EEVblog #1366 - Mystery Bunker Item Teardown

Another mystery item from the storage bunker.

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[SeanBZA]

The big transformer is needed for the peltier element heaters, so likely there is a model which not only can heat the sample, but also cool it. You need a beefy power supply to enable fast heating, as you might have a sample barely defrosted, and need to get it to the reaction temperature for whatever reagents you are using, typically anything from 30C to 70C, plus you will have a cleaning cycle, where the heaters will need to get the cleaning solution up to 90C to properly scrub the cell windows clean. Same for the pump, massive with the need to pump the cleaning solution through turbulently for cleaning scrub action, but then has to flow through the analysis solution slowly.

Quick test to see how narrow the filters are is to shine light through the 2 close ones, you will probably find nothing out the other side.

Pump uses the motor, controlling motor speed and using the microswitches as limit sensors, so it runs one way till it hits an end, then runs the other way to the other switch, so you can have a calibrated volume of fluid per stroke, and also adjust motor speed to do flow control from fast to slow. Valve allows the sample chamber to be isolated, so the volume reacting will not move. Adjustable filters probably there so you can choose a band for the photocell to get the fluorescing of the sample, as these typically use a reagent that either absorbs light depending on the reaction, or which emit light when excited, so that you need to remove the excitation light to get a result that is the emitted light from the sample only. Thus 2 ranges, depending on the selected excitation, so the filter response does not allow light through giving an offset. Going to guess the entire sample volume is made from ground quartz glass plate and tube, that has been sintered together, and the sample tubes are PTFE that has been press fitted into ground openings, and backfilled with an epoxy for rigidity.

[st_us]

German Translation here: ELKO is not the capacitor Brand, it stands for ( Elektrolyt Kondensator) which means electrolytic capacitor. The Brand is ROE, Roederstein capacitors.

[PedroDaGr]

These instruments were used for running assays to measure enzyme levels in the blood.

The prism method you mention for selecting wavelengths is called a monochrometer. On that note, monochromters no longer use a prisms. Almost all of the monochrometers I have seen in recent years use diffraction gratings as they are smaller in size, cheaper to make, and have more consistent output. Filters are almost never used for spectrophotometers anymore either. You pretty much only see them in the cheapest of cheap models. That being said, filters are still heavily used in fields like flow cytometery and flourescent microscopy.

The filters are normally dichroic mirrors, bandwidth is often +/- 5nm or larger. The filter material isn't too expensive US$200ish (though for a medical device it will be much pricier).

[electronicsNmore]

Great teardown Dave! Love 80's electronic equipment. :-) 14:48 board discoloration is from the heat of the halogen lamp, you can see it at 13:50 exposing the exact area. The other areas of the board were probably protected by mounting brackets, etc.

[redtails]

Dave I really like this teardown. I work in biomedical sciences and this technology is something that I've used before. I'm puzzled by the 'flow' nature of this machine. Normally sample is loaded into a cuvette (a square glass/plastic/quartz container with a known lightpath and volume like 0.1ml) or a flat-bottom plate (like a 96 well plate). Light goes through it and transmission is measured, from which absorbance is calculated and expressed in log space. The use of plates may be too recent for this machine's age. Dyes specific to a compound are used on samples, which have a linear response to the absolute concentration of that compound, to be able to calculate the concentration from a standard curve. Though the 'flow' nature of this machine may be an indication of its age, as that would definitely be too time-consuming nowadays seeing the "2 minute" rinse cycle after each sample, jeez. A modern absorption/transmission UV/VIS plate reader can measure a 96-well plate (which contains the standard curve, samples with known concentrations, negative controls, and around ~30-40 biological samples in duplicates) in under 2 minutes, which would be 100-fold faster than this machine.

[ManuelHefti]

I worked in the lab for many years. What you basically can do is to measure concentrations of specific substances in liquids from the UV into the visual (sometimes also near infrared) range of light. Let's say your substance is red, it will block light from the blue and green spectrum range. The more concentrated your solution is, the less light of this range will pass. You'll need to do a calibration curve with different concentrated solutions in prior and you measure your sample then. Like this you can compare the transmission of the unknown sample against your calibration curve of the known samples and get the concentration of the unknown sample.

[tad]

The dark region on the PCB is likely from the light source. That would explain the unsharp shadow lines, it's from literal shadows.

[wilcostienezen]

Hi Dave, yes I know vitatron. It was a company 20 km from my home. There where 2 company's. One who is made pacemakers the other one manufacturer and distributor of clinical laboratory instrumentation. I worked there for 6 month.

[TheEPROM]

The proccessor board is also a keeper with all those lovely vintage chips on in.

[terminsane]

the Applied Science channel guy recently did a video on creating these filters. its worth checking out

[Ispike]

I work in a bioresearch facility repairing instruments, I've worked on a couple spectrophotometers. Be careful playing with old lab equipment, some of this stuff is very difficult to fully decon. There should be a biohazard sticker on this...

[omniryx]

Dave: "This is what I expected."
Translation: "I have no clue."

[jamesbrowne]

As you were posting this, I am working on a circuit board for a simple single wavelength version of one. No need to use our expense bench version for a one wavelength reading in a wet messy algae growing operation.

Could use a couple of those filters for my next project, a more sophisticated but hardened field instrument.

BTW the blank setting is to get a base reading for calculating absorbance.

[maxtorque]

You can so tell that Dave is not a mech eng watching this ;-)

1) Worm and wheels really only transfer torque in one direction, because there large reduction ratio and effective tooth angle prevent back driving
2) The micro switches and the shaft on the valve assy clearly read the VERTICAL position of the valve! ie the shaft moves up and down and not round and round!

[arthurnonimus]

Don't have a manual but these instruments usually use a reagent that is added to the sample which makes the analyte under test absorb the specific wavelength output as selected by the monochromator or filter. It's a UV-Vis/IR combined device and I believe was an instrument used for body fluid analysis. The functions on the front Factor, Standard, Reagent, Sample, and Blank are used for setting the parameters within the software - for example 20 times dilution factor, reagent 3 for analysis of blood enzymes (don't know the actual reagents), a set of known concentration standards and a blank for instrument calibration, and then the sample. The other functions are likely for titrimetric analysis as well as noisy/difficult to read samples.

[Ellipsis]

Those filters are definitely a keeper. A set of matched ones no less.

[protonjinx]

First you run a 'sample' of distilled water through to get a baseline of the lamp/filter performance which creates the "blank" dataset. Then you run through the sample and the difference between the "blank" dataset and the "sample" dataset is the actual measurement you want.

In the 90s I helped my uncle (chemistry teacher) to control a spectrophotometer via rs232 by means of some borland pascal for windows, to turn a manual single-value device into a scanning (sweeping the whole wavelength range) device. I was young and didnt really know what I was doing, but we eventually got it working fine.

[papaalphaoscar]

I worked with a more primitive single wavelength model for colorimetric assays. We used to put the sample manually inside a "tes-tuby thing" thing called a cuvette. Those were made of quartz way back then and we were constantly reminded that one would cost about half a month's salary. :-D

[Slide]

Hmmmm. “Tron” in their name, and a model called “MCP”? Coincidence? 😀

Great tear down Dave. Thanks!

[JerryBiehler]

The filters are dichroic, layers of material with different refractive indexes stacked and depending on the thicknesses and how many layers you can tune to filter whatever you want. Pretty cheap, the manufacturers cost probably 10-20 a piece and then they put in in a housing and sell it for a lot more. Still way cheaper than putting in a grating and the mechanism to control it, and you don't need calibration with filters.