Donated Eskalab Spectrophotometer

We got a free spectrophotometer lab instrument from the 1960s! It is a wounded beauty: it's devoid of any online information, is missing tubes, and one of the boards says "BAD" on it. Can we save it?
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[@davepost7675]

I guess I'll go to the store in 51 minutes and 29 seconds instead of now.

[@benjaminhanke79]

I think I skip watching 24h Le Mans for 51 minutes and 29 seconds.

[@jackb3493]

You still haven’t left yet, have you

[@supercompooper]

You see what I mean? These so-called pretend fans that don't even watch it two or three times in slow-mo 😮 😂😂

[@JSMCPN]

I hope you remembered to grab a spare 6-pack of dynodes!

[@alanclarke4646]

Master Ken's reverse engineering skills are awesome, just like the team's ability to restore these instruments. But, imo, the most remarkable thing is Marc's ability to find suitable replacement parts.

[@terrygains8327]

Re: The "Shelf of Shame". Thanks for motivating many of us to attack incomplete projects Marc.😃

[@p.j.wilkins1321]

Shelf of shame? Adorable. I'd like to welcome you all to my "what seems like half of my f'ing house" of shame... 😄

[@Brice23]

Up at four AM, sleepless.. what better time for a lesson about an old spectrophotometer.

[@grant2053]

Felt this in my soul....

[@picrijogil]

We did a chlorophyll experiment in high school with a single path spectrophotometer from the 50s, so apart from the endless manual writing down of spectra, there was the having to do it twice because you needed the reference absorbance at every wavelength as well. A tip for better calibration: you really can't adjust this thing with the room lights on and the covers off - especially at the higher end of the absorbance scale. The PMT is sensitive ... . And for proper measurement, you need a cuvette in the reference path as well, as well as a black cap that is missing, both over the sample and the measurement cell, to exclude ambient light.

[@docteurlowbat]

Yes, must be closed. Reference cuvette is needed. Must be filled with the same solvant. To folow Beer's Law, measurement at max absorbtion (430 or 660 nm).

[@pdc023]

It's been many years since I worked with one of these (Perkin-Elmer, not Smith-Kline, and a single path instrument) in an industrial setting, but you are correct, You need to zero out the instrument on an empty cuvette, And yes, ambient light needs to be eliminated. This was not a problem with an assembled machine since they were designed to be "light tight".

[@peterweingartner4364]

One of the things I love about your channel is getting to see the clever engineering that people did before microcontrollers came on the scene.

[@oldblokeh]

In (I think) 1979, HP turned the world of UV-VIS absorption spectrophotometry on its head by introducing the HP 8450, made by HP Scientific Instruments Division in Palo Alto.. This used a grating and a photodiode array. So the grating was stationary and the dispersed light fell on the array so you could measure the absorption at all wavelengths pretty much simultaneously. The HP 85 was used as a controller via HP-IB (GPIB). Since you already have an HP85 you really should look for an HP 8450. It led to the development of diode array detectors used in liquid chromatography..

[@douro20]

I think the 8450A had what was basically an HP-85 built in to it?

[@oldblokeh]

@@douro20 You may be right. I could be confusing it with the 5970 mass selective detector which, I think, came out about the same time.

[@CuriousMarc]

Oh the HP 8450 is a huge boy!

[@antronargaiv3283]

Photodiodes *usually* have a pretty significant sensitivity vs wavelength curve...so you'd need to calibrate that out...as obviously HP did.

[@silverXnoise]

There’s a unit on eBay right now for $585 AS-IS, showing a photomultiplier failure, comes with seemingly functional 7470A plotter.

[@sittingstill3578]

Wow! Marc upgraded his gear to 4K. :D So cool, thanks for giving us even more visual fidelity.

[@CuriousMarc]

I did! This was my first try with my new 4k camera (a Sony FX-30), and you can tell I’m struggling with it: bad focus, bad color balance, and bad sound periods, but I’m getting better at it by the minute as I am completing the setup. It’s an amazing camera. And the sound is going to be much better too.

[@MarcelHuguenin]

What an absolute masterful reverse engineering. Epic video, you guys are automagically the best!

[@Filippoilcane]

Best channel in yt

[@CapitaineBeaudet]

Quel suspense..! Au début, vu le manque complet d’information, je n’y croyais absolument pas. Et plus la vidéo avançait, plus tout s’éclaircissait grâce à votre assiduité. Quel épisode remarquable.. merci.

[@timwilliscroft9615]

And if you attach a rubber wheel with a servomotor to the wavelength knob to motorise it, and read the analogue value through the test port, it can plot proper spectra. As an HP-IB bus peripheral, of course.

[@mumiemonstret]

No motor needed. No digital mumbo-jumbo. Just put a potentiometer on the wavelength adjustment and connect it, and the transmissivity output, to an analogue xy-plotter (HP of course!). Very simple mod.

[@pa4tim]

Very impressive restauration, well done. Keep those tubes in the dark. You can damage them in bright light. I have a tube connected to a PSU and even a led at 10uA gives enough output to get a voltage reading from the tube. I think the coloured "tiles" are for calibrating or as a compare to the sample. But I'm not an expert, I just so want something like this machine for years. They are technical so cool. For the old caps, test them at 120Hz and use DF (tan d) instead of ESR. The datasheets of elco's only use DF. In the 60's 1kHz was the most used frequency. But most important parameter for old caps are DC leakage, they tell you if the oxide layer is thick enough. (My hobby is restauration of component measurement bridges)

[@skinnymalink72]

I remember seeing my dad use this instrument in the hospital lab in the 70s when I used to accompany him mostly when he was on call. I found the big dial on the eskalab fascinating.

[@Scrizati]

As someone who uses this kind of equipment regularly it is fascinating to see how it used to be constructed vs the 90s equipment I was trained on and vs the modern equipment now

[@zebo-the-fat]

Very nice, brings back memories of my first job after leaving school, testing paracetamol in a pharmaceutical lab (absorbing UV at 243nm)

[@JessyP-u6q]

Thank you

[@MeriaDuck]

That enormous meter 😍

[@alanclarke4646]

Yeah, it's a thing of beauty.

[@zero0ryn]

Reminds me of my Father's AVO Mk 8 multi meter.

[@hapskie]

What a wonderful quirky design, getting all nostalgic. Getting a morning coffee and going to enjoy this for almost an hour!

[@NahNoThankYou]

Marc and team - your contributions to the world have truely changed it. ❤

[@chemicaldexter]

its not a cells suspension - the heated compartment is for incaubation: eg. you have separeted the cells from the blood (and other stuff) to get the serum, then eg for glucose you ususallly mix 1ml of chemical reagent with 10µl of serum, put it into the heated area for 10 min at 37°C then measure usually around 510nm the Absorbance

[@XMarkxyz]

I'll trust someone who has chemical in his name on this

[@agranero6]

Ohhh those dichroic filters are cool, choosing the correct layer number, thickness and refraction index of each layer you can made them notch band, pass band, lower band, high band, wide or narrow band, very narrow band (which is the case here) to any wavelength you want.

[@navex4786]

Nice one! In 1974 I joined the then Philips owned Pye Unicam (Cambridge UK), producer of rival spectrophotometers to the one above. By that time the output display of choice had moved on to 7 segment LEDs rather than meters but we did get a meter equipped one back with an odd fault. Randomly the needle would momentarily flick over to 3A and back. Having ascertained the light input was stable during the event and that it was only the PMT output that dipped, the PMT and it's associated electronics were changed to no avail. That only left the optics. It was only when the monochromator cover was removed that the spider living within was discovered. . . Keep up the good work! D.

[@jurjenbos228]

I'm especially impressed that you are not intimidated by the complexity of this project

[@campbellmorrison8540]

Guys here I am fighting my way through trying to fix an old monochrome CRT monitor with no information but I do know how it works basically and here you are fixing something more complex and working out how it works as you go. I wish you were here :)

[@thomasives7560]

A fun mod to that might be a motor that scans the wavelength and produces a spectral response. Modern devices do that automagically, but the accuracy of this unit might produce a much more authentic response, since the filter is single-wavelength. Many years ago, I worked in a university science shop where they "scanned" materials based on spectral reflectance with a similar device, and somebody there wrote a paper on it - the concept was the same, scan a filter over the range and digitize it in the frequency domain. Anyhow, I really enjoy the chill of your content, it is always a Sunday treat! Cheers!!

[@VintageTechFan]

Having repaired/serviced a much more modern / automated absorption spectrophotometer at work multiple times, this is exciting to see.

[@malcolmgibson6288]

Sunday morning lazy day with Curious Marc video. Bliss.

[@bradnelson3595]

It's just a fancy Gin-o-meter. Love it! Great presentation, guys. Amazing knowledge on display.

[@wa4aos]

Congrats on the repair and cal. Perhaps, part 2, where practical analyses are performed for qualitative, quantitative or verifiable results. More on actual applications please. Great video !

[@kevinmerrell9952]

Amazing instrument. Thanks for rescuing it!

[@chemicaldexter]

Small Correction: cells are not measured with this kind of innstruments, in the medical world its parameters like Cholesterol that are being measured with this, ususally the cells are separated before measurement. other fields outside medical are water analysis some parameters in food analysis etc.

[@senorcapitandiogenes2068]

I assure you, we measure cell density with these kind of devices regularly

[@chemicaldexter]

@@senorcapitandiogenes2068 I work in IVD - never heard of UV-VIS used for cell density. In Hematology, you use this pricnciple ony for HCT, the rest is determined by Coulter Chamber

[@fburton8]

Male fertility is often assessed by estimating spermatozoa concentration using a spectrophotometer (or at least it used to be).

[@fburton8]

When Marc refers to “the cell” I assume he’s talking about the sample vial/cuvette or the space that it sits in.

[@michaelallen1432]

Yes, you can measure all sorts of things like blood glucose, bilirubin for kidney function. There are various clever methods that were dreamed up over the years. Often things that do not have distinctive spectra are reacted with something and the product can be detected.

[@AppliedCryogenics]

Thanks for opening it up and showing us all of the interesting "thingys". ❤

[@cbmsysmobile]

Neat little device. And one I could almost understand the circuitry for.

[@analogdesigner-Jay]

I'm watching this at 4AM and this turned out to being a "Case of Beer" project. Nice work!

[@SVanHutten]

Great job on a beautiful and very cleverly designed instrument. The party trick for changing the absorbance scale on the meter is something I had never seen before. And the sheer _size_ of that meter!

[@beatadalhagen]

Beautiful! I think we had a machine much like this in the back room during college, but never got to use it. And the gain control for the reference sample. I need to remember that.

[@BartManNL]

Nice memory from lab school, somewhere 1986-1987-ish. I was at the "chemical" department but we also had to do "biological" labs. One of the tests was measuring the growth of bacteria by measuring the turbidity of the growth medium (not exáctly what these photometers are designed for, but it works just fine). The lab assistant was convinces that is was broken because it couldn't be zeroed, but we saw immediately that the mechanical lamp slit was totally open, they turned the wheel the wrong way. Within a few seconds we had the instrument zeroed. Comment of the lab assistant was "chemistry students..." The current photometers work with autozeroing, auto wavelength, auto everything. It has less charm that way...

[@gordonwedman3179]

I imagine back in the day an instrument technician would have spent a lot of time fixing this unit. Great job team.

[@alexlefevre3555]

Yet another endlessly fascinating CuriousMarc banger. I clearly remember color banding through different materials in chemistry class a few decades ago. Seeing the process performed mechanically is such a testament to engineers of the time. Nice 4k upgrade, my friend!

[@ntsecrets]

30:18 (Real Genius quote) Always check your optics!

[@glennbruner7504]

Excellent look at a very unique instrument. You and your team are so awesome! Your videos are my always a must watch.

[@Peter_S_]

Photomultipliers have a sad Achilles heel which is helium contamination. They tend to have high vacuum and over time, helium will leak in through the glass and stop them from working. Be very cautious when working with them because they dislike light when they're off and light will wreck them instantly when they're powered if you optically overdriver them.

[@benjaminhanke79]

Wait, are you telling me a sealed vacuum tube is a way to salvage traces of helium? And why not Hydrogen?

[@Peter_S_]

@@benjaminhanke79 I couldn't tell you why hydrogen isn't a problem but all you need to do is search for "photomultiplier tube helium". Hamamatsu's data says, "To reduce the effects of helium gas, it is best to store the photomultiplier tube in helium-free gases such as argon gas and nitrogen gas."

[@davewright3088]

Bravo..! I consider Marc, Master Ken, and all of the tribe of the restoration team to be the professors in my post-graduate self education. Best morning coffee videos to inspire a day...!

[@MK-tx1nd]

for the best accuracy of your calibration solutions, use a scale. You can weigh far more precise, with less expensive equipment, than working from volume (which always carries temperature errors- volume of container(dVdT); density of liquid(dVdT); ect)

[@growingknowledge]

That was a lot of fun. Well played Gentlemen.

[@ireallyamrumi]

As a biologist I cheered for this incredible crossover episode! Nicely done!!

[@AL6S00740]

Damn. I really want to get taught by all of you ! The methodology and understanding and explaining is amazing !! I hope kids , grandkids really take lessons from you because you are one in a billion ! Thank you for the amazing video :D !! like always

[@maxheadrom3088]

From the makers os Eskalator! Eskalator - takes you to heaven and back ... and you don't even need to move your legs.

[@acmefixer1]

Those bad capacitors - I could troubleshoot that problem. But the rest depends on other physical things that I would not have any experience with. I realize that Marc and Ken took several days to develop a schematic and diagrams. One has to approach this systematically. And that's probably the most important thing I've learned from watching Curious Marc's channel. Thank you so much.

[@ShukenFlash]

I've used a more modern version of this to evaluate the effectiveness of filters at removing dyes or pollutants/sediment from wastewater. Really handy little machines.

[@hachimankmd5843]

I have one such spectrophotometer which I literally pulled out of someone's hands. He was going to throw it away and I at the time needed a photodetector covering the near IR spectrum. I was building some spectrophotometer of my own for my school work and was broke as hell. Took it but it turned out to be designed for the UV-Visible range. I promised to repair it. It's being lying on my shelf with other poor electronics for the past four years still waiting for the repair. I guess this 51min29s will give me the boost I need.

[@tekvax01]

Another amazing repair video! Thank you everyone!

[@salan3]

I used to work for Varian Inc on amongst other things UV-vis/NIR spectrometers(DMS range and Cary range).

[@carpetbomberz]

Dilution calibration for the win. And I had forgotten a quick/easy way of extracting chlorophyll, oh those were the days. 👍

[@lucianchauvin8587]

Such an amazing video as always. Thank you!

[@XMarkxyz]

I know it's just the camera flattening everything but him pointing at the photo chopper got me really scared of seeing it become a finger chopper

[@diabolicalartificer]

The missing 10/11 pin tube could be a relay. Have you got DC on pins 2 & 10? Amperex delay relay valves are usually paired with a bigger power relay as in all the Tektronix 500 series valve scopes. The delay relay - K1 switches on after X seconds, switching on the power relay - K2 which in turn cuts DC to K1 & also switches on other voltage rails.

[@wacholder5690]

That happens, when people take science serious ... ! Thanks for showing. You learn a bit new every other day. Particularly with these videos. Even about the most exotic and aside sciences. 🙂

[@RobSchofield]

Excellent!

[@Runco990]

That was far more interesting than I expected!

[@jlwilliams]

You know it's going to be a good day when CuriousMarc pronounces something a basket case, but then you check and see you're only 1/3 of the way into the video…

[@unmanaged]

I still have that early digital scope that needs a good home from the director of DEC...

[@radioaktiv2531]

Finally! A CuriousMarc video I can understand. I use UV/Vis spectroscopy in the laboratory.

[@ozimerman111]

You guys are fantastic. Thank you!

[@AlejandroLopez-qd3xm]

Nice spectrophotometer debug!. I use to assemble and calibrate a very similar instrument back un the 80's, it was a lite mire modern than yours, crammed with op amp and a microprocessor controlling the monocromator . It was a lot of fun

[@albertsandberg]

Don't worry about the experiments. That's Ben's job over att Applied Science :D Excellent video. The longer the better.

[@michaelallen1432]

It looks a lot like the classic Spectronic units. I have one from the 80s that is quite similar to that one. They are amazingly sensitive and can be used for a wide range of analysis. They can not only be used for simple absorbance or trans instance tests but if you have an analog output, or tap off the detector you can use a strip chart recorder or digital acquisition system to analyze a rate that a reaction is proceeding which allows you to sort out things. A lot of clinical analysis used to use them before they changed over to specialized instruments using immunoassays.

[@y2kkmac]

Ooh fun, optics!

[@bigsarge2085]

Always interesting!

[@AsbestosMuffins]

you'd likely have a bunch of standards stored in the side slots as well as samples. on a digital one of these you'd setup a calibration curve in software but you can do the same thing using an analogue instrument like this

[@alvarobravo177]

Impressive restoration. I think you should cover the cuvette when doing the readings to avoid the ambiental light messing up

[@anthonyshiels9273]

I used one of these as a University Student in the early 1970's. Ours was a Bausch + Lomb. Nowadays they make Eyecare products and they have a Manufacturing Facility in Waterford, Ireland. I don't think that their Spectrophotometers were made there.

[@MichaelOfRohan]

51 anda half seconds of pure internet goodness

[@ellindsey000]

I work for a company that makes what are essentially the modern versions of these same machines. It's fascinating to see how these old versions of these machines worked. Although we still do sometimes use photomultiplier tubes in the modern versions.

[@jobkneppers]

Very very fine job! One suggestion; the plastic lamp mount will not survive the heat. I would exchange it for a ceramic one used for halogen lighting. Thank you all. Best! Job

[@jamesbrewer3020]

Thanks for another great vedio'

[@michaelcherry8952]

5:25 I have a 1936 RCA console radio (9K1) with several shortwave bands that changes the dial calibration for each band similar to this. Called the "Magic Dial" of course!

[@paulbyerlee2529]

I picked up one like this at the tip back when I was 17 many moons ago. I was too young and stupid to realise what I had this was before the internet had really taken off. Sadly I no longer have it in my possession. Ah the follies of youth😢

[@andymouse]

Awesome...cheers.

[@radarmusen]

Gin for calibration of beer laws.

[@user-nd8zh3ir7v]

wow full of surprises

[@SidneyCritic]

I remember a old spectrophotometer on American Pickers, but it looked like a brass telescope - lol -.

[@DavidBuckley-u1u]

A Nyone who was a hospital lab tech in the 70s will be very familiar with thesr machines.

[@aaronr.9644]

you guys are well in your way to building your own space program :)

[@MarcoTedaldi]

When we used Photomultipliers in our two photon microscopy setups, we were told to keep the Tube in the dark because the sensitive surface might get bleached out in daylight. Was this issue overblown?

[@andymouse]

No! you should but at this age ! not so bad:)

[@darrendunphy6041]

There is an error in the video; concentration is proportional to the absorbance, not the log of the absorbance. Absorbance is -log of % transmittance, so that may be where the confusion comes from.

[@TechGorilla1987]

Optical?! Who could have seen that coming?

[@alanclarke4646]

Please don't do that again! 😂😂😂

[@genetomblin2883]

The TO8 case transistors really date this to late 50s early 60s

[@vanhetgoor]

I think it is even more difficult then what was shown here. I assume there is a book somewhere with tables in it, translating the ciphers on the scale to useable numbers. This instrument must have costed a small fortune and I guess it could only be operated by extremely well trained technicians.

[@tengelgeer]

19:00 Old caps that look like overachievers are most of the time a sign of a cap with a low series resistance...

[@zero0ryn]

Mr Carlson teaches that over achieving caps are always a result of being leaky.

[@rickhole]

Gotta love that "bad" transformer. Nice "save". I thought you might put a sample of beer in for a test.😀

[@marcusdamberger]

I think it was just referencing the entire board, not the component the sticker was put on; just a convenient flat place.

[@AndyHullMcPenguin]

When you find yourself an instrument you can calibrate with Gin, all is well with the world.

[@LaLaLand.Germany]

For being out of Your element Y´all did (as always) a marvellous job. I enjoyed the elevator music parts, more channels should do that. This thing is a beauty, I love the scale size. Take a look at the German made Grundig(Sennheiser) RV55 voltmeter. Not only is it pretty but it has a 1mV scale up to 300V, up to 1Mhz sinewave. I´d love You to do a bit on that, such few good intel is in the net- I´d like to have someone make out the internal calibration. After I restore it I´d like to actually use it.

[@wolfgangrichter6088]

Well, a spectrophotometer is a nice thing to have, but today you need a gas chromatograph and a nuclear resonance spectrometer, at best a gas chromatograph coupled to a nuclear resonance spectrometer and, if your chemicals are spread spatially, a scanning electron microscope coupled to a soft x-ray spectrometer that can tell you the spatial distribution of the chemical composition of what you are looking at is a must have. In the past, the little chemist's home lab consisted of a bunsen burner, a water suction pump, some glass work and a small chemistry kit only, but now the above mentioned instruments is what you need at least. The times, they are a changing.

[@JessyP-u6q]

Thank you sir

[@daylechipps7124]

Thanks!

[@CuriousMarc]

Thank YOU!

[@p.j.wilkins1321]

I was not expecting Philomena Cunk to be referenced at 1:51

[@TechGorilla1987]

@11:08 - That detent mechanism though - a proper "cahunk-cachunk" ball bearing mechanism. What pure electro-mechanical (p)orn.

[@Izephyr1]

Nothing like unwrapping the asbestos rag around a fresh photomultiplier tube

[@m.k.8158]

those are NOT asbestos, they are made from multiple layers of soft paper, possibly with some padding between the layers. Asbestos would have no benefit in this application.

[@anorderedhole2197]

Measuring absorbances is still going strong in the life sciences! Machine was probably made for bacteria cultures as OD values go to 4.

[@maxheadrom3088]

Jokes apart ... I believe those ColorMunk display calibration devicese work like that - with a monochromator to measure the intensity of colors.