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- Опубликовано: 8 сен 2024
- Dave does some performance checks and then tears down a Krohn Hite EDC 4601 0.05% 6 decade 1ppm resolution 0-1000V AC voltage standard.
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My guess is that they made (make?) so few of these that there's one chap in the factory who makes them. He's probably a grey-bearded, pipe-smoking eccentric genius who's been employed by EDC for the past 45 years but who they don't dare question or god forbid allow to retire because he's the only one with the green fingers who can hand-make these to 2 x better than the stated precision...
When you showed the oscillator board, it was like Wizard of Oz going to color. Can't believe that's in the same product as that tin-plated fiasco of a main board.
dwDragon88 Good analogy!
Well, this just goes to show, if you know what you're doing, you can get anything to work. Whoever put this together (ok it was probably a team of people) really knew how these worked. To be able to recycle old parts and designs by strapping on new technology where needed, that takes skill.
Darren Jacobson For sure. Getting a reference like this to perform to these sorts of specs is not trivial.
I still use vactrols in some of the stuff I build. They are very useful for gain control in analog circuits because they are super linear and also provide isolation.
"The light weight of the unit makes it a desirable laboratory instrument".... hahaha it weighs 40 pounds and its got NE 555 timer at 24:45
they are planar mosftes I believe. Top quality.
Something to watch out for when using the higher output voltages is the screw-heads on the sides of those 4mm banana plugs. The exposed screw-heads are live! There's a big hazard here if you grab the plug when the voltage is turned on. Those 4mm plugs are best avoided in test gear -- even at low voltages, they run the risk of causing a short-circuit.
Jeez...I stumbled in here to find Dave blowing a voltage standard...now THAT is true electronics porn
Errr... Blowing... Hehehe
I would really like a walkthrough of how this AC Voltage Reference works, perhaps with some state-of-the-art Dave CAD drawings :)
P.S. those Vactrols are frequently used in analog synthesizers for various voltage control of diffrent parameters and they are stil manufactured :)
Back in the 1960s, my brother, a Ham Radio operator had some surplus aircraft radios that he converted for the ham bands. He powered them with a 24VDC dynamotor. The radio supply output was 400 CPS (Hz). They used 400 Hz so it didn't take so much iron in the transformers. Lower frequency meant more weight which resulted in fewer bombs... :-))
All these videos with insides of various instruments are very riveting.
Dave, wonderful nostalgia seeing all the traditional analogue electronics! Very good photography. Keep up the good work.
I have never quite understood the "don't turn it on" part. Why not? Seeing the device in action, seeing what it actually does, is very interesting. Why would you deliberately skip that part (unless the device is broken, of course)? It makes no sense.
Sure, it sounds catchy, but it makes no sense.
You make no sense.
It makes sense with something like an E-book reader or a Playstation, but with things like this voltage standard, He almost always makes a quick review and measures its accuracy and stuff like that.
If you ever turned on a piece of equipment or other electronics only to see it die in front of you and you would understand the saying.....checking inside before application of power is very wise.
It's just an AC voltage standard. What do you suppose it does? Spits out a very precise sine wave. You have a couple of knobs for voltage, current and frequency and that's it. It's not like it has Angry Birds installed on it.
TechnocraticBushman the parts might explode becaus of old age
I've seen a few audio amplifiers use a 'vactrol' type arrangement for soft-clipping circuits. It is always just an ordinary 5mm LED and an LDR in a piece of heatshrink with some hot melt glue.
That resistive opto-isolator says that is assembled in RP...RP is the Republic of the Philippines.
I knew something was off with that conversion... 18.14kg is 40 lbs not 50. Probably a typo as it's extremely close to 40 lbs.
I'm a bit late to the party, but I have been wondering about that too. It just didn't seem right.
Edit: typo
That's a great old hand-built unit. Love it!
The traces on the board (especially the top) looks to me hand laided out and the parts hand placed. Reminds me of my first bare copper board back in the 70's. Ahhhh, the smell of warm etching solution in Mom's (Mum's) nice Pyrex dish!
In the audio business, we use Vactrols/Opto Couplers a lot. I currently make my own which consists of a CDS cell and an LED facing each other then isolated. I use Black heat shrink tubing. FYI, Yellow LEDs give the best results and choice of CDS will be to your needs.
Notice the back to the future 2015 transformer
Note the date codes of the trimmers on the mainboard. They are also 99xx and the trimmers seem to be original. The mainboard seems to be hand drawn/routed while the card does look as it has been designed with some modern evil CAD program :)
Chip Guy Vids Didn't notice that at the time. Almost certainly dates this to 1999/2000 at least then, so the cal sticker could be factory original
EEVblog Very probable that the cal sticker is factory original, if this was used in a cal lab then they probably measured it's output with a calibrated DVM that would have provided the tracibility. In the cal lab I used to work in eons ago we would have a lot of different sources such as this AC voltage source that was then measured with a Wavetek/Datron 1081 8.5 digit multimeter. The multimeter would be calibrated every year but the various sources rarely calibrated, usually only after one had been repaired.
Nobody live in a damp climate, no? The residue looks a lot like mildew to me. I've seen many an old circuit board with mildew on it. Doesn't do them any good. Interesting to see it has the 400hz supply on it for aircraft components, not that you could do much with 25 watts on the AC systems of an aircraft. They're seriously power hungry.
I use vactrols all the time in my DIY analogue modular synthesizer. Probably have about 30 in there aleady. VTL5C3 are favoured in most applications for the best timing curve, VTL5C4 are usable but a bit slow. The /2 suffix represents dual versions.
Dave, anyone, please don't judge things so much by the looks. I can tell you from my experience with repairs that devices fail mostly due to (intentional) poor choice of components; that includes lead-free solder. Some of the worst offenders actually look "highly professional." I have several bird's nests of mine I had made 10-20 years ago still going strong, on duty 24/7!
Hellllarious! Blowing Blowing Blowing... "Never tried that before" Blowing Blowing "You never know until you try it, and it makes for good video " Good lord, I bout fell out my chair!
9:30 Now I'm confused. You'd think the manual for a transfer standard would be a bit more precise in its unit conversions. Maybe we can chalk that up as a typo?
Did everybody else notice several of the trimmer pots have mid-99 date codes?
That "soot" almost appears to be remanence of roach droppings.
Looks like mold to me.
I wonder if all the crud on one board came from an earlier failure, where something self-destructed and shot gunk everywhere?
That's what I was thinking. Maybe one of those medium-sized electrolytics in that vicinity blew up?
@ 7:50 try the Fluke 5200A... that’s closer to 30KG, and then you need the high voltage unit to go over 111v, which is even heavier and bigger!
Sad to see that it does not have any wire lacing in it, wouldve expected it in such an old (and expensive) piece of kit...
I've learned a lot tonight. Thank you so much.
I'd expect that with such a low sales potential for test gear like this, they'd design a standard chassis for a series of units with cutouts to suit all the models they plan on putting inside it. The soot by the PSU section would probably be from an exploding failed component at some point in its history. The repair tech would have just cleaned it up to the point it didn't affect anything and left it at that.
The Epson SPG8640AN has a crystal built into the DIP package (presumably one of those watch-quartz sized thingies), that's why there is no separate quartz anywhere near. I've got a few of those chips around.. might even sacrifice one for a micro-teardown ;-)
Starting at 24:38 talking about the Vactec Vactrol part. The data sheet shows four leads, two for the LED and two for the photocell. But this part has five leads. Hmmmmm.
The problem with generators from the Northern Hemisphere though is that the electrons circle in the wrong direction :-P
9:28 but 50lb=22.7kg. weird.
EDC stands for "every day carry". EDC voltage standard is hard core.
14:40 Those also balance the voltage across the caps; very important when you have filter caps in series, what with their crappy ESR.
Rather dodgy taped layout with liquid tin coating, no solder mask, but hey, still within spec after 15 years. I just wish they'd have taken more pride in the layout.
That's an utterly lovely American accent there at 0:19
to my eyes looks like that that crusty stuff in the power supply area is from a couple of blown caps as the filter caps look new, just a thought
Ok for the last time: BOB is NOT my uncle!!! its Steve! Steve is my uncle! geeez.
I would have liked to see how clean that output is but i dont exactly think an 8 bit scope could really show it!
"Never trust an instrument that doesn't hum". Love it
I have to say, that thing looks like it was built in the '70s, the design of it, the looks, the layout, the way it's all bodged together inside, very 1970s, and yet, it's a lot more recent than that, scary... :S
Still, it's not made in china so will last for many years to come... :D
2015, right there on the transformer:)
Love the Boston accent.
"...very sort of (you know) HP 200 oldschool used in a light bulb as the main stability element in your oscillator" - what exacly do you mean? I'm very interested in this kind of sollutions. Please more info about this. Thanks.
Very nice video BTW I like "rare" gear tearing down.
*blowing into scope*
"Ahh this makes for good video"
hahaha!
+naota3k
He blew in the device under test, and the device you saw was a multimeter, not a scope.
FUCK
*deletes the internet and kills self*
It sounds like the engineers were told to use all the old stock....
The right instrument for calibrating this would be a Fluke 5790 AC Measurement standard
Would have been nice to examine the output waveforms...
Can you measure killaherz with a moldymeter?
The crap and grease on the board looks what it would look like, if one (or maybe both) of the Caps were blown recently.
That board looks older than what's in my Commodore disk drive.
Could not understand the need for the giant transformers if all this can provide is 25 watts, even if the efficiency is 10%?
Black dust looks like typical CRT dust gathered by electrostatic field.
(Google comment system doesn't let edit -.- )
I was also surprised how it looks from inside for it's accuracy, good thing is that all the IC are socketed, makes the repair much easier.
Ron Jeremy of electronics.
Is "beesdick" an SI unit?
looks like it had an internal fire/explosion and was repaired
How come the average on the Agilent is showing 1000+ volts while the real-time reading never exceeds 999 VAC for the whole video??!!
Holes in the chassis...you know it didn't get down to 18 kilos on a low carb diet! Weight savings!
Why are the transformers even that large? I guess you might as well put em in there but dang
Wish thay wold do throhole these days
Sorry, I meant 1.000VAC and 0.999 VAC.
There's an external input.. Could you use it as a mono amplifier ? :P
Specs say external input is only from 50hz to 1khz. Would be really low-fi
Uhm, ya, that's true, I didn't think about that.. :P
I get the distinct impression three teams of engineers worked on this device and never spoke to each other except through an agreed interface. It looks like a very FRANKENSTEIN type of engineering. I was groaning through most of the video. It could be the company knew very well they weren't going to sell many and did not want to put much effort into the "back end".
It can be clearly seen that they put effort in this thing, otherwise it won't be that precise. It is not that clean, it is built by older looking style, looks somewhat DIY, but clearly working very well. It needs many iterations of a design to converge to the perfect, but you have to redesign many things over and over to finally look like it is the first perfect cleanest iteration. But this is a low volume thing, it is probably not worth to make it any nicer than this, it would just add to the internal aestetics, not to the specs.
Could those drilling holes on the chasi be there for a valve rectifier? Is this design that old?
18.14 kilograms = 39.9918544 pounds
50fps video. It looks much more fluent. Much better. :)
When you say America you need to say it like AMURICA like us country folk !!!!LOL
"3/4 of a bee's dick of the range." LOL
Is that a 1988 datecode (8810) on that one trimpot on the far right?
There was other pots with 99 datecodes as well. Looks like they just used what they had lying in their part bins for the last couple decades. I guess when you only build so many, you buy things once every few years in bulk.
David Richmond
Not every American sounds like John Wayne
where can i get precision resistors like this?(on switches)
"nnnnneeee pissing in the wind"
1/2 a bees dick of the range! love it! :)
Can Dave use this thing to power and test US voltage devices??
MatthewSuffidy I already have a programmable mains AC power supply.
In the United States of Amerrrica!!
It doesn't look designed any more. It looks like it evolved. 0,o
um ah um ah you probably know what um ah you are um ah talking um ah about but um ah looks like um ah a lot of um ah thought goes into it um ah
At least I'm second
I guess you only get 1/2 of a browny cookie.
First comment!
Stop pronouncing it "Amerika" lol