EEVblog

Old school, they don't make'em like this any more.
Teardown of the HP 3785A Jitter Generator & Receiver with beautiful HP bubble LED displays.
Forum: www.eevblog.com/forum/blog/ee...
#Teardown #Vintage #HP
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[@awfulinternet]

Love old HP science equip. Works of art and engineering.

[@TheDefpom]

This is why I enjoy buying old broken test gear and fixing it for my channel, HP made excellent equipment with great serviceability.

[@basshead.]

And now they only make crap.

[@ElmerFuddGun]

... and 50 lbs.!

[@gnuheidix]

Is the one "accessible" card edge socket usable for debugging one of the cards by providing better physical access to all components?

[@sbalogh53]

0:06 Your dumpster is a veritable treasure trove. 5:10 Those boards are a work of art, so beautiful. I really love the old HP equipment. They were all so beautifully engineered.

[@X-OR_]

The Board Tabs are arranged in the Classic Resistor Code Colors: Black Brown Red Orange . Yellow . Green . Blue . Violet . Gray White.

[@somaliskinnypirate]

Bad boys rape our young girls but Violet gives willingly ... man, I'm old

[@TechBench]

Better Be Right Or Your Great Big Venture Goes West

[@HansDelbruck53]

@@somaliskinnypirate Not Old. Classic!

[@DehimVerveen]

Dutch: Zij bracht rozen op Gerrits graf bij vies grijs weer. (She brought roses to Gerrit's grave in dirty gray weather) Zwart, bruin, rood, oranje, geel, groen, blauw, violet, grijs, wit

[@X-OR_]

@@HansDelbruck53 Your Right Classic!

[@DanafoxyVixen]

Dont forget to remove that memory backup battery.. its starting to corrode the traces

[@IljaSara]

Came here to say this.

[@TzOk]

...i wanted to say the same, it is pretty green already, you have to act quick. And no one spotted the ERR 7 on the display.

[@PauloSantos-cv1bi]

Those TI chips with the Portugal mark were made at TISEP (Texas Instruments Samsung electronica Portugal) which closed in 1998. The company was housed in a six building complex, covering over 15,000 square meters, and were located In Porto, around 20min from my home. It was the only semiconductor company in the country and the only assembly and test site for ICs in Europe for both TI and Samsung. For those interested follow: www.criticalmanufacturing.com/en/company/headquarters-location-s-history

[@mlkbob]

This is likely to have been made in South Queensferry outside Edinburgh in Scotland. My Dad was a test engineer that worked on these and I was taken in when he was doing overtime on occasion to see him at work. These were made to order and went through a extensive testing and calibration process including being placed in a oven for a day to operate at it is maximum operating temperature before being sent out. This seemed particularly good at highlighting parts that didn't meet specs and it these would be hand replaced. So the rework shown might of been done at the factory as part of the testing and calibration process.

[@benbaselet2026]

Geez, someone got to pay top dollar for their kit.

[@MitzaMaxwell]

I visited the factory in the early 90's on an engineering student trip from Denmark.

[@poncijus]

I work with a lot of guys from there. We actually still make Jitter generators/measurement kit ^^, it's not longer HP/Agilent tho

[@noakeswalker]

Great to see this teardown. Bubble led displays as late as 1984 ?? :o) Almost certainly this was made at HP's Queensferry Telecom Division, which was near Edinburgh, Scotland. That site began in about 1966, and made telecom stuff, scopes, much of that lovely test gear, and medical equipment too. Became an Agilent site after the HP/Agilent split (1999). Site closed in 2010. Dave (ex HP UK ) (BTW Dave: HP in the UK was also at Bristol since 1984 - we made dig data tape drives right through 90s and 2000s. Also there was an HP Labs research building of some note on the site. Tape drives are still made there, but not for much longer, and Labs have vacated the site 2 years ago - that's the end of an HP era)

[@johnfrancisdoe1563]

noakeswalker Where did tape drive production move?

[@noakeswalker]

@@johnfrancisdoe1563 Current HP tape drives are made in Hungary I believe, but designed in the UK and Austria. I don't believe there will be any HP production tape drives designed in the UK after this product finishes - the Bristol site is certainly winding down fast now...not sure what plans HP has for tape drive manufacture in the future in other countries of course. Back in the 2000s, who would have thought tape would still be in use in 2019 ? :o)

[@pocoapoco2]

Also notice the color coding bands on the coax indicating the color of the local board and the remote board.

[@jcc4tube]

I don't want to brag, but I recently designed a board with spare fuse holders plus a LED so the spare fuse holders are also fuse testers :-)

[@benbaselet2026]

Now YOU get a cookie!

[@johnfrancisdoe1563]

jcc4tube Make sure no fault condition can blow the spares.

[@stevenleibson2188]

That jitter tester was very likely made in HP's South Queensferry (Scotland) division, which focused on telecom test gear in the 1970s. My new bride and I (both HP Engineers) visited there on our honeymoon in 1979. They were very hospitable, despite our just dropping in. Those were the days.

[@stiff629]

6:29 The edge connectors at the top of the riser board is a board to make the other cards stick out of the top not for a test/diagnostic card.

[@berni8k]

That does look like a servicing slot extender board to allow you to put between a board and the backplane so that it sticks out of the cage while still being plugged in. Lets you probe around the card while the instrument is running, massive help for servicing. Lovely move that they included this. Normally these would be sold separately as accessories. They don't sell them anymore so you have to make them yourself now (or buy them off a guy like i did last time)

[@jonka1]

That is the item that was always thrown away before I buy any peice of test gear. I end up making them.

[@josuelservin2409]

Those spare fuses certainly won mi heart, absolutely beautiful!

[@ZomB1986]

Tektronics 1502 Cable Tester also has spare fuse ports just like these, and the fuses are 360 degrees transparent plastic

[@hoofie2002]

Built by engineers for engineers. Built to a specification, the price wasn't important.

[@pedromms8908]

16:37 Hello from Portugal!!! I'm really sorry that we don't have here any IC's manufacturers anymore :(

[@MrDannyisr]

I used the 3780a back in the day , late 80s early 90s, Measuring BER for the Air Force communications systems. Very useful to find bad card that was introducing noise.

[@joehubler4965]

I thought I was the only guy with that beast on my bench! got it on eBay for $10. the seller stated, " I don't know what it is, I don't know what it does, I don't know to test, so sold as is." it works great!

[@dentakuweb]

I saw some 54 series in there too. Chris Svec talks about "empathy driven development" in software. This is like empathy driven hardware development where it was built in a way that makes it much nicer to service.

[@VintageTechFan]

There was a glorious time in the 70s/80s were this kind of stuff was MADE to be serviced by the user. They knew the user will be a competent engineer who would see it (rightly so!) as an personal insult if they dare to tell him he isn't competent enough to fix his test equipment. Every service manual had a chapter "Theory of operation" where they explained to you how this device works. I once heard a story of an (nuclear) research institution who was using Tektronix scopes and it happened that they got contaminated, so they discarded them and bought new ones. One day they contacted them and like .. "We are really happy that you like our products, but you seem to go through them quite quickly. Do you have any problems with them?" "No no. They are absolutely fine, but it happens that we have to discard and replace them because of contamination." "Are you crazy? You don't need to do that! We have specialized cleaning agents for this!"

[@02840321]

I used one of these in the old GEC Telecommunication Labs. My job was to design a much cheaper alternative for field technicians, albeit with less functionality. Rms jitter measurement was done by illuminating a small light bulb and photo detector!!

[@Th3Su8]

Noticed how the color coding of the board latches are the same as used for resistor color coding.

[@commodork]

So did I. Probably make servicing infinitely easier.

[@cts006]

maybe "Slightly more intuitive for an electrical engineer or repair technician." I've also seen many wire looms or ribbon cables that will use the same color code for pin numbering.

[@mindslain6752]

8:37 that battery doesn't look healthy. There's already some corrosion on the board and on legs of that SN74LS245 next to it.

[@kilrahvp]

Yeah, was almost shouting "take that damn thing out NOW!!" at the screen...

[@alpcns]

Love this stuff. Professional through and through, built to last. Gorgeous!

[@Jedda73]

Some love went into that design and construction, absolutely beautiful.

[@jagardina]

My first tech job I used one of these at Bellcore to test jitter response of an NEC almost gigabit fiber optic long haul transmission system. This was back in the 80s when fiber was hot and heavy for interoffice links. We were developing standards to assure networks were compatible, without being restrictive on innovation. So I had to build a test to see if a network component as critical as a gig link could tolerate a shift in clock frequency, something that would be encountered in a somewhat dynamic network of multiplexing multiple asynchronous digital channels, the highest standard at the time (1980s) was DS3 or 45 point something bits per second. And it wasn't a synchronous signal, it was never meant to be multiplexed with other DS3 signals. So I drove the Ext modulation with a triangle wave into a DS3 Bit pattern generator, passed it through the Jitter gen, then monitored the bit error rate with another HP bit of gear, the same as the generator, an HP Bet Error Receiver or something like that. This was all hooked up by HP-IB/GP-IB and the result was captured by the HP lab computer, a 9000 series desktop/workstation, highly optimized for lab work, and sent to a pen plotter. As I think about it, I may have also used a Tektronix scope to trigger the whole thing off the pattern gen that created the triangle wave since it didn't have a GP-IB interface. The scope could capture data when triggered.

[@EEVblog]

Thanks for sharing

[@KarlHamilton]

That's so cool

[@DarkFire515]

Nice setup! The combined cost of all that test gear must have been astronomical.

[@flomojo2u]

Bubble displays are awesome, such a unique look! When I was a kid in the 70s I had a digital watch with a bubble display, where you had to press a button to illuminate the display, so cool until I lost it :(

[@gglovato]

man this would make such a cool Signal Path review with experiments to test this in function

[@TeslaTales59]

Excellent HP test equipment!

[@todesgeber]

...bodge wires? well done HP Engineers, good show.

[@dtewksbury]

Very nice of HP to supply the test extender card inside the chassis! We used to have a cupboard full of extender cards to use for repair diagnostics (Ampex gear).

[@ibnewton8951]

I used to write test routines for HP T1 and E1 Jitter Analysis via GPIB on these platforms . Old happy days.

[@petersmith4516]

Love the resistor colour coded boards!

[@nameless5413]

i just LOVE that way of making electronics, that is how you make stuff - orderly, easy to service, easy to understand. modern day electronics with its fancy pansy small size completely lost track of proper design. I was always told that electronics needs to have very orderly innards so as to make it easy to understand what is where and for what reason (i was taught this in early 2000s tho) - simplify maintenance, simplify diagnostic all by just making things adhere to basic logical order.

[@Direkin]

It's all about shaving cents off the dollar now, isn't it? Reduce the board realestate, reduce part count (which is also a good thing), reduce chassis size. Reduce serviceability, increase disposability.

[@nameless5413]

@@Direkin heartbreaking, i do adore these magnificent layouts of years gone by. People whom made these were far superior than i will ever be at drafting layout, most likely thanks to ingrained proper design hygiene with strong pillar of it being testing, comprehensive layout and CLEAN appearance. Oh well i am off to satisfy my nostalgia now you have yourself a good one.

[@SublimatedIce]

Beautiful!

[@WacKEDmaN]

amazing attention to detail...above and beyond!.. just a pity they dont make em like that anymore :(

[@richard7crowley]

Absolutely brilliant. HP stuff was a work of art. Inside and outside. I had a whole laboratory full of HP gear for microprocessor development on-wafer "E-test". The control bus was "HPIB" (Hewlett Packard Interface Bus" before it became a generic IEEE-488 standard and was renamed "GPIB" (General Purpose Interface Bus")

[@thorpejsf]

OMG, old school HP kit is the best.

[@timg375]

Rare to see such beautifully designed boards =D

[@custodiogomesbarcellos4972]

Great video!

[@RemcoStoutjesdijk]

Glorious in 4K. Drove to the office because I have a screen there to watch it

[@MitzaMaxwell]

I visited a HP factory outside Edinburgh in Scotland in the early 90's on an engineering student trip from Denmark.

[@NebukadV]

The gold plating on the pads looks brandnew - really impressive!

[@jockinafrock]

Still got one of these beasts on the shelf in the office. Don't know when it was last used, probably 20 years ago. Conicidentally, I spent all day Thursday faulty finding a 2Mbps clock signal at one of our network sites, comparing the frequency and waveform to standards.

[@rbmwiv]

Work of art. Engineering excellence.

[@userPrehistoricman]

When I'm old and uncalibrated, I wouldn't mind a half-turn screw from time to time.

[@userPrehistoricman]

I think I saw him on the way to the shops about a week ago! He's in Edinburgh doing the military Tattoo thing.

[@chefbink61]

When it powered on and I saw the display I geeked out!!!

[@georgegherghinescu]

More gear like this please Dave! Good one!

[@DougKutyna]

That's such a nice looking piece of hardware. Back when things were made to last forever.

[@FindLiberty]

a thing of beauty

[@intesral]

great engineering

[@MedSou]

*Beautiful* 👍👍👍👍👍

[@ErikTheVikingMechanic]

Buy a service manual. I want to see you repair it and calibrate it :)

[@mUbase]

Bubble 7seg displays bringing a tear to your eye Dave? ahhh...:)

[@midiplaybox3453]

Like for HPs marvelous, engineering, artistic tech!

[@petesmith13]

had to go to your channel page to find this video, only did so after seeing your other video.

[@MWaclawek]

I'm so jealous! In Warsaw there are no dumpsters like the one you showed us, Dave 😍😄 Love these HP equipment!

[@proluxelectronics7419]

The end board is a board extender for testing to component level with the card plugged through it..

[@willyeverlearn7052]

Strolling down memory lane.

[@kullatnunu2087]

Think your knife scares YT. Love this HP vintage. Still have some myself.

[@OC35]

Looks like the card at the end is an extender card for servicing!

[@chrisg6597]

Totally agree with you.

[@richard7crowley]

Yes, it looked like a service extender card So that you could raise any of the cards up for full access while operating. Looked like only power and control signals on the "back plane" so no problem extending a board during operation.

[@berni8k]

Yep it does. I love that they just included that inside. Normally HP would sell these separately as accessories.

[@paulstubbs7678]

I am amazed he didn't show it in action

[@berni8k]

@@paulstubbs7678 Maybe Dave didn't have any test gear repair that needed such a slot extender card so he didn't recognize it.

[@MatthewSuffidy]

15:58 That falls out during shipping and TOTALS the whole unit on power up.

[@kalhana1]

I like that the crystals are wearing jeans :D

[@PaulSteMarie]

Really old school displays had a little column of neon lights for each digit. Each column had 10 lights, about 5mm diameter, each one with a digit from 0 to 9, and one light in each column would illuminate to display your number. The multichannel analyzers in the undergraduate physics labs when I was in college had either that type of display or a paper tape print out. Either way, doing the data analysis was a ripe royal PITA.

[@zaprodk]

The socket in the back is not for testing at the factory. It's a complete card-edge extender that you can pull up and use with any of the cards so you can debug them while having full access to the card. I'm surprised you didn't know this :D

[@rustyrebar9647]

Those 'large carbon resistors' are actually rf chokes! These fuses are also rated for rf performance up to 500 MHz!

[@radarmusen]

Like those display, has worked with the pattern generator there could send hdb3 code. Guessing it was a more new version due to it was fiber communication.

[@k7iq]

I miss the old HP buttons with the light in them

[@TheDefpom]

@20:20 I am pretty sure that you would just remove the entire front panel to access the back of the front PCB's.

[@pdrg]

Lovely bit of engineering

[@freeman2399]

Looks like a seizure generator with all those blinking lights :P

[@muzzaball]

Excellent tear down Dave, good job as usual. I thought the manual etc was in the brown /black folder on top of the unit?

[@ovalwingnut]

A highly valued magically mystery tour of this H.P. (Hugely Popular) device. Thank You 🤓 Feel free to take the weekend off....

[@EEVblog]

I will sir!

[@herculanovalada2910]

hello from Portugal :-D

[@soothcoder]

So is the extra connector on a riser board or did you have to move the board into that slot to us it? I repaired a R&S sweep generator that conveniently came with riser boards but then the coax connectors were all at the bottom and the coax was too short to connect to the board when it was on the riser (doh!!) I ended up buying these cheap SMB (and some SMC as they can't make it too easy!) patch cables so I could debug the boards while on the risers. At least HP made the coax long enough so the board can be debugged!

[@andersvandegevel8355]

That dead battery is probably the source of that ERR 7 code. I just got a HP 3784 Digital Transmission Analyser off a lowball ebay bid and it shows an NVM error, likely the same problem. Now, if only I had a use for the thing once I fix it...

[@spagamoto]

Backplane extender card for debugging and spare fuses *included* in the unit. Everything color coded. Easy test points. Disassembly instructions printed on the unit. This is what you get when you let people *care* about their work. Could you imagine your shiny Apple product even coming with a lowly baggie of spare screws these days? Nah glue her together she'll be right.

[@MrMcsoftware]

Always nice to see Harris parts since I used to work for Harris. I even worked for a Harris division across the street from Harris Semiconductor. Harris sold the semiconductor division and that became Intersil which now is some other company (and the building is no longer semiconductor manufacturing - the building is now home of Larsen Motorsports (jet dragsters)). I wonder if I could have gotten a special tour of Harris Semiconductor at the time (and I even knew some of the employees there). Oh well, too late now.

[@mischiefmonk]

Grew up in Palm Bay, Dad worked Harris. I got a job at Acent Media, owned by Harris Corp. Worked for a company that did A/V stuff for their corporate office. Now I work with old Harris Microwave Radios.

[@MrMcsoftware]

Small world I guess (at least 2 viewers of an Australian channel who are associated with Harris). BTW, it's now L3Harris, and the nice Harris "H" logo is a thing of the past. :-(

[@MrMcsoftware]

@Ed Chambers This previous message might not have been directed to you by youtube, so I'll repost... Small world I guess (at least 2 viewers of an Australian channel who are associated with Harris). BTW, it's now L3Harris, and the nice Harris "H" logo is a thing of the past. :-(

[@sicnemelpor]

missing the gorgeous displays teardown...

[@anthonysibley1021]

I collect telecommunications test gear....I would LOVE it in my collection :( That card on the end is an extender card, so you can have a card connected but out the top for repair and servicing

[@JerryEricsson]

The breaks of living in a small town hundreds of miles from any city. No dumpsters with any great stuff. Hell we don't have dumpsters in our town, just plastic dump cans. Ah well, last shooting here was ten years ago, in my lifetime of 68 years there have been 3 murders in town. Great safe place to live. Guess I can get by without dumpsters.

[@williamsquires3070]

The electrons come to a screeching halt going through the bend in the ribbon cable! 🤣

[@johnfrancisdoe1563]

William Squires Or maybe the 45° bend causes the reflections to get around the corner. Not an RF engineer so I wouldn't know. Anyway the HP-IB bus wasn't a high speed bus, just an extremely convenient one before USB.

[@sanjev21]

I can easily tell how rich a country is just by looking at the dustbin as shown in video.

[@pango6705]

5:55 So, basically Software has gone from Monolithic to Microservices while Hardware has gone from Microservices like in this to Monolithic stuff where everything is integrated.

[@Rob2]

06:30 no, that is an extender card that you can put in any slot and then plug its card in it.

[@TheStefan665]

i was screaming at the screen when you bent that pin :))

[@gavincurtis]

Different guys make their modern printers obviously....

[@benbaselet2026]

Same letters, nothing else is the same.

[@shovon134]

Yeah I've enjoyed it. But you should show us the front 2 boards.

[@funkyironman69]

19:48 I think those Kemets are tantalum as well

[@mikemike7001]

Beautiful stuff. Gorgeous buttons and spring-loaded heat sinks. But all those flickering LEDs on power up self test made me feel a little, er, jittery.

[@schnibbelwind91]

Didn't understand why they not using these nice buttons anymore. Would love to feel tactile buttons in new test equipment again.

[@berni8k]

Im guessing its price. Tho these leaf spring buttons do get wonky with age. The springs get out of shape for some reason, but you can open it up and just bend them back to make them work like new again.

[@ianwilliamtait9909]

At first glance, all the trimmer pots are facing towards the top for fine tuning In Situ (Latin phrase that translates literally to "on site" or "in position." It can mean "locally", "on site", "on the premises", or "in place").That hold down brace looks like industrial formica or an industrial laminate

[@jamesmdeluca]

Greetings: I hate to burst your bubble about the center LED llit switches, but I had to constantly replace these switches on equipment used for production rather than testing (reel to reel video recorders). The operators would poke rather than press the switches imparting a significant stress on the switches that have a very small section of plastic used to contain the return switch pressure after releasing the "poke". Yeah, I also do find them attractive, but had to ofset that with the worry "how soon would I be replacing it again?".

[@sashenko]

Calice de tabarnak that's some quality gear

[@joopterwijn]

Just wondering what you do with equipment like this HP after your tear down (eevblog behind the scenes 🤔)

[@KeanM]

Sometimes they go up on ebay (I've got at least one item from him), otherwise it would hopefully end up back in the bunker

[@GeorgeWMays]

Ah, once again. this seems to have been designed when ships were wood and men were iron....

[@donvito1973]

I love how there is no silkscreen.. All the component designators are in the copper layer

[@jamesmdeluca]

Greetings: It turns out that jitter was the reason that SONY developed parallel to serial converters for digital video as it was easier to deal with serialized faster speed video than slower parallel video when using multi-conductor cables. The small differences in individual conductors had bits being received unreliably when jitter was factored in . BTW: those SONY chips would ALL fail; not if, but when.

[@samfedorka5629]

Those Teledyne relays are extremely expensive. I counted 9 on the grey board, one on violet, 6 on the green board. 4 more on red. 3 on brown. That's like $800 in relays. I wonder if the missing link (LK2) in the middle of the red board is a cause for concern.

[@MrTripcore]

When there's a bug, it's a jitter bug.

[@neteagle2k9]

No news from the custom LCD µsupply ?

[@glenslick2774]

They saw into the future and added the Agilent logo next to the External / Internal Clock push button.

[@donpalmera]

I like the way the traces are routed like the board was done by a youtube JLCPCB shill making their first PCB. I'm sure HP know better than I do but traces at odd angles going point to point give me shivers.