This Oscilloscope Is Garbage (Literally)

[@EEVblog]

Nice dumpster score! 100MS/s is still quite useful single shot bandwidth.

[@EEVblog]

BTW, KZbin recommended me your channel, it's been doing this a lot lately recommending small channels like yours, I love it. Keep it up.

[@sealiosprojects]

Thank you!!!

[@humgar]

I'd rather pay $200~$300 to get a HP/Agilent/Keysight 54645A/D than this Tek though. 54600 series is a lot more robust to aging issues, low maintanence, responsive to controls, user friendly and space conserving than TDS300~400 series. I have little love for Tek since I started fixing more and more of them. They are designed to be barely good enough to endure the service life Tek honored. HP/Agilent/Keysight had a lot more attention to details.

[@franciscoferreira-eh1yu]

Man look who is here. Maybe electroboom will join the the comment section as well😊

[@mrnmrn1]

​@@humgarThe good old Tek TDS220 is great and small. Yes the LCDs start to fail after 30 years, but lately new replacements are available from China. And regardless of what one would buy, this was FREE.

[@richfiles]

I got a TDS420A from an auction for 50 cents... Actually a _whole pallet_ of oscilloscopes... For 50 cents. It booted fine, but had 2 dead channels. I bought a dead one that didn't boot, and used a nice desoldering iron to transfer the ceramic modules from the donor scope to the one I had, and then used the calibration tools at work to calibrate it an generate a calibration certificate. I ended up selling it for half a grand, and the donor scope for parts... In the end, I only spent $60 restoring it... Well... $60.50

[@mikegLXIVMM]

12:51 The black thing is a fly-back transformer to produce the needed 15 - 20 KV to run the CRT.

[@ivolol]

Your cheap function generator may be suffering from having counterfeit / faulty opamps in its output circuit. If you are able to do basic SMD resoldering you might be able to replace those opamps with sourced known good ones like NE5532/NE5534 (I can't remember whether it's dual or single opamp it needs) and it might function MUCH better. The best thing about getting a decent oscilloscope for free, instead of $300, is that instead you could invest the $300 into quite a good lab power supply, or a good signal generator (maybe a bit of both, ~$150 a piece). Then you really have a lab going, and for half the price you'd normally pay. I'd still watch out for many electrolytic capacitors aging out when they're getting to 30-40 years of age.

[@sealiosprojects]

Agreed! I have no clue why the signal generator didn't work that time because 5 minutes before I started filming everything was working

[@mikegLXIVMM]

8:31 Cathode Ray Tube(CRT) One of the last application of the vacuum tube. It stores charges of 15 to 20 KV. Be careful not to touch the connection of the anode (Red wire that goes into the tube.) This is where it can discharge and cause a possible shock.

[@electrifyingvids3545]

12:54 I belive that is the flyback transformer. That doesn't creates x-rays. The only thing that creates them is the CRT. The transformer has shielding because it supplies high voltage and needs it to protect the other circuits from arcing over.

[@sealiosprojects]

Ah, good to know! I’m really happy I didn’t mess with it

[@splitprissm9339]

@@sealiosprojects Don't worry about X-Rays too much with a monochrome raster (computer/TV) type monitor like this device uses, or with MOST true analog oscilloscopes (not this) either. They tend to be in the 12 kilovolts or less range. Where things could get into "be careful" territory is with very specialized analog oscilloscopes (24 kilovolts and up), color raster monitors (24-32 kilovolts) when operated without the expected shielding or safety circuitry in place, very old school color TVs (which use tube based circuitry to drive the CRT) or any kind of projection CRTs (40 kilovolts and up, it seems above 32 kilovolts is where the X-ray issues start to get serious...). BTW, X-Rays go out the SIDES of the CRT, not the front. CRTs don't "use" X-rays, they are a byproduct - the radiation used to address the screen is more like very weak beta radiation, but it will NOT pass through the glass. And yes, it is KILOvolts at play around CRTs.

[@japanskakaratemuva5309]

And the crt really creates x-rays mostly only when it's powered on. After that it's negligible. But even then it's really not that big of an issue. Whole generations got to old age (yeah I'm old) beside turning these things on and off for quite a while.

[@noaccountification]

GPIB-USB are available new-old stock on ebay for example for less than $100, not 3K. The insulated thing you mentioned looks loke the high voltage transformer and it doesn't produce xrays. Nice scope!

[@thetriode]

That's a nice pick up. I have a Tek 455 that I still use and is awesome for basic and HF work.

[@mikegreen2079]

Just a thought regarding X-rays from a grey beard technician with over 50 years experience. The CRT produces a very small level of X-rays from the front, not really something to warn about, and indeed the black plastic part looks like the EHT transformer. I wonder if this might be a vector display, as used in some video games back in the 70s such as Atari Asteroid etc, rather than a raster scan display, used in CRT type televisions. The only part inside early colour televisions that was a serious X-ray hazard was the shunt stabiliser valve (tube) that kept the EHT stable thus preventing the picture size varying with picture brightness, I wonder if there is one lurking inside a piece of test gear of this quality. These used to be in a metal screened compartment with interlocks to shut the TV down if opened. To work live inside this compartment required the wearing of a lead apron, how times and technology have changed. As already mentionned placing the CRT face down can cause detritus from the cathode inside to fall onto the back of the phospor coating causing dark spots, that would really spoil a lovely scope. Nice video, keep them coming, thanks.

[@mp-ov9dh]

Great explanation!

[@uploadJ]

Raster - like TeeVee ... also accounts why there is a VGA output in back ... some of the HP 8560 series Spectrum Analyzer displays used vector graphics though.

[@RP6conrad]

I had scored a broken TDS 420A out of the dumpster in 2010. I managed to find the problem (a small ceramic capacitor of 2 €cent in the power supply), and it still works like a dream ! These scopes are build for eternity !

[@KeritechElectronics]

Hang on, we've got another Dave Jones here! Today In The Dumpster Room... Definitely a nice find. Tektronix always made great scopes, even if this one is nowhere even close to modern DSOs, it was the high end at its time. Definitely worth keeping and learning how it works. I've got a Tek 468 which is as old as me and is my favorite scope by now :). This DSO uses a kinescope type CRT, like you find in monitors or TVs. It uses magnetic deflection (that's what the yoke on the neck is for) and is indeed a vacuum tube... with a bunch of kilovolts plate voltage, so be careful around it. This tube is pretty short, takes half the depth of the scope's enclosure, but it was not a thing with analog scopes which use longer CRTs with electrostatic deflection. These tubes are a lot faster and suitable for viewing waveforms directly, in real time.

[@KB1UIF]

On the neck of the CRT are what's called field coils. They deflect the trace around the screen. Just like old TV's used to have field coils to deflect the electron beam around the screen. Don't rest the scope on its face, it's not advised.

[@sealiosprojects]

Is it ok to rest it on it's back? (Handle and screen facing up)

[@KB1UIF]

@@sealiosprojects Often there are feet protruding from the back of test equipment so you can rest it on it's back. It depends on the equipment. The service manual will normally include the correct method of dismantling.

[@alexcrouse]

I have two of these i found at a surplus hut and love them.

[@doogsm6013]

Download the operator and service manuals and watch some youtube videos such as eevblog and others on using a scope without blowing it up and it'll save you some heartbreak.. That crt tube runs on voltages in the tens of kV and the capacitors can hold a charge that will bite you hard also. Have fun and stay safe.

[@stevegreen5358]

I agree with you regarding the use of old equipment, but that's only 30 years old, so it's almost new! I just bought a CT52 miniature oscilloscope from 1952, so 72 years old - that's proper old. It's so much nicer to use kit that's got knobs and a CRT rather than doing everything through a keyboard and menus.

[@LawpickingLocksmith]

Never seen a Tektronix with a video connection. Now Rigol seems to have the crown of being connectable to a monitor.

[@AraCarrano]

Nice find with lots of the option boxes ticked.

[@uploadJ]

Got a TDS320 pretty much the same way - great scope and sharp CRT display!

[@enriqueolivares119]

If you find "RIFA" capacitors in the power input section, you should replace them as soon as possible. Best regards.

[@VasyVasii]

Have you determined the highest frequency at which a perfect square waveform can be accurately displayed on your equipment?

[@sealiosprojects]

not yet. the signal generator is a bit of a hassle to get working since it's so cheap

[@VasyVasii]

​@@sealiosprojects You can use the SN74LVC1G14 for 5,5V up to 200MHz with a variable sine wave generator

[@Roderick_Legato]

3:42 Your signal generator is saying 100kHz, your scope is showing ~5Hz. I suspect your timebase is set way too low and you are viewing aliasing.

[@sealiosprojects]

The gator clips that I was using in lieu of an actual connector were shorting on the generator

[@humgar]

I have a E2050A GPIB gateway (puts your GPIB instruments on the network) which I can sell it to you at $300 (I normally sell it for $400 on eBay) if you're interested. It's more versatile than USB which you're stuck with the drivers they provide.

[@tiagoferreira086]

What an amazing score! You maybe didn't realize yet how lucky you were to find it working and in a excellent condition with all those "accessories"! Damm i wish i could find "gold" like that... They still go for a non trivial amount of money on eBay.

[@sealiosprojects]

It was really surprising! I also saved 3 other oscilloscopes that were literally sitting in a dumpster the day before bulk garbage. You just need to look around and I'm sure you'll find something!

[@Chevroletcelebrity]

I need the images for those floppy disks if you could help me. I have a dolch pac luggable for my bench.

[@sealiosprojects]

When i go back home for break I’ll upload them to my drive and put the link in the description

[@Chevroletcelebrity]

@ ok thank you very much

[@Chevroletcelebrity]

@@sealiosprojectsdon’t forgot please

[@Multifuchs]

I like the old component test machines =) Very useful for my repair shop.

[@mikedjames]

Lookup how triggering works, and lookup aliasing. Nice tool to start learning about digital oscilloscopes and the technologies used. It only emits X rays if at all when its on, as the electron beam hits the phosphor , from the front of the screen like all CRT TV sets and monitors used to ( long way back the tubes in the CRT EHT supply also emitted X rays , before semiconductor parts were used) The glass has lead mixed in it for shielding . have fun! I have a couple of dumpster instruments thrown out by Nokia back in the 1990's, and a couple of oscilloscopes from Philips where I worked in the 90's. My day to day oscilloscope is a battery powered Fluke 95 which has clever electronics in it that means it out performs todays $250 USB scopes.

[@gerardzi7930]

This Scope Tektronix 420 IS good but you have a NVRAM inside for backup with battery ( Dallas backup memory) 20 years After dead..

[@ebayscopeman]

It looks like you had an issue with the scope triggering on the waveform. Normally the autoset should select the trigger channel. You might want to look into that. You can also manually set the trigger channel (which should be set to the same channel as the probe channel) if needed. Also this series of scopes is famous for having bad (phyiscally leaky) surface mount electrolytic capacitors. You might want to look at those aluminum cans on the main board and see if you see any liquid leakage. Mr. Carlsons Lab has a video on replacing those capacitors. You might want to look that up as replacing these will greatly lengthen the life of the instrument as the electrolyte from those caps can eat away at traces on the PCB and destroy the boards. Sam W3OHM

[@jtveg]

You bloody lucky bastard. I need to get back into dumpster diving, like I did when I was a kid. Thanks for sharing. 😉👌🏻

[@humgar]

Replace all surface mount electrolytic capacitors right away if it hasn't already been reworked. They are bound to leak at this age.

[@sealiosprojects]

When I get back home that's the first thing I'm going to do!

[@humgar]

@@sealiosprojects You got lucky that this unit turns on working. One can barely find a TDS 500A series that works right out of the box at this age.

[@steveharper2857]

What is a surface mount electrolytic? Do you mean through board electrolytic?

[@englishrupe01]

Ummm.....are you in your underwear?....lol. Anyway, that's a wonderful score to save from the landfill. Lucky man. Thanks for the fun video.

[@BuzzardSalve]

Maybe old by todays standards but a scope like this will get you out of trouble when debugging circuits ;)

[@uni-byte]

Looks like your triggering is not working properly. Maybe that's why it was tossed.

[@sealiosprojects]

It does work. The reason why it wasn’t triggering correctly was because I had accidentally shorted the pins on the signal generator while I was doing it in the video

[@uni-byte]

@@sealiosprojects It's great you caught that. Nice find. Hey, if you find another one send it my way! LOL!

[@andymouse]

@@uni-byte No! not him me !!!

[@uni-byte]

@@andymouse Too late Andy, I got here first!!!

[@andymouse]

@@uni-byte :)

[@Miller7747]

Here is a tip: Try not to run your camera on auto focus if you are to be moving in front of it, it drives the camera nuts, getting very confused about that the focus target is. You can use manual focus, if you know for example that the scope is 1 meter from camera, set manual focus to 1 meter. Very interesting video, keep up the great work.

[@darrenconway8117]

The label shows 20kV will be present on the CRT, even after it is switched off. Learn about discharging CRTs. Be very careful.

[@darrenconway8117]

@@inse001 Your saying 20kV is not dangerous, therefore it is safe. 20kV is never safe, and a 20kV shock would cause the body to jerk, and that might result body parts ending up where they shouldn't. You shouldn't be making comments like that. Some people might believe them.

[@inse001]

@@darrenconway8117 yes, I agree- I was referring to off-state

[@darrenconway8117]

@@inse001 Only safe if the CRT is discharged.

[@dachet10]

The Xrays come from the CRT not your little black tube. You need to learn how to use the triggering.

[@sealiosprojects]

Like I’ve said in the other comments, the gator clips were shorting. If you look at the thumbnail you can see them not shorting in testing.

[@gorak9000]

Those are not EISA slots, those are regular old 16 bit ISA slots. Also, you need to learn how to use the trigger!

[@sealiosprojects]

I said that they looked like them. The reason why the trigger wasn’t working was because after I tested it I took the signal generator apart and while recording accidentally shorted the output pins of the generator. I know how to use the trigger

[@splitprissm9339]

@@sealiosprojects actual EISA slots look quite different, more like AGP slots than ISA slots. They are also, amazingly, compatible with ISA cards (not the other way around). However, it is not something you would feel embarassed not to know about unless you worked or are working on high end 1990s computers.

[@coldfinger459sub0]

I have my fathers oscilloscope from my father‘s trade school in 1962 RCA and it still works all vacuum tubes

[@sealiosprojects]

Lucky!

[@horacepoon7044]

Tektronix is good.

[@sealiosprojects]

Very! That is why it’s sad that I had to pull the oscilloscope out of the trash

[@humgar]

Tek is horrible if you keep them long enough. Their designs age badly (like putting capacitor near heat sources) and it's a pain to service.