EEVblog

[@EEVblog]

It looks like this TDS540D can be upgraded to the colour TDS754D! www.eevblog.com/forum/repair/conversion-tektronix-tds500-to-tds700-color-oscilloscope/

[@Daveyk021]

EEVblog please fix the crt properly

[@ChipGuy]

I have seen CRT to TFT conversion kits for these on Ebay. They also advertised "convert your mono scope to a color scope". Maybe you can try one of those. And of course there is a thread from2012 on your forum: www.eevblog.com/forum/testgear/color-tft-screen-in-a-tektronix-tds500-600-or-700/

[@izimsi]

Just what I thought when I've seen it's actually capable of displaying color.

[@nobby91010]

cor blimey you"l av 2 do it that way then lol

[@gblargg]

Of course a color CRT has inferior resolution due to the color triads.

[@johncristianjcivan5429]

Fix it ! If not possible go to plan B and replace CRT w/ LCD. By any means, make it work again. it's a wonderfull piece of engineering art.

[@mycosys]

Honestly the CRT isnt worth fixing unless you are a CRT nut, UHT, xrays - its not something most people want to do anymore, and the improvement of an LCD in terms of power and simplicity and reliability are real

[@mycosys]

@@Psyden5757 A scope that deep is pretty much always going to be a CRO - the depth is there mainly to allow for the length of a CRT

[@autogolazzojr7950]

@@mycosys A digital crt oscilloscope with have a shorter crt with magnetic deflection.

[@mycosys]

@@autogolazzojr7950 which doesnt change the fact that if its that long its almost certainly a CRT. Im sure someone also tried a side tube

[@FooBar89]

there are superior modern alternatives, not sure it’s worth fixing by any means

[@bogrick1947]

Wish I had dumpsters around here with things like that in it *sighs* Edit: You've gota go for the retrofit of a color LCD panel for that..... Just look at that surface mount porn on the main board !!!

[@DrakkarCalethiel]

Richard Wayman I wish I could get anything. 10 years ago you could get everything. From microwaves to old PCs. Best score was the P3 machine. Works awesome as a DOS retro gaming machine.

[@mbirth]

Just beware that there are cheap ass LCD kits that use the VGA port on the back and there are the more "pro" models that convert the internal signal used for the CRT so you can still use the external port. E.g. simmconnlabscom.ipage.com/store/page5.html Also on my TDS784D, colour is made by using a colour lcd in front of the CRT. It works similar to the colour wheel in DLP projectors or the Vectrex 3D Imager.

[@cthulpiss]

@@mbirth " colour lcd in front of the CRT " ? wow! how does it compare to regular lcd?

[@VK2GPU]

Same! Best I've found dumpster diving is some still good vegetables. Not any mostly functional scopes :(

[@mbirth]

@@cthulpiss A bit blurry, because the graphics come from the CRT and the LCD only adds the colour. But better contrast. Someone made a comparison video: kzbin.info/www/bejne/gpKuaoB_jtJpgJo .

[@NikiBretschneider]

First of all, this problem is hidden somewhere near the horizontal (HV) transformer, which is also used as a power supply for anode voltage, fillament and horizontal deflection coil. Measuring anode voltage is difficult, but it's easy to check the fillament voltage (use TrueRMS voltmeter). If it is lower than expected (use screen's datasheet as reference), then you are sure, that the HV transformer works improperly (for some reason). The second thing you should do, is disconnect the horizontal deflection coil (load the deflection coil output with approx 30-40Ω non-inductive power resistor, which is enough to not to destroy the HV transformer by inducted voltage on non-loaded output) and measure the fillament voltage again. If it is correct, then your problem is some shortage inside horizontal deflection coil. If it is still low, then the deflection coil is probably OK. Next check the horizontal amplifier. First of all. Disconnect the PSU from the horizontal amplifier and check the PSU voltage. If it is low, then your problem is not inside the monitor part, but it's somewhere inside power supply unit. If it is OK, then reconnect the PSU to the horizontal amplifier and measure the PSU voltage again. If the voltage is low, then the PSU is overloaded. If not, then your horizontal amplifier have lower gain than expected. If the PSU is overloaded, then check the compensation capacitor connected in parallel to the primary winding of the HV transformer. Desolder the capacitor and measure it. If it is OK, do not solder it back and remove also the HV transformer and check, if your PSU is still overloaded. Yes means that the horizontal amplifier failed. No means, that you should check, if you have some DC on the horizontal amplifier output. If there is DC, it means, that horizontal amplifier failed. If not, then it is near sure, that the HV transformer failed (winding shortage in most cases). If the PSU is not overloaded and is working properly, then the problem still could be caused by the compensating capacitor, HV transformer or horizontal amplifier. So. Check the compensating capacitor (which is easy to do), then replace the horizontal amplifier (which is cheaper than a HV transformer) and then the HV transformer. Short version: Check if the horizontal deflection coils are OK (as described before). Then check the PSU voltage. If it is low, then desolder horizontal amplifier. If it is still low, then repair the PSU. If not, then check the compensating capacitor. If it is OK, then replace the horizontal amplifier. If it is still not working, then replace the HV transformer. Easy :3 :3 In my opinion, this is caused by PSU or by the compensating capacitor.

[@DanafoxyVixen]

Id definitely do a Memory dump of those Dallas battery-backed RAM chips before those built in batterys die and you loose potentially important stuff like config/calibration data and your left with a brick... those things are notorious

[@sbalogh53]

I also wonder what the floppy is used for. Just storage of waveform data? Or can you download optional measurement systems? I have a HP Data Analyzer with a floppy disk drive and you could load in all sorts of measurement techniques for the device. It also booted up using a floppy containing the basic OS and "apps". Probably no longer works since the device is about 35 years old.

[@jmachMega]

The complexity in these scopes is unbelievable! Nice video.

[@ferz1984]

Fix the monitor !!! Keep it original...

[@grahamgallagher48]

A systematic CRT debug/repair video would be cool. Techniques for probing high voltage circuitry and really anything that helps youngsters to play with high voltage should be encouraged.

[@someoneoutthere7512]

cap on the horizontal section is the culprit. you have low HV and it can be also seen by the narrow horizontal deflection

[@mitsuman007]

Fix it fix it fix it fix it.

[@stuartmcconnachie]

@16:50 can always put the bigger part in, but then to the right there is the same part with no space for the larger variant? Maybe the larger part does double duty?

[@redpillcommando]

I'm so envious of your dumpster finds. Good show. Also, repair or if not possible, refit with LCD.

[@video99couk]

3:14 Yes I remember the shuttered colour screens, they made me feel quite unwell.

[@shana_dmr]

Yeah, I never really understood using them in Tek high end scopes, they were big and weighted a ton anyway so why not go with normal color CRT?

[@DrakkarCalethiel]

Repair incomming? If it isn't fixable retrofit a LCD.

[@seancsnm]

Oh no! That's the scope I sold on ebay last month! Guess the buyer wasn't happy with it. The TDS640A was my first scope. I 'upgraded' to a 740(?) which is a color version since and that's the scope I use now. For a budget scope, it's very nice.

[@LittleRainGames]

Small world lol

[@JasonWW2000]

I'm sure he was joking.

[@basshead.]

Not a bad four banger scope.

[@mr_gerber]

Four banger?

[@basshead.]

+DGerber It has 4 channels.

[@TheZombieSaints]

look at that little, old-school flyback! awesome vid once again dave

[@MrBurritoMan]

Hey I have one of those! The only bad caps that I could find were in the CRT module. After fixing those everything works great!

[@EEVblog]

Which caps?

[@MrBurritoMan]

@@EEVblog I don't remember exactly which ones, just remember that it was almost all the electrolytic needed to be replaced. It looked like mine were from the same batch.

[@SupremeRuleroftheWorld]

@@EEVblog the faulty ones i guess.

[@Tedybear315]

24:10 paused the screen. I didn't see any bulging or looking suspect. Can you be more specific?

[@MrBurritoMan]

@@Tedybear315 Bad electrolytic capacitors can fail and have zero outward signs that they are bad. You need to pick up (or build) an ESR meter. With that you can measure the effective series resistance of the capacitor to tell if it has failed open, or failed shut. Every electrolytic capacitor will have an ESR, measured in the tens to hundreds of ohms. A good ESR meter, behind a solid multi-meter, is one of the best pieces of test equipment you can buy.

[@alpcns]

That's not a dumpster, it's bloody heaven. Unbelievable what you fish out on a regular basis. Fix the thing :-)

[@robertdrinkall8947]

Your the Man to fix it Dave, it would make a great video!

[@the8bitbarn836]

Go-to the utilities menu and turn up the intensity on the display. Try it...

[@BlackEpyon]

It's not unusual for those Dallas clock/NVRAM chips to last upwards of 20 years before they start loosing time. I had one on my Tandy 1000HX that only finally died a few years ago. There's a hack you can do where you dremel out the potted connections to the old batteries and solder in connections to a button cell holder and get them keeping time again.

[@Daytona574]

Commonly needed on IBM PS/2s as well. www.mcamafia.de/mcapage0/dsrework.htm

[@Daytona574]

A BR1225 holder, while uncommon, aligns perfectly with those pins. Done a few myself.

[@BloodAsp]

When I go into CNC cabinets from yesteryear, sometimes I see LCD retrofits, they look amazing.

[@PilotPlater]

what a crazy board inside!

[@kennener8446]

Run SPC (Signal Path Compensation) - that's where the wheels usually fall off. Also - you can double the b/w and sample rate on these. Simple matter of removing shunt caps and changing the 0-ohm jumpers. It's a 2M unit, which is nice - extended sample memory. The 21V regulator on the CRT board is probably gone - easy fix. Pretty much the entire CRT board runs off the output of the 21V regulator on the board, and it is a common failure point. Flybacks also tend to die, but parts/assemblies are available on eBay. I have a bunch of these beauties - fix up the CRT driver board for starters, then extend the bandwidth & sample rate.

[@johnyang799]

Again, from the magic dumpster!

[@dhpbear2]

28:40 - I vote for a CRT fix - You've never done one of those!

[@over2seeyer]

Your dumpster is worth more then my house.

[@gblargg]

One man's trash is another man's mansion.

[@packratswhatif.3990]

With the luck that Dave has in these trash bins, I am going to get him to buy me some Lotto tickets.

[@joopterwijn]

The lcd replacement is a nice project!

[@userPrehistoricman]

I feel like every EEVBlog upload these days is #1184

[@kippie80]

Fix the original crt! I have a 360 from the same era and really do appreciate the sharp quickness of crt over an lcd.

[@Factory400]

My first 500mhz scope was an eBay TDS754D and really liked it. A bit massive by modern standards, but it got me through a ton of design work.

[@gerryjamesedwards1227]

Always go for a bit of encapsulated postscript (EPS), muh-dude. It'll do all the half-tone screening for when you send your Quark file to the litho printers for your >printed< app note. I believe you can get colour screen kits for the old TDS 'scopes, btw.

[@TurpInTexas]

I have the TDS 520B and it sometimes gets cranky. The repair consists of popping it apart, and reseating the plugs, which seems to fix it for a few more years. The CRT is monochrome, and most of the video on the VGA out is too, except for when I toggle the InstaVu function, it turns color on VGA output. If I could convert it to color I might be tempted to try that conversion you mentioned!

[@marcop8273]

It shows some images, so flyback transformer seems to be fine. Alignment seems wrong, i don't think issues with internal crt video DAC, but i would try to check H-V coils driver, driver voltages and capacitors, expecially those near heatsinks on crt section. On 4:30 it seems to be same screen of 7:03 with much less luminance (check anode voltage) and horizontal deflection issues (check horizontal driver and relative voltages).

[@ve3krp]

I think I will move to Australia to become a dumpster diver...I would like to see a coloujr LCD on that scope... Nice !

[@twjonckheere]

Fix the display, remove the hard drive, replace the batteries, and replace the floppy with an IDE to SD card device.

[@edcooper2396]

That RTC has done well!

[@robinbrowne5419]

Hi Dave, I'm a Java programmer since about 2000 so this is really cool. It's good to see the original Java logo right on the scope. You ask when they stopped using Java on scopes. Gosh, I didn't even know they started using it. Cheers from Canada :-)

[@diagtula]

This is a soldering defect of a horizontal (flyback) transformer. Turn on the device and bring the neon lamp with the (flyback) transformer

[@GLITCH_-.-]

What exactly does " bring the neon lamp with the (flyback) transformer" mean?

[@Tedybear315]

@@GLITCH_-.- I think if you bring a neon probe close to the flyback and it's working? The neon lamp will glow. If the neon lamp fails to even give a hint at lighting up, possible a cold solder joint at the flyback transformer. Just a guess, but I've seen a large number of flyback transformers with cold solder joints/cracked joints create many problems on the equipment where I work.

[@SoundzRite]

Back in the day, I had aTDS520A that went dark like this. It had no CRT anode voltage. I found a replacement flyback somewhere that fixed the problem. Got a few more years out of it before the surface mount electrolytics went south. A common problem on these. I didn't see any on this D model top board. Check the other side of the analog board. If Tek had fixed the problem, it may be worth salvaging.

[@EEVblog]

Can't be the flyback, as there is something on screen, just collapsed or some such.

[@TehMG]

@@EEVblog The flyback transformer and horizontal deflection circuitry actually have a lot in common! Quite often the same transistor or IC drives both. So a problem with either part of this circuit can affect the flyback and/or horizontal deflection.

[@Mythricia1988]

I spent a while hunting for 5xx and 7xx series scopes like this on eBay a while back. There are a lot of them for sale with modifications such as color CRT's (As far as I understand, it's a simple mod to enable full color support on *any* of the scope versions), or with pre-installed color LCD replacements. So it must be quite simple to do, given that it's a popular mod. Also I've seen a number of them being sold with higher bandwidth - it seems that they all have basically the same hardware, and that a simple mod can unlock 1GHs on the 500Mhz version etc. The reliability was terrible for the A/B/C versions, they had leaking capacitors that would permanently ruin the PCB's, very hard to repair in most cases. Apparently the D versions fixed this, and is pretty much safe in that regard. This is just from what I heard while researching them though, I don't have any personal experience with them. Nice scopes for the price if you want bandwidth, and can live with the lack of modern features. I ended up getting an Agilent / HP 54642D myself instead, but I was close to getting one of the 7xxD series Tek scopes!

[@ThatOneTruckGuy]

7:10 did anyone notice it still had the time and date set?

[@chriswouse7713]

I sold an model model of this on eBay last year. It have a triangle wave input on all channels and was going though the service manual procedure, all going fine, had to stop for an emergency, came back next day to carry on and it was dead as a dodo! Very similar in construction inside!

[@Darieee]

For sure fix the stock crt

[@FireballXL55]

From the picture when you had a display on the CRT it looked like H scan problem, the left hand side was cramped into the middle. It should be relatively easy to run the CRT module outside the chassis.

[@Herby-1620]

Others have suggested the flyback transformer, which might be the case. I'd also look at the horizontal output transistor. They usually are the ones that have the magic smoke escaping first. Lacking that the solid state option looks like the best option. You need to make sure that the aspect ratio is OK as well. Good luck.

[@redsquirrelftw]

Would definitely make a cool repair video. Though it might be tricky given you can't really have it turned on and have access to LCD at same time to troubleshoot and probe etc. I like the idea of retrofitting a small LCD if you can have one that will take a x/y input like a CRT.

[@stevencarlson5422]

Shout out for the Zip drive storage :)

[@strangersound]

The Schaffner interests me more than the scope. They made such oddball specialized gear, it's a lot of fun to see what's lurking inside. :)

[@scottgfx]

Seeing the neck of the CRT, I thought it looked cloudy, like the tube has lost vacuum. You see some deflection on the tube. It looks really weak, but who knows.

[@RetroComputerStu]

I'd like to see you troubleshoot and determine the exact cause of fault with the CRT assembly. Mainly to see what I can learn from the process.

[@RichardDePas]

Retrofit with the colour LCD. Will be a nice upgrade to it. Wish I had dumpsters with this kind of stuff!

[@Torgo63]

I used the same scope in my last job for ~12 years, it was the 1 GHz version, color display. It never gave me any trouble, and the Anti-Glare screen was great (I can see the Purple tint in the video, so it looks like the B/W version gets it too).

[@antanasv2642]

You have the best dumpsters down under..

[@JimBob_Joe77]

Boy, you must have some really great dumpsters where you live? I have never known anyone to get so lucky looking in dumpsters and finding lab equipment.

[@stevefriedl3983]

I think a CRT is pretty much a vacuum tube: get Mr. Carlson to weigh in :-)

[@Stoney3K]

Carlson may have one or two of these units as spare frames, so if you give him a poke, he may be able to provide you with a spare working CRT...

[@jonka1]

Very unlikely it's the crt that's faulty. Wishfull thinking to just plug in a repair. The power supply for the tube is very high voltage and the components are highly stressed.

[@Stoney3K]

@@jonka1 I'd just replace the entire monitor assembly including the driver board as a complete unit and be done with it, that would give you the chance to drop in a color tube as well.

[@eryksoowiej4427]

You should (at least try to) fix it, and if it is impossible to do so, consider retrofitting a LCD (or any other type of) display in it's place. Also, is it possible to just get a solid-core wire with the right diameter to just push into that connector on the newly found Schaffner module? I know it isn't the safest option or the easiest one (you can propably attach aligator-clips to the wires attached to the socket on the inside of the unit, and run it without it's top/bottom cover on), but is it possible? small note: I think that the video number is wrong (shouldn't it be 1185?)

[@marshmallowkiller]

There are quite a few LCD retrofitted TDS oscilloscopes at my work and they end up being far clearer than their CRT counterparts.

[@pmgodfrey]

I swear you throw this crap in the dumpster only to "find it" and depress all of us. Cheers from the US!

[@hikaru-live]

Three upgrades: 1. LCD. 2. A Noctua 24V industrial-grade fan (can be quieter.) 3. Flash-based hard drive replacement (SD2SCSI or CF card, for example.)

[@chrisjones-fp5vd]

I'd be down for either one of those videos

[@TheBdd4]

You scored! I bought a salesman's 2 channel TDS380 demo in 1998 for $4300! because I needed a scope with storage for a unique design I was troubleshooting. My scope is like new but worth just a few dollars on the market. Your TDS540 must have cost many more dollars than the 380. I wish the 380 had upgradable memory. I bought a TDS3054 with 4 color channels but it also has very low storage memory.

[@xx3868]

If you have a CRT restorer, you can quickly check for emission to see if its really stuffed or ok and clean the guns (s). I have an old B&K 467 and love it and fixed so many arcade units and my own oscilloscopes crts ect. Then if thats ok at least you know its not the crt. I agree to try and fix the crt as it could just be something simple like that ribbon connector. Everything looks strangely clean and caps all look perfect. Its a gift that it has a lcd output as you can get a nice screen and put it in and bodge up the holder surround to look nice; but thats just details. You might find it all goes together easily and will be fresh and modern. At least you have the backup option except for the slow lcd result compared to a fast bright crt. You scored big time and as you Americans say "awesome" , but i dont know what we say in Australia!!...

[@benbaselet2026]

Gotta like that screw and pull out method

[@TheDefpom]

Very nice.. I'm a bit jealous.

[@ko2fjb]

I'd like to see you diagnose the issue and possibly install an LCD display

[@arthurvin2937]

Dave, you have to do something with your lab lighting. It looks depressingly dim. EDIT: oh ok, you actually mentioned this around 3:30. But it's not only in this video.

[@dhpbear2]

20:02 - A Dremel tool will work :)

[@richardbrobeck2384]

I could be some Electrolytic caps Dave I would try fixing it first it might be a easy repair if it's to costly you can always use the LCD

[@herbertsusmann986]

Quite a dumpster find! That would upgrade my bench scope for sure even if I had to run an ext monitor. Fix it if you can or replace the crt with an lcd.

[@akkudakkupl]

You have it too good Dave...

[@nathanmelanson]

Just noticed in the background, what type of connector is connected to the BK Precision load, at 19:08? I have not seen that before.

[@EEVblog]

Custom banana jack terminal board

[@paul.alarner6410]

did you make a repair vid of this as would be good to see?

[@fullwaverecked]

Magic dumpster, Dave, Magic dumpster.

[@Polikator]

Хороший аппарат :) Нравится.

[@waxore1142]

16:50 what do dead people have to do with it?

[@darrenthompson3696]

Hi Dave, I ahead several of these scopes and the screen are notoriously fail.

[@thingyee1118]

Angle grinder, Dremel and a file will take care of the moulded crt tube housing.

[@john62rich21]

Do you ever sell those extra scopes when you find them?

[@akhurash]

I think a LCD replacement would be interesting.

[@kajyakuzonik9130]

Please try to fix it! And if it turns out to be "impossible" then try fitting an LCD inside, please. Either way, I always learn something from your videos!

[@xtrariceplease]

Hmm.. electron gun is working, flyback still works. Could it be what's driving the deflection coils is the problem?

[@Stoney3K]

I could see no beam spot so the flyback may be busted. If the flyback was working but the deflection was dead, you'd have a very bright distorted image concentrated somewhere on the screen.

[@peregrine1970]

Convert to color AND upgrade it to lcd. Bonus style points if you manage to add a touchscreen and map the buttons over.

[@iritantNL]

How do you find all that equipment in the dumpster?I dont believe it anymore..

[@elektrokinesis4150]

verify b+ on the CRT and check the capacitors on the CRT board

[@loz11968]

If you can get the colour to work go for the upgrade but would also be interesting to see what’s wrong with the crt...

[@MattOGormanSmith]

You don't need ramdacs for a mono display. This suggests to me that you could get colour on the VGA if you can convince the firmware it's a colour model.

[@andydelle4509]

I have that scope new since 1999. But I still reach for my 50mhz Leader first when looking at analog stuff, video and audio. But the 540 is great with digital logic. is there an LCD upgrade? It does have a VGA output but I think it's still B&W, haven;t used that in years. Note that "Mr. Carlsons Lab" channel also has a TDS dumpster rebuild project video.

[@no5x937]

What are the GPS coordinates for this equipment dumpster? Good score.

[@kristoff3823]

It is good idea to fix it, it will remind me old good days of fixing CRT TV's. I am about of buying one of this scopes.

[@network_king]

A dim CRT from what I remember with PC monitors tis was usually related to the flyback/driver circuit. Something that old though too I would almost wonder if maybe wear tear/ age did not cause damage to the CRT tube and maybe the vacuum escaped. Original in a way is nice, but i would say just update it to an LCD.

[@electron_]

Hi Dave, It's one more great video as usual! Thanks! I have a problem with my TEK TDS974D, a little bit different from yours, it is corona from HV transformer. I have tried to glue put some rubber protection but it is not going. Probably internal SC or something similar. I know that this video is made 2 years ago, but I am kindly asking If you have any TDS7xx series oscilloscope to measure the voltages on the HV Flyback transformer, because service manual I can't find for colour display model so I assume the HV FBT is completely different from BW model. Any schematics will be great for my model. Many thanks!

[@Vik_ru]

Агрегат конечно уникальный..

[@scotshabalam2432]

I love you guy who came up with "RAMified TIMEKEEPER" as a chip name. You can name my babies.

[@AntonBabiy]

Surely the crt driver board is fixable! Looks like something in the horizontal driver section is failing causing low hv and low horizontal deflection

[@slick8086]

Man, the dumpsters where you live have such great stuff. The dumpster around the corner from me is full of garbage. Although I do find quite a few TV's in the alleys around here.

[@martijn3151]

Dave, Whats the address of your dumpster?

[@johncundiss9098]

QUERY/QUESTION.... Am I correct in saying that you cannot access those pots like focus and such in that CRT section unless it is together? That seems very odd. How alignment and focus?

[@paul.alarner6410]

did you ever repair this ,or did it die the same death as your psu project series and get left?

[@robot797]

fix it please

[@the8bitbarn836]

On the front panel there is a button (Display) press it then on bottom on the front panel 1 button over from the left side of the scope it says Intensity on the screen press that and turn the selector knob to the right and see if the screen comes up... (Cheers)