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: https://www.eevblog.com/forum/blog/eevblog-1237-old-school-teardown-hp3785a-jitter-analyser/
#Teardown #Vintage #HP
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Teardown of the HP 3785A Jitter Generator & Receiver with beautiful HP bubble LED displays.
Forum: https://www.eevblog.com/forum/blog/eevblog-1237-old-school-teardown-hp3785a-jitter-analyser/
#Teardown #Vintage #HP
Bitcoin Donations: 38y7DE8HEHNj8fGDtUr4PkCn9nWxiorvvy
Litecoin: ML7oQokTwB38bgzzjLDbRV97HKAHuwRfHA
Ethereum: 0x11AceA38DCA9DbFfB4F35f3F746af65F9dED28ce
EEVblog Main Web Site: http://www.eevblog.com
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Support the EEVblog through Patreon!
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Hi it's random teardown time from an item from my bunker. this one I got at the dumpster dive are quite a few months back. I've done a video on that - I'll link it in down below and at the end if you haven't seen it anyway, look at this gorgeous bit a kid. Hewlett Packard none of this agilent or Keysight rubbish.
37 85 A jitter generator and receiver? Isn't it a thing of beauty? Look of the old school HP buttons on it. Ah and I'm sorry I've got to turn it on before I Take it apart because I've got to show you the displays on it. Let's go Oh big fan were Oh I can see it's little LEDs flickering. can't see those in real life.
that's the shutter speed the camera. but we've got bubble LED displays. Oh love them. So this is quite a specialised bit of Industry Kid, it's not something that you'd find in a general lab.
What is a jitter generator and receiver? Well, you all know about signal jitter. where you see you know, can go, just have a little bit of did he need a wiggle-wiggle-wiggle year on it and it jitters back and forth and that can cause data errors on on serial transmission systems among a whole heap of issues. Well, this particular jitter generator and receiver is designed to simulate and measure jitter as well and basically our performance analyzer telecommunication or phone line based systems hence 120 ohm balanced lines here and stuff like that is designed for to meet the Ccitt standards of the old Ccitt telecommunication standards right up to our Ds3 or so you might know. that is like our T3 which I think this will go up to like 36 megabits per second so you know it's It's not vastly fast, it's designed for like old still school telecommunications systems, but it's designed to like, you know, certify those, qualify them, test them, troubleshoot them, installations and designs of various telecommunication products, and I just love the old school buttons on these.
They got the classic click on it. Ah beautiful. So anyway I pretend to know anything about like testing telecommunications systems and phone standards and all that sort of jazz. Anyway, this bit of kit is designed to measure and talk to that.
it's got HP ib. Of course we could control it with our the our new Ethernet GPIB controller. but anyway I just love the bubble displays. They're gorgeous.
If you haven't seen those up close, they're actually like they are little LED displays in there little LED segments and they've got little like a lens bubbles on them that make them appear bigger than what they actually are and these were very popular. You've seen them in our various calculator vintage calculator, tear downs I've done over the years and stuff like that made. they're just fantastic. Oh, you can see my macro lens anyway.
this does appear to work so you know we're getting all the requisite displays or looks good as responding to the key presses when you actually pair it up, it goes through a pair on self test and yeah, that's so I presume like do not use until tested and calibrated last calibrated in 96. So let's tear down this beautiful bit of kit and see what's what. I Don't think we'll find much surface mount rubbish in here. There's the back for those playing along at home. It's got a proper look. You've got to pull these out those latched switches so you can't accidentally like drag cables around the back and and bump them so that's a nice attention to detail. I Like that. Wow It's made in the old dark.
my British viewers, This is fantastic I didn't know hates pre-made stuff in Britain Um, if anyone's got the history of that I assume it's a HP product. It's not like some other one. Repress: It's got the H or the HP look and feel. So yeah, let us know the history of that.
And for those who just like to see it in all its glory, oh, this is looking like it could be easy. It looks like it's split into two halves, of course, top and bottom. It looks like we just do a half-turn screw on here and that might just lift off. That'd be great, all right.
So I Expect this to be your jam packed full of ballers and probably are quite difficult to get them out, but let's have a come off. Yep, no extra screws under there and they work half turn. By the way, Oh no, isn't that nice? Look at that rock. They said we can just take that out.
We get out all the individual boards. Oh I Thought it'd be like much larger ones, but that's beautiful. It's even got thoughtfully provided tear down instructions to remove the power supply. Take out these screws marked with the black rings.
Awesome! You can immediately see the benefits of the old-school design here, not only from a service in an aspect point of view. you just take off. These are panels here and each board has that levers. you can just lift out like that and the boards come out.
You can replace them, you can work on them, but we've got the test point all along the top here, so that's just. it's absolutely brilliant. So fantastic from a servicing point of view, but from a design point of view as well. They divide up all the functions onto separate boards and they'd each have their own separate schematic that each have their own separate revision.
So if you wanted to, you know, modify the clock board, you had to revise that you're only revising the one board. You can segregate the design. You can give them two different design engineers. Even the boards can even go the different board layout engineers and you can like they're just compartmentalize the design of this sort of thing when space really isn't a problem like back then.
The size of the instrument didn't hugely matter a lot. Yeah, maybe you know either back then I'm sure it probably could have used some surface mount technology, some sort of you know, more advanced stuff back then and made it more compact, but you know you just didn't need to. So dividing your design up like this just has awesome benefits. So yeah, I'm throwing two, four, six, eight, ten different boards. Interestingly, you look up here as another card edge connector up there, so that seems to go right down to the bottom. So maybe that's a test card ax you can put in some sort of production test card. That wouldn't surprise me. they would have built that into the design of this thing.
Maybe it's a like a troubleshooting and repair card or something like that. You can put this in urk and run. Diagnostics is probably access the main bus which had no doubt be on the bottom of the board. would have to start taking out the boards to have a look at that.
But yeah, and of course there's no getting away running a ribbon cable. They've done the right angle thing that's going over there. that would be for your GPIB So it's just easier to run the ribbon than it is to try and design the right angle connector and then get it out the back. That would be a pain in the butt.
So ribbon all the way with LBJ And then got a separate board on the front here that's obviously like front panel. probably just front panel control. I Don't think that'd be a main process in or anything like that. probably just a small auxilary processor here for you know, doing the front panel, all the switches or the lids and got some encoders and things like that.
So I think probably a although like how much processing is there in this thing color-coded levers. so I'm sure the service manual for this thing would have been like pull out the yellow card. you know I am fantastic. Tension to detail.
they don't do this anymore. This is brilliant. That's why I Love these vintage. Tear downs is great.
Metal threaded inserts into wood. Is it for the divider for the board? Anyway, that is gorgeous and this is the board from the far side of the unit which I'll call it next to that riser board. We have a date code 37 for week 85 for the firmware here, so obviously this is some sort of processor board. we'll take a closer look.
Love the gold cap ceramic packages here. Fantastic and this went over. This is the ribbon cable that goes up to the GPIB up there, so one of those would be the GPIB controller. No doubt.
Check out the rechargeable battery made in the United States of America USA USA USA that is crystal socket porn. Look at that. Oh, now of course the problem with H Peggy is that it all uses HP part numbers for everything. So this 1820 to 293 date code 42nd week 83 for those playing along home Motorola Job HP famously ordered most of their parts with HP part numbers on them so it could be a standard you know, Z80 processor.
You know it could be in like a standard anything. but HP would order such volume and they their internal systems demanded that they have part numbers for everything. Of course you know we've got some standard 74 series logic and stuff like that. But yeah, HP part numbers for there it is again. so you can actually look these up. There are databases of HP part numbers and cross-references and stuff like that so you know I won't go to town here. One thing you don't see anymore is look at these tags. These are serial number and revision tags soldered onto the board.
That's brilliant. And of course you get a bunch of test points right up the top of the board. No point having them down the bottom because you want to troubleshoot this thing while it's in the show. Z and in reset button Fantastic! 45-degree PCB traces.
Highly overrated and it's very interesting to note that there's no cutouts here in the card edge sockets they don't like extend down to the bottom of the board. That means if you have a look down on the motherboard as we will eventually, you'll no doubt see that the that. The card edge socket on the board though actually I won't have like an end to stop on it. It'll like just be out and so the connector will probably stop here and here and the board just extends out the edge of the connector.
Me: Now if we lift up the second board here, you can see that we've got three cables on this and one of these cables here is. well, in fact I think But yeah, I think both of them might be. All three of them might be buggering off to other boards here. I think and pretty sure this one goes down to one of the other boards.
So here's where signal integrity starts to matter. They couldn't get there signal from there for down to the bottom of the edge connector, through the motherboard and back up to the other board. so they ran a coax. They're nice.
Oh, you rely aficionados. a wet in your pants Now look at this. Teledyne relays in metal can package. Ah thing of beauty and is that chip? there? Is that a Harris Technology logo? So that really is something.
There's a whole array of relays and some sort of IC I'm not sure why. So the relays? okay and the ICS are you? of course you 36 down there and there's a whole bunch of those on there I Don't know. does this board have a name? Does I have a purpose? I don't know I don't have the service manual for this? Haven't looked it up but don't know? Nope. it's the card with no name but obviously ah, there's two chippies under there little last ceramic jobs.
They get a bit warm ski and they put the thermal paste on there and a nice-looking spring loaded heatsink. No vintage tear downs complete without RCA One really cool feature of these little black things here. these are actually jumper links with little inserts. There you go so you can take them out.
Get in there. you can measure and currents and you can break into circuits and and things like that. Of course it's It's not a layout. Reason they could have just put the tray straight across there.
There's a specific design service in, you know, troubleshooting, debug, measurement, Reason to have that. Or I bet the pin is, they're a real pain to insert back. Let me tell you, and we have had a bit of a hairy hacker here. You can see that you're one of those RCA jobs up there. This one sold it perfectly, but this one over here someone's had a hack at that. You can see the flux residue and like a couple of pins around here you have flux residue. A couple of pins up there, just a few pins around. so this one's definitely been hand touched up.
Maybe someone was troubleshooting and just getting a bit desperate are resold some joints and here's the board that that first coax went to went down into here here. We got some pretty stock standard-looking Omron realize so once again I don't think these don't have a functional what's got masks? whatever that is reference set high Q standard option. maybe their you know option on the product or whatever. Yeah, anyway I don't know.
Look I'm not going to go into design detail and get out the it if he even can get the yeah service manual for this. I'm sure it's out there somewhere if anyone has it if I can't find if I find it I'll link it in if I can't find it and can if somebody has it. please send it so that because people won't love to check out the service manuals and it will no doubt be an absolute thing of beauty and a joy forever. And let me tell you why I guarantee it.
is it the or and we can see the sockets down in there as I said yep, they've got the ends cut out so the boards you don't have to make like you can just make them square boards? Nice. Yeah, get more on a panel and they've even put plastic guide protectors on there for the cable so that the cables don't get caught on any sharp edges on the middle work. Once again, attention to detail is incredible in this thing. More attention to detail you take out this board because this coax have to travel all this way right across.
They decided just to put a little tie in for that. that's absolutely fantastic and looks like we're gonna get some more large socket porn. Look at that that so there's not a huge amount on that. Just a bunch of discrete trainees over here.
We've got some date. they actually yeah, they be. Yeah, they'd be oscillators. really like, you know.
Colpitts a variation type oscillator. Various crystals they'd be are for the different bit rates, but they've devoted an entire board to that pretty much Wow Uh-huh those white things. They're the diffusers on each bored and it actually has a label on the top of this. say in each board.
maybe into individually fused for its own protection. Neat. and there it is. It's got a glass top on it.
Never seen a fuse like that before. but look at this. they put room for a spare. Oh wow.
well done. The design engineers at Hewlett Packard That is ridiculously good. Oh I Know what all is Now it just dawned on me now that all the boards said the same thing. orange. they they knew at the PCB design stage that they were going to put orange levers on there. That is ridiculous Is this? this one has yell for yellow? but it's actually green. Whoops goof. Every spin the board some of that newfangled HC rubbish.
Anyway, we've got more of those ceramic dip packages over there with the heat sinks. bunch of chippies down here, bunch of digital stuff. jeez, are there any Portuguese fabs left anyone? Bueller Bueller When was the last time you saw a Portuguese manufactured ship? Any weights and big ass carbon resistors up there? Tons of metal can packages? Me: Oh, now we're stepping up the coax action. Look at that that goes off to one of the BNC s on the front panel.
More socket porn, more spare fuse porn. It's just his videos demonetized. Maybe I wasn't paying attention, but I don't think I had soft tag dancing here before Tate and I was one of this the the tantalum plague. So anyway, yeah, they are.
They're notorious for catching on fire. The old tag dance yeah, does anyone use them anymore? And this looks like a output driver board because we've got more big coax is going to the B and C's on the front. What? They've got the correct color? They've got it red. Well done.
Anyway, there's another just pin cable. What's that? A little little chair or transformer? perhaps? What's the designator on that? There is none. Mm-hmm Anyway, and they're getting more serious about their tag tents. That's some pretty decent sized ones.
But yeah, I don't know. Some sort of output driver bored me and more. It's gonna do a bit more than that. Yeah, that's not.
now. put driver board. That's an output driver board. Yeah, got a whole bunch of the double ceramic jobbies over here with the two big coax is going off to the front there.
and yet even even the poor little like and packages over here had to get some little flowery heatsink. Something cute. Those little packages. yeah, a little bit hot ski so they are just whack some fins on there once again.
I Think that's probably some sort of transformer. Oh, that could be for the hundred and twenty. Oh Imbalance line. Perhaps that'd make sense.
and there's the base of the unit. It's all pretty much just power. and like some like main signals, not any of the high frequency stuff. As I said, that all goes over the coax plane.
By high frequency I mean you know, tens of Meg's this the power supply board for you Power supply officiator knows we've got a switch mode supply. You can tell up there we've got little heatsink that's all insulated individual devices on there. We could probably have a look at those. whoa, no, no diodes.
look before you. Yep, on. Dave They're obviously diodes. Look at that.
Fantastic. So this, that's how I said a bridge rectifier. Terrific. Anyway, some more custom transformers happening down here and the caps? What brand they'd be genuine? Das Prague Sprog Sprog Fanboys go wild. We've got ITT jeez, there's a few different wins and Nippon chemi-con Of course there's a few different winds on in Kemet and Kemet caps. It's all over the place, but they're all top-notch brands. Of course it's why it's still working after all these years. or there's a hey, a couple of little custom trainees down there look, but they're quite neat.
Wow Really gone to town on that custom supply and please forgive me for not getting out the display controller board. But yeah, there's screws in there which you have to get out the rest of the chassis so that one is not hugely serviceable like the other ones. Unfortunately, you got to get there. You know you got to take out the whole cage and everything.
so did you? Nothing special. We've seen all the good stuff, so there you go I Hope you enjoyed a look at that. Three Seven eight, Five, a jitter generator and receiver teardown. It's absolutely brilliant.
They just don't make them like this anymore. Oh, you know, some companies do. depends. like if you've got the room, big industrial stuff and things like that, you know you still do plug-in cards.
it's quite common. and then you segregate your design into the different blocks and things like that. Then your design team can work on the different parts and you can modify different parts. You can isolate problems by replacing boards at the troubleshooting stage and things like that.
but yeah, like in test gear and stuff like that anymore. Like it's just, it's just not a thing and this thing's just wonderful. Wonder how many of these things they actually sold in the end? If anyone knows like how popular these things were did every single you know, telecoms tech in the business, have one of these back in the day and cart it out in the field and you know, set up measurements, Let us know. I'm sure there's somebody out there who's extensively used one of these.
Good service. One of these puppies in next to no time. Let me tell ya, these quarter-turn screws, it's still going to work. Course it will.
Beautiful. See If we get anything out of well, we have a 2.0 4, 8 Meg clock out. winner winner chicken dinner and then eight. Meg Well, eight point four, four eight.
Meg Actually and option don't know an option is then we don't have the option. 34 Meg 34 point three, six, eight. For those playing along at home, well I'm pretty much embarrassing myself trying to use this thing. you know I just can't get this manual control to adjust the generator jitter and we can like sit through the data.
so if we do that, of course it vanishes through the word. So we put it through the clock and we generate our clock. No problems at all. But then how do we generate our jitter on the clock? I might have to RTFM But yeah, I don't even know. Forgot the manual. Hmm. Anyway, I'm trying I'm doing my best. I'm randomly pushing buttons like a monkey and oh, not much is happening.
Nothing's happening actually. So if you liked that video and if you like just random bunker tear downs, then please give this video a big thumbs up. Share it and all that sort of stuff because you got to share it these days because, well, YouTube doesn't do a very good job of that anyway. as always, comment down below or over in the Eevee blog forum and I'll have high-res teardown photos of this I Always take photos with my Op macro camera, my macro lens and yeah, high res photos over on Eevblog comm which links to my Flickr account.
Catch you next time.
Excellent HP test equipment!
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.
Those 'large carbon resistors' are actually rf chokes!
These fuses are also rated for rf performance up to 500 MHz!
hello from Portugal ๐
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.
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?".
You simply don't find build quality like this any more. That being said I'm sure it had a price to match back in the day.
You are so obnoxiously British that this was painful to start watching, but I soon forgot about it because the video itself is actually really good.
I like that the crystals are wearing jeans ๐
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.
I collect telecommunications test gear….I would LOVE it in my collection ๐ That card on the end is an extender card, so you can have a card connected but out the top for repair and servicing
That's not an output driver board that's a spoon ๐
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
I'm so jealous! In Warsaw there are no dumpsters like the one you showed us, Dave ๐๐ Love these HP equipment!
I visited a HP factory outside Edinburgh in Scotland in the early 90's on an engineering student trip from Denmark.
Large amount of mica-silver capacitors!
Gear made by humans, for humans
Love old HP science equip. Works of art and engineering.