master) was mostly an 80s thing AFAIK

@SlaVoy 17 дней назад

Nice. Back in the days you could buy a house for it (at least in Poland).

@WagTsX 19 дней назад

such a good start, now waiting for the color shutter fix. The first scope I used in my life was a Tektronix, but I never explored this LCCS technology before.

@mrnixie 16 дней назад

Good grief! What an absolute space ship indeed! So much MECHANICAL engineering. Just compare the chip count with a modern counterpart - amazing

@Architector120 17 дней назад

As far as I know, almost all digital oscilloscopes of that era used a VGA interface to communicate with the CRT... Screen can be easily replaced with a modern TFT\IPS LCD with Scaler Board.

@SeanBZA 17 дней назад

There are CRT and colour kit replacements available that replace the entire CRT and colour panel with a TFT LCD screen, that is a brighter and longer lasting fix, and which are a drop in replacement. Done because, despite being a scope with slow as paint dry response to controls, they still are reasonably good scopes, and are specified in a lot of military service shops as the scope to use, so the fixes are to keep them running. That hybrid input board though is no longer made, nor the input section at all.

@gorak9000 17 дней назад

If they have monochrome screens, they're probably using something more like MDA (monochrome display adapter) - it's a very simple digital/ttl version of VGA having a vertical and horizontal sync, and a digital video signal, but it only supports on or off. There's also another standard that's more like CGA where there's multiple data pins, and they're used together for intensity control, so you can have more shades than on and off. Those ones are pretty easy to convert. But then there are others that actually use vector displays, and those require elaborate logic (aka probably an fpga) to convert the vector graphics to whole frames to present to an LCD. They all tend to use non-standard timings compared to usual video standards.

@askjacob 16 дней назад

@@gorak9000 considering it has a VGA output anyway, even if the internal connections are odball, you still have a way to find good VGA signals in there

@Brian_Of_Melbourne 13 дней назад

Definitely worth connecting the external VGA to a monitor. The colour information may well be present in that signal. If it is then - as other commentators have suggested - find a modern LCD VGA module to replace the whole CRT & LCCS assembly. It is worth searching YT for videos on that subject.

@erikziak1249 17 дней назад

10:26 LOL Torque sequence like on an engine head. 😀 Your humor is hilarious.

@gorak9000 17 дней назад

It's not out of the question - when the torque of the bolts is providing a mechanical connection between the hybrids and the main board through that interposer thing with the pins, having uneven torque on the screws could lead to bad connections on some of the pins. I highly doubt those pins are spring loaded pogo pins - I bet they're just slightly longer than the plastic frame they're in, and they rely on even bolt torque to make a good connection.

@erikziak1249 16 дней назад

@@gorak9000 I do not think the display will experience the same thermal change as an engine head, where the correct order of tightening the bolts is critical to avoid excess stress.

@BitterCynical 16 дней назад

@@gorak9000Yet to see an electronic device where torque matters beyond not being loose and not stripping threads. I have heard of a case where screws appeared to be loose in a printer but were actually like the screws on a carburetor turned by an exact amount to calibrate something, tightening them all the way resulted in terrible print quality. But an oscilloscope does not have mechanical moving parts like a printer.

@rl69782 17 дней назад

I have the younger brother of your 'scope, a TDS524A. Luckily, the LCD color shutter is still working as is the rest of the scope. I plan to use an LCD display panel with VGA input if/when the CRT or LCD shutter dies. User interface is slow. I agree with the other comments about dumping the calibration data if you can.

@ronniepirtlejr2606 17 дней назад

Beautiful technology from the 90s. Actually looks like alien technology lol. Can you Imagine how much they would charge today for something they put that much work and Technology into?

@SeanBZA 17 дней назад

Tek still sells the replacement units, that are much improved, but still use similar architecture, though they still use the same old ASIC's in them. They much have a good number of the wafers in storage, and enough packaged and tested chips and boards, to keep on making what is now a 30 year old design, and still selling it. Superceded by at least 3 generations, but still a listed offering, though they are pricy, but still lower when compared to the inflation adjusted cost when they first got offered.

@1pcfred 17 дней назад

They were as busy as beavers at Tektronix. Beavers in Beaverton Oregon!

@tvelektron 17 дней назад

I did never see a display like that, so interesting...

@Slay3rOne 7 дней назад

I hope you will get it fixed! Would be very interested in seeing some of those signals driving the CRT circuits! I recently got my hands on a complete CRT assembly exactly like this one, with a brand new tube, and one day I need to figure out how to generate the correct types of signals to get it working without the original Tektronix scope if possible. That would for sure be an interesting small color CRT monitor, with that very special Tektronix NuColor technology.

@NikiBretschneider 17 дней назад

This thing is incredibly slow and laggy, the firmware is just horrible. As far as I know the software is written on the top of the vxWorks, which is pretty typical for equipment of that era, and helps you a lot if you run into some "computer issues", but that's not your case. The most common problem on this device is leaking electrolytic capacitor. Almost every electrolytic capacitor first fails electrically and then, after some time, leaks. So as the device stops working properly, you just replace the failing capacitor and you are ok. But not in this case, because electrolytic capacitors in this device leak before they fail electrically and the leak is highly aggressive, so it dissolves nearby traces on the PCB, which turns simple capacitor replacement into a nightmare. The second ticking bomb are those two Dallas lithium battery backed up memory/rtc chips. That "alien technology". In fact, this fails very often, but reseating that hybrids typically solves the issue. In fact, as you open that part of the oscilloscope you should recalibrate it, but this requires ancient PC (386) with some specific ISA GPIB interface card and some special software from Tektronics. In my opinion you don't need to run into this calibration thing after reseating that hybrids. Do not mess with that rocker switch on the top board. This enables writing into a calibration memory and it also enables booting into some weird GPIB bootloader (I personaly don't mess with HPIB/GPIB/IMS until I have to, it was horrible and kind of prehistoric technology when it was new, now it is about 50 years older.) which opens the possibility of bricking whole device. That display issue. It looks like the color shutter is (at least partially) disconnected from its driver. It could be bad driver, but maybe, if you are lucky enough, it could be an easy fix. All in all, it's 500MHz DSO, which is definitely nothing cheap, even if it is old. It's useful when it comes to some TDR measurements or some basic signal integrity… Welcome to the world where "light speed is too slow" :3 .

@UpLateGeek 17 дней назад

Those are some pretty good specs, it would even give a lot of modern scopes a run for their money. Obviously the new ones are going to have much nicer displays and UIs, especially in terms of resolution and responsiveness, but I'm sure it will be more than good enough for the kind of work you're doing. Just make sure when you're moving it, you lift with your knees, not your back! 😁

@amkp40technology 14 дней назад

*04:50** SUPER COMPLEX CIRCUIT 😱😲🤔😀😀*

@KeritechElectronics 17 дней назад

A thing of beauty and a joy for ever! Good thing you got it. Hope you'll recombobulate it!

@tinkmarshino 17 дней назад

blood hell! Alien technology!

@gordonwedman3179 13 дней назад

That scope has a lot of options. All displayed on power up. I have a 784 and the color display is very nice. There is a fellow on eBay selling replacements for the NVRAM chips, around $100. He recommends replacing all those small electrolytics.

@CanizaM 16 дней назад

At first I thought that weird colour effect on the screen was a "theme" background image feature!

@mikepettengill2706 14 дней назад

Congrats! Keep going!

@Alexelectricalengineering 20 дней назад

This is awesome 😎😎👍👍👍

@foobarables 17 дней назад

Just a few remarks. 1. The displayed image size seems off. It should extend to almost the edges of the screen. 2. The 5 V bus requires a lot of current. On the SMPS board you will find close to an inductor some large capacitors in placed parallel. They caught fire when they went up in smoke leaving a hole into the SMPS board.

@kamilhorvat8290 17 дней назад

Don't turn it on, take it apart.

@mernokallat645 17 дней назад

As a nerd I like CRTs, low pressure and high pressure discharge lamps and other stuff that average (dumb) people see as obsolete, heavy inefficient junk.

@LawpickingLocksmith 17 дней назад

Not much inside considering they hat to make it longer than that short CRT dictates us. Just joking. They were making scopes with vacuum tubes and a round CRT. This one still has mind blowing specs. Once all the backup batteries are replaced and all supplies brought up to spec this would still be worth a fortune. Can't wait for the repair part.

@otherbasis8505 17 дней назад

While repair of such a display is very interesting and I'm excited to watch that attempt, in practice people simply replace the whole display assembly with an appropriately sized, VGA enabled, LCD panel from Ali Express. It is cheap and cheerful. Admittedly, such a replacement is not much of a value from "content" point of view...

@Betterstartnow 19 дней назад

Sweet scope

@tajtrlik1111 17 дней назад

Gratulujem k získaniu tohto osciloskopu, jedná sa naozaj o zložitý prístroj, ale keď si ho opravíš môže ti ešte dlho verne slúžiť, samozrejme sa budem tešiť na ďalšie videá z opravy.

@bulwinkle 16 дней назад

Comment for the algorithm.

@AJ-Secular 16 дней назад

That's right! Dany deserves much more than that.

@andymouse 17 дней назад

Awesome !.....cheers.

@johnwelbourn3811 17 дней назад

Amazing complexity, there must be an easier way to produce a functioning oscilloscope, even with 4 channels. Your cat is hilarious BTW.

@309electronics5 16 дней назад

Newer scopes have most logic embedded into a Cpld or fpga or special asic. New scopes are basically that special asic + channel logic + application processor that often runs something like a custom linux/android/winCE

@thetechgenie7374 17 дней назад

Replace those SMD capacitors, thet leak and eat traces on the board. Your still works, so changing them is insurance. Also read the old NVRAM and program new NVRAM

@My_Gaming_Mind 17 дней назад

the scope has a date code on the back. It says June of 1998

@NominePater 16 дней назад

Hi, Dany! I hope #YOU would read me... In a few minutes, I would post a hyperlink that may serve you (just in case you've planned to translate your Engineer Electric Kalculator into Spanish...) and Thanks for ALL those years producing ELECTRONIC contend!

@VIPINSAINI_20 17 дней назад

FINALY SEEN YOUR FACE TODAY, OR AT LEAST REFLEXTION OF IT

@whitenigga776 12 дней назад

Yes 😂

@conkerconk3 17 дней назад

2:24 Freaky!

@TheDefpom 17 дней назад

Looks more like AC riding on the DC control circuit to me, only just started watching, but my bet is cap problems.

@SeanBZA 17 дней назад

No, those boards and ASIC's are famous for thermal issues, and drift when hot, along with contact issues as they age. Plastic and board creeps under the screws, so making loose contact, and the thermal paste dries out.

@lmwlmw4468 14 дней назад

Nice.

@MrGuano11 17 дней назад

When do we get the schematics?

@PrajjalakChattopadhyay 16 дней назад

Ah, the centronics bus, GPIB bus and RS232 interface!

@MyTubeSVp 17 дней назад

What is this color shutter thing you are talking about? Maybe you can enlighten me in the next video?

@EliasJosRamirez323 17 дней назад

0:21 why's the extension cord has burned? I have some questions about it

@1pcfred 17 дней назад

Moar salt!

@sanitaires 17 дней назад

Хороший подарок. Для Tek DPO точно выпускаются фанатами наборы, для мода на LCD дисплей, с нативным цифровым подключением.

@larrybud 17 дней назад

6:00 don't touch the high voltage power supply kids, especially after running it and not discharging anything. Geesh

@TechGorilla1987 17 дней назад

Tell that to Shango066.

@liam3284 17 дней назад

Heard the story about repair techs being thrown into the back wall, due to a picture tube discharging into them.

@larrybud 17 дней назад

@@liam3284 Thousands of volts, this dude is setting there touching everything with a bare finger.... Only a matter of time.

@rayofcreation3996 6 дней назад

You can connect an external monitor to make it even more cumbersome! 😂

@tpa6120a2dwp 17 дней назад

I had one of these on loan a few years ago - the user interface was as sluggish as yours, I'd say its not broken (or mine had the exact same problem...). I own an old Nicolet Pro 42 which is also from the same era and just as sluggish to respond. Very annoying to use compared to todays oscilloscopes. And the cherry on top is that the only way to turn it on is the big mains switch at the back, it has no power button on the front.

@techtinkerin 14 дней назад

That must have been expensive when it was new

@TechGorilla1987 17 дней назад

@0:27 - I did not know that Techtronix made a jet version of their oscilloscope.

@TheDefpom 17 дней назад

LOL @5:12

@rayofcreation3996 6 дней назад

Is it instantly posting the wave forms on Instagram? 😂

@thevoidedwarranty 17 дней назад

Also dumb the calipration data & fix the battery .

@NikiBretschneider 17 дней назад

It's much worse. This unit does not have battery that could be simply replaced, there are two Dallas chips with lithium battery inside soldered to the board.

@1pcfred 17 дней назад

@@NikiBretschneider you can dig those batteries out of Dallas clocks. People do it.

@thevoidedwarranty 17 дней назад

@@NikiBretschneider yea that's what i meant .it's tedious but very doable

@sergepetrov8598 15 дней назад

Why tin whiskers in pre-RoHS device?

@Brian_Of_Melbourne 13 дней назад

What do you think solder is made of? Hint Tin & Lead.

@sergepetrov8598 13 дней назад

@@Brian_Of_Melbourne Sure, and you need pure tin for whiskers. Where they care for reliability, they put 3% led, and get no whiskers.

@Brian_Of_Melbourne 10 дней назад

@@sergepetrov8598 I've just done some reading, and clearly I stand corrected.

@555-xd1fo 17 дней назад

This is an old oscilloscope but it contain a lot of settings like modern oscilloscopes But why there is a floppy drive inside 🤔

@Agent24Electronics 17 дней назад

To save waveform images, USB flash drives didn't exist in 1994

@liam3284 17 дней назад

Just like the Yokogawa scope where I used to work. The floppy saves a screen image or sample data. We were trying to find a "virtual" floppy drive to replace it because floppys were hard to buy.

@555-xd1fo 17 дней назад

@@liam3284 thanks

@NikiBretschneider 17 дней назад

@@liam3284 In fact, it's easy to buy a floppy disk here (made by MediaRange), but they are not cheap (10 pcs for $35..two years ago they were for under $20). I bought my oscilloscope with a floppy drive emulator installed (Richpeace RP-SFDR) and I tried 20+ USB thumb drives to find TWO, that worked with that emulator, they are both 20 years old. And, on the top of that all, it limits the amount of data on the USB drive to 1.44MB, because it emulates the whole thumb drive as a one floppy. I am still looking for the original floppy drive to replace this kind of sh., because it's much easier (at least here) to buy a new floppy disk than a new USB thumbdrive that works with that emulator. There is also something called Gotek, but I never tried that.

@Agent24Electronics 14 дней назад

@@liam3284 You might have luck with the Gotek floppy emulator?

@pey-yote 17 дней назад

What component would emit x-rays?

@chrisg6597 17 дней назад

The CRT.

@SeanBZA 17 дней назад

@@chrisg6597 Yes the CRT, as it runs at 12kV anode potential, and the filament is biased to around -300V along with the cathode, to make driving easier. Yes leaded glass used for the CRT in the front panel, but the tube walls are not leaded because of the conductivity it allows in the glass, so there is still a small but noticeable amount of soft X Rays emitted from the bare CRT, thus the shielding to attenuate it to low levels, and the warning stickers, so you do not operate it without the shield in place for long periods. However you would have to be within 5cm from it for months, continuously, before the dosage became equal to a single dental X ray.

@liam3284 17 дней назад

Don't stand next to the TV! Hm, though a computer monitor was worse. What good fortune people have today.

@johnsmith7676 15 дней назад

@@liam3284 Good fortune? Au contraire... Quite the opposite is true, I assure you. You shall see this is true soon enough.

@SigiCZ 14 дней назад

nenatahuuuj to taaak prosiiim těěě

@mernokallat645 17 дней назад

LCD display = liquid crystal display display LOL. I also heard people saying AC current, LED diode and so on.

@beleteshebabaw6785 17 дней назад

I joined this channel probably before you had 5k subscriber, pls can you reveal your face.🙂

@SeanBZA 17 дней назад

The other channels have had his face on, Czech them out. But that voice is very good, lovely accent there, and really good English for a person who speaks a totally different language, and a different alphabet as well.

@JDTeam 17 дней назад

if you are that curius, look at 6:18

@beleteshebabaw6785 17 дней назад

Ohhh, thanks.

@NikiBretschneider 17 дней назад

@@SeanBZA That "different alphabet" made me laugh a lot. It may look like completely different alphabet, because of that „mrda háčků a čárek nad kdejakým písmenkem“, but it's heavily "augmented" latin. Cyrilic looks different, чески се тим в ноузи псат да, але йe то як кдиж сере а малуйe…

@electronicengineer 17 дней назад

@@SeanBZA I agree with your words Sean. I absolutely love Dany's voice and his English can rival the English spoken by many Americans which I routinely listen to! Also, I see what you did with the "Czech them out." sentence... Very clever, you are Sean. Best to you, Fred

@1pcfred 17 дней назад

They never made anything quite like Tektronix in the Soviet Union. So alien technology indeed.