EEVblog #1126 - Mystery Teardown!

What's is this obscure 1970's bit of kit from a big name manufacturer?

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[movaxh]

This is component of HP 3350 series, which is a lab automation system. HP itself also was a big player in analytical chemistry, especially chromatography and mass spectroscopy. But they were selling instrumentation, data logging, control, printing, storage, crts, etc, entire system as modular system, for other companies and to laboratories to build custom scientific equipment, both in chemistry, medical diagnostic, but probably also in other serious fields (physics, astronomy, etc).

[Chriva]

Looks like glass wool. I'd not scratch my balls after handling that if I were you :D

[JGnLAUOAWF]

Do a review of that screwdriver please.

[bobweiss]

This was a small part of a Gas Chromatograph setup. Used for digitizing the output from the detector.

[borkowsm]

I think that HP mount this crystal upside down for AU market 😀

[marklange]

Hi Dave, From what I have been able to find those 1852A’s were part of an HP 3352B Laboratory Data System, used widely in gas and liquid chromatography equipment. It had an HP “computer” if you could really call it that, with a whopping 24K of memory, and output to a plotter for accurate plots of chromatograph peaks. Used in everything from Medical research, drug testing, forensics, to oil and gas industry, and chemical manufacturing. High precision for the day, and HP apparently didn’t want anyone working on defective equipment (other than HP themselves) because you are correct about absolutely no manuals or schematics “in the wild”. That was pretty much standard practice for HP in the day. I hope this satisfies a bit of your curiosity.
P.S. I actually saw one of those in the early 1980’s in a Mud Logging Trailer at a 22, 000 Feet deep gas well drilling site in South Texas. It was connected to a gas chromatograph monitoring samples of gas coming out of the drilling mud that was pumped through the drill string then back up the bore hole into the mud pit. It was running in parallel to a Honeywell analog chart recorder, I guess they didn’t want to take a chance of the “new fangled” digital machine missing something.

[RuneTheFirst]

Capacitors: "Don't be vague, ask for Sprague!" (Their old slogan.)

[JimGriffOne]

Apparently it could be used as part of a gas chromatography setup - using the HP 5890 SERIES II Gas Chromatograph.

There is mention of a cable in the document I found:

Part number: 05890-60790 | Edge Connector: HP 18652A A/D Converter, 1V input

[Daveyk]

That RED "gunk" is high voltage varnish. We used to call it "glip" to lock in the pot adjustment so that it would not vibrate to a different value and you could tell if someone adjusted it.

[Goonygoon]

Heat resistant... insulation... from the 70's.. in the US.. That ranks up there on things I don't needlessly play with.

[JimGriffOne]

17:13 - I believe the "Start/Stop" button controls external equipment. It acts as a simple trigger to start other equipment connected to it.

[cuteswan]

I immediately thought the gunk on the pots was just fingernail polish: My father and his colleagues used to put a dab of red fingernail polish on the edges of trimmer pots – just like that – after calibrating instruments. Supposedly it kept them from drifting due to vibrations, especially in heavy industrial settings. The blobs held well enough for however many months, then broke away easily when it was time to re-adjust. I don't know if the vibration issue was a real thing, though maybe it was also a bit of a deterrent for customers to futz around with the settings too.
Thanks again for another fun & lively bit of education.

[jagardina]

Before the reveal I would guess some kind of precision data collection device. HP did a lot of automated test equipment stuff. We used a lot back at Bell for digital transmission testing. This seems to predate GPIB/HPIB.

[dvlachy]

Dave, I've seen one of these at a Garrett manufacturing plant in UK. It was used to sample analog output from a speed sensor of a turbocharger under test. I believe there was kind of primitive digital closed loop system with adjustable PID controller. The purpose was perhaps to control the speed under various engine loads and rpm. There was more HPs in the rack, but I remember this one only due to the fact it was 40years old A/D.

[laptop]

That old case is a giveaway if you have some of their other rackmount kit from that era.

[sandeepkerala]

This is the ADC used in old HP(now agilent) gas chromatograph. This is a ADC for calculating the peak area(flame ionization detector femto to pico ampere current converted to plus or minus 1 volt using a transimpedance amplifier and the same will be converted to digtal using this ADC box. Sampling can be done up to 32 hertz(more number sampling more narrow peaks can be detected). We inject a standard, calculate are under the peak then inject sample and compare the area under the peak to the standard and will get the quantity. The peaks are eluted as an order and its called retention time. With respect to the retention tie, qualification can be don for different materials. Now many manufactures have gas chromatograph including us :). Data apex clarity is an excellent product now a days...

[RuneTheFirst]

The Navy still had some of this stuff kicking around at their engineering station test facility in the early 90s. Long gone now.

[TheDefpom]

@ 11:30 I'm pretty sure they are just trimmers.

[sarreqteryx]

as mentioned already, it was used with a couple models of gas chromatographs, to provide a digital signal to computers. it was also used in industrial process control units, for much the same. I haven't been able to find much more than that. apparently, it was also co-produced by Agilent.

[genixia]

Given the age of that gear, I wonder if Bob Widlar had any hand in those National Semiconductor Op Amps. I note that the fixed resistors are all 5 band 1% variants. Note just how bad electrolytic capacitors are: +/- 20% when new. More like +10/-30% as aged. The metal film cap has to be the sampling cap. I'm not seeing any DACs or R2R networks, so we can rule out any ADC type that needs a DAC. The thermal insulation ensures that both power rails are affected equally by ptc/ntc component effects, thus preventing the derived reference voltage from drifting. The signal path will have been given the same design consideration.