EEVblog #628 - Tektronix 213 Vintage Portable Oscilloscope Teardown

[M0BSW]

 I hope you put it back together,and it's a keeper in your lab.

[reinhardz]

Hi

Thank you very much for that great teardown.

Just one remark: U260 is not a custom made TEK chip. It was manufactured by MOSTEK; its data sheet can be found

here: http://www.datasheetarchive.com/dlmain/Databooks-2/Book271-73.pdf

HTH and best regards

reinhardz

[free_electron]

1973 was a good year, the year when I was born That's the schematic on the tekwiki:

http://w140.com/tekwiki/wiki/213

I think the 8038 is not a custom Tek chip, but from MOSTEK, the same manufacturer that produced the 6502 CPU. But I can't find it on the web, and interesting that the logo is different from other MOSTEK chips I know ("MOS" instead of MOSTEK). Maybe a really old chip.

MOS is not the same as MOSTEK.

MOS was an independent company , got borged by from commodore and then spat out again and finally sold its fab to someone who ran it into the ground and left a big stinking chemical cesspool...

MOSTEK was a bunch of runaways from TI. they were borged by ST. some of their products still live on today

[N2IXK]

I did a doubletake when I saw the prominent 8038 datecode on that chip, as well.

The 8038 I am familiar with is the ICL8038 from Intersil.  A function generator/VCO chip that I played around with as a kid (Radio Shack used to carry them and the Mims notebooks featured them).

[Fraser]

I used to collect these Tektronix handheld scopes and have a few working examples 

I can confirm that the probes for these oscilloscopes were permanently connected to the unit and had a small in line coaxial connector in case the probe needed to be changed. I managed to source a pair of spare probes for my units at a reasonable cost. They are as rare as hens teeth now. It is important to be aware that the input to the oscilloscope channel PCB is a non standard impedance and the scope probe cable was a very specific length to match without the need for a compensation trimmer. Fitting a standard oscilloscope probe designed for 1MOhm inputs is not supposed to work with these, though I have not tried it myself. The input compensation would be incorrect and the 10X division ratio wrong.
This is incorrect .... probe is 1MOhm X1 type with no internal resistor fitted.
I own a 213 in my collection but it needs a tidy up and every knob has been robbed from it 

The 213 was a very special model as it contained a very accurate meter that needed to be calibrated by Tektronix themselves. The calibration process was said to be too challenging for generic calibration houses. The calibration techs considered these units a PITA to work on.

I own a 211, two 212's , a 213 and a 222    They were not cheap when I bought them but prices have increased significantly as they became collectable. Bandwidth of all but the 222 is tiny by modern standards at around 500kHz. Still love them though....almost pieces of art !

Aurora

[Fraser]

The 212's and 222 are in the lab but I dug out my 211 and 213 units for some photos. I also found part of an original probe assembly. The X10 divider tip is missing from this one. I have two brand new assemblies so this is really just a spare cable. The coaxial connector may be seen at the end of the probe cable and this mated with a short cable within the scope.

It is interesting to note that my 213 has also had its probe cut off and a BNC plug attached. Such action appears to have been born out of desperation when probed stopped being available and users were not aware of the compensation and non standard divider ratio built into the probe & cable assembly.
Edited as incorrect.
The 213 is as bought from Israel and needs restoration. I just don't have the time to track down all the missing knobs at the moment.

The 211 is without mains lead and probe at the moment as I rarely use it. The two 212's are in 'as new' condition as they came from unissued Military stock. The 222 is also in great condition but all these scopes are only in my ownership because I like the engineering that went into them. As practical scopes they are totally obsolete museum pieces.

Aurora

[Fraser]

I just found the missing probe head.

Ooooops I got it wrong regarding the probe .... the probe is clearly marked 1 MOhm so is not likely to be a X10 probe    My mistake.

Maybe the impedance issue was with another TEK scope probe assembly. My memory fails me these days. I will need to check the service manual. I have service manuals for all of my 2xx series scopes.

Just measured the resistance of the probe head.... Zero Ohms so no internal resistor is used. Probe is unique only in its odd shape to fit the 2xx series. I will delete my comments regarding the probe in my previous post as it is obviously incorrect.

[Jay_Diddy_B]

Hi,
It is nice to see that Tektronix did not copy the power supply design from the 211:



The 211 power supply has some innovative features:

1) The batteries are on the line side of the isolation barrier.

2) A capacitive dropper capacitor is used to set the charging current. C210 or C212 is selected for 220V or 110v operation. There is a procedure in the manual for changing the values of these parts for different line voltages and frequencies.

3) The batteries assemblies are a total of 10 NiCad batteries.

4) Quite often dead scopes can fixed by replacing the batteries.

The Tektronix 214 uses a similar power supply design.

I am not a big fan of this power supply design.

Regards,

Jay_Diddy_B

[Fraser]

Totally agree regarding the 211 power supply. When I first saw it I thought it was damned dangerous. We used to call such power supplies 'infinity' PSU's as they used capacitive reactance and read open circuit if tested across the input. From memory, the batteries were a significant part of the smoothing and regulation in the 211. Operating it without batteries fitted was not recommended.

As a piece of trivia for readers.... When I bought my 212's, I wanted the service manual so I ordered a scanned copy from a reliable supplier in the USA. The CD duly arrived and I opened the PDF. Imagine my surprise when I read the title page of the document that stated that it was a manual for the TEK 212 ... which formed part of a surface to air missile system 

Imagine if someone had checked the content of that CD as it entered the UK ....... I may have received a visit from Special Branch to explain my interest in SAM systems ! The manual was actually a copy of the NATO maintenance document for the oscilloscope as it was part of the toolkit for a SAM system. Field engineers would have likely been very pleased to have such a compact oscilloscope for diagnostics, but it isn't something that would, itself, be field repairable. Both of my 'new' 212's came from MOD surplus and had the NATO stock number on them, so they may well have come from such a SAM toolkit.

Aurora

[EEVblog]

I loved the curved traces.  Where they all curved because they were probably HAND drawn by some graphics artist on a big drafting table and not by computer?

Likely used Bishop graphics tapes or some such. Maybe at double size and then photo reduced.

[TheRuler8510]

Dave,

To answer you question on how late the 213 was sold, my Tek catalog from 1986 has it listed, but not the 1990 catalog.  I don't have the in-between years. So as least as late as '86.

Nice Teardown!

From the catalog (1986):

[N2IXK]

According to the excellent video linked above, Tek's PCB layouts were done with tape at 4X size, then reduced.

[vk6zgo]

Recall the classic 70s sci-fi series Space:1999?
It began running in 1974, and had cool technology including the Comlock:

The one on the props were static pictures/slides backlit.  And they used a Panasonic TR-001 portable TV set for the closeups, it was a big bigger.

http://www.tvhistory.tv/1974_Panasonic_TR001.JPG

But still, I can only imagine how Panasonic managed to make a TV that small back in the early 70s.

CRTs can be made as small as you like!
This,of course,reduces the power requirements,so you can use smaller parts.

I remember having to replace the tube,reconverge, & set the colour balance on a very small Sony Picture Monitor which we used in the TVW7 Chopper.
I think the tube would have been about 64 mm across the diagonals,or thereabouts.(Yes,it was a Trinitron,& magnetically deflected).

This was in the mid '80s,but from the type of parts used,I would place the year of manufacture in the 1970s.
It had all the circuit boards mounted round the tube,making it a sod of a thing to adjust.

Vibration problems in the helicopter meant I had to pull it apart & try to make the boards as secure as they originally were ------about three goes to get it right!

The viewfinder monitors in tube type portable cameras were even smaller.
.

[Legit-Design]

I loved the curved traces.  Where they all curved because they were probably HAND drawn by some graphics artist on a big drafting table and not by computer?

Likely used Bishop graphics tapes or some such. Maybe at double size and then photo reduced.

We found this gem in A Manual of Engineering Drawing for Students and Draftsmen, 9th Ed., by French & Vierck,1960, p. 487.

Printed Circuits allow miniaturization and the elimination of circuit errors—advantages that cannot be obtained by other methods. Once a pattern or suitable design is established, preparation of a black and white drawing can start. Scales for reduction, for example, 4 to 1, 3 to 1, or 2 to 1, are used. To insure sufficient bonding area of the metal laminate during soldering operations, lines should not be less than 1/32 inch in width when reduced. Line separation should never be closer than 1/32 inch on the final circuit. Figure 19.24 illustrates the drawing of printed circuits.

http://www.evilmadscientist.com/2013/how-printed-circuit-boards-are-designed-1960-edition/

Is there any episode about this? I think it's been mentioned once or twice, but never in detail.

[mswhin63]

Nice teardown, I used to use this in my apprenticeship back in 1980. It was still a beauty in that day. Handy while working in North West Oztralia.

[vk6zgo]

Just a quick Q....

How does this vintage "mini" Tek compare to the modern Chinese "pocket" o'scopes?

Yeah .... I know I'm openin' a can-o-worms here ... but just to be clear:  let's forget the novelty/collectibility factor and concentrate on real/regular bench or "portable" use. Think: PERFORMANCE and ACCURACY and ERGONOMICS.
I think true portability issues like battery-use and "size-/weight-class" can also be neglected.

It is an Oscilloscope---I'm not quite sure what the other things are!

[tecman]

I own a fully working, nearly mint 214.  The 214 is a dual trace, 500 kHz storage scope.  Although limited in bandwidth, for audio, control systems and other lesser dynamic systems it is a nice little scope that goes down to 1mV/div.  The only thing I have done is replace the batteries.  Storage (non-digital, based on a special CRT design) is a nice, and today unique feature.

As stated, the original probes on these series are hard wired in, and the BNC jack on the tear down was a user mod.

Although not pocket-able, they certainly were portable. 

paul

[German_EE]

Has anybody considered how the digits are displayed on the screen? I have a few ideas using large EPROMs and DACs but these are obviously incorrect as Tektronix managed to do the job with only a few chips.

[mikeselectricstuff]

The viewfinder monitors in tube type portable cameras were even smaller.

[mikeselectricstuff]

Has anybody considered how the digits are displayed on the screen? I have a few ideas using large EPROMs and DACs but these are obviously incorrect as Tektronix managed to do the job with only a few chips.

It looks like the first chip was designed to drive a seven-seg display, and you can see how the digit selects are used to generate different X offsets for each digit, so the second chip will only be doing a single digit. Could be mostly a ROM+simple state machine.
 

[Richard Crowley]

If Dave had been able to complete the dissection of the input module, we would have got a better view of that cam-operated rotary switch.
Those things were just brilliant, IMHO. In some cases a very long shaft off the panel knob, and extending well back into the bowels of the gear.
They had little gold-plated leaf switches soldered directly to the PC board (much like those inter-board sockets). and then a custom-molded cam on the shaft.
As you rotate the knob, various switches on the PC board would be opened or closed depending on the shape of each cam segment.

As I said IMHO, truly brilliant on SEVERAL levels.  Hats off to those Tektronix designers back in that golden age.
As I drive by the Tek campus these days, it is a mere shadow of its former glory. Many of the buildings seem to be sold or leased to others.
And their custom, in-house semiconductor fab was sold to Maxim who probably still makes custom parts for Tek and others.
Here is a screen-grab from Google Maps street-view....

[13hm13]

I've gotta few Tek's from the mid 70s. Very durable and reliable (not surprised that Dave's unit still works)... common problem is open/shorted tant. caps. Often that's all that's wrong with eBay vintage "dead" Tek's.

That PCB is very neat and clean ... how was PCB assembly done during this era ... by (very steady) manual hands or some vintage automation (pick-n-place)?

[99tito99]

Great teardown, love the old school stuff.  Interestingly, earlier this week I went to a university surplus auction and bid on a pallet of lab equipment, power supplies and a Tektronix 577 Curve Tracer Oscilloscope with the 177 Standard Test Fixture (the whole pallet was $140 US).

And, it appears to work a treat:



The date codes are early 1989.







Cheers,
Mark
***********************

[craigh]

I used a 213 back in the early 1980s when I was an electronics tech working on ships.  It got dragged everywhere from down in the ship's bilge to all the way to the top of a mast.  Weighed a ton though, for it's size.  If I remember correctly (and that was a long time ago) I think it was powered by gel cell batteries.

[cloudscapes]

That thing is just adorable! Would pair well with my modular synth!