Why Can't Industry Use Schematics?????????

RANT mode: ON!

I have spent a career working on electronic circuits, some of which were so large and complicated that the circuit drawings alone occupied a three inch thick, three ring binder. And those binders were FULL. Instructions and parts lists were in separate binders. Not bragging, just a fact. The only way that these circuit drawings were ever presented was with SCHEMATIC drawings. They did not use ladder drawings. They did not use pictorial drawings. They did not use other styles. They used schematic drawings.

And those schematic drawings were always organized so that the circuit flowed in a LOGICAL manner, usually from upper left to lower right. Or all the inputs were on the left and all the outputs were on the right. And all connections to a component that are related to a single function that component performed were in the SAME location, again usually with the inputs on the left and outputs on the right. If a relay was used, then the coil and the contacts were drawn right next to each other so there was no confusion as to where the other parts of it were. If an IC or a section of one was used, it was drawn as one block, again with ins on the left and outs on the right. You could see it all at a glance.

When you have to understand a circuit, that is simply the very best way to have it presented. Hands down. If those complex electronic devices that I had to work with were drawn in the manner that most industrial circuits are, I would have had to spend at least ten times as much time trying to follow them. I simply do not understand why there are so many pictorial or ladder or other forms of drawings that only confuse and make tracing the circuit a lot more difficult.

I just tried to read a post by someone who was asking how to connect a motor to a drum switch. His hand drawn circuit was OK as far as it went but he also posted the image of a professionally(?) drawn one from Daton that would have taken me a much longer time to understand than the whole thing was worth. It was drawn using a combination of pictorial and schematic symbols. It did not have any organization other than perhaps the order in which the terminals appear on the terminal board. Where is the logic in that? It would be better to draw a readable drawing and then number the terminals on that drawing, left to right and then build the motor with that terminal numbering. That is exactly how I HAVE DONE similar and much more complicated drawings for designs that I was making. I did it both for future people who would have to understand it and also for myself when I went back to that drawing the next day. Are they deliberately trying to have people burn up their new Dayton motors?

Why are these drawings made absurdly difficult to understand when there is a system that works so much better?

Why?????

Rant mode: Off.

I can't possibly give a competent answer about electrical schematics because I work with mechanical designs. I did revise a number of electrical schematics at my last contract position and insisted that the EE double check my corrections. Going through the 3 ring binders the EE often had commentary about how others had created the schematics and the standards used for layout/flow/representation. From what I could gather:

1) Standards employed for creating schematics have been revised over the years and not everybody keeps up
2) Much like mechanical drawings, standards exist but every company uses "house rules" that may even have incorrect nomenclature
3) The EE struggled with revising to current standards while realizing the need to have a resemblance to older schematics so as not to confuse anybody that had to work with the old and the revised drawings at the same time.

That may not explain much (if at all) but, to me, it does seem to be consistent in similar issues with mechanical drawings.

We use schematics heavily in pipeline world, they're called piping and instrumentation diagrams or P&ID's.

Not really sure how else you'd layout fluid flow diagrams?

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I think the simplest explanation is you can't force a person to do anything they don't want to do.

Case in point, a co-worker a couple jobs ago where I was working as a "manufacturing engineer" would draw/design/model up an entire job, then second guess himself and start over. At the time, we were making fixture desings and stuff for "upcoming" jobs, and we had no idea if/when they would happen. I tried to talk him out of over-engineering things that may not even come to pass, but he refused and would spend weeks doing things to the smallest detail.... guess what? We both got 'laid off' from that job after about a year and I don't think 1 single part/fixture layout ever got made. (< that wasn't his fault, but the point is people can be stubborn no matter how much you reason with them)

Perhaps they were trying to dumb it down to a pictorial view because they didn't know or understand their audience.

I strongly recall how grateful I was for the SAMS schematics during an earlier attempted career as a hi-fi tech.

Not a clue, but I've got the same complaint. Another pet peeve is schematics where the designer reached the connector to something and said, "Well, my job is done." Long ago, when I did this stuff, I'd always add a page with the pinouts, wire colors, model and description, for whatever it was the circuit connected to. Could have been motors, sensors, lamps, actuators or whatever. Saved a huge amount of time for the people actually working with the stuff, often me.

Yup, yup, & yup.

Have drawn schematics, worked with them, then did piping, and then powerline type
"1 lines"..... all seem to follow different rules, and then some "just make it up as they go along".

I think it's a combination of a number of things (1) not knowing how to do what you are asking, (2) knowing going how but not very good/lazy (3) project schedules/managers/engineers that don't value documentation.

Creating readable, logical drawings that clearly communicate the design is an art that can take longer than the design itself.

I see this in my work where clients value how fast they can get their product to market and documentation is sometimes seen as a hindrance to their goals.

GOOD question. I have run across plenty of those infernal things myself! More apt to leave one scratching one's head than quickly getting to the nitty gritty.

When I started working on machine controls back in the 70's most machine tool builders adhered to the same basic electrical standard schematic techniques. Of course it was almost entirely relay logic with discrete physical components, so the logic was inherently in the drawing. With the development of integrated circuit boards and later, programmable controllers taking over the functions of physical relays and switches, it became harder to represent the circuit as circuit boards are more or less "black box" components, and similarly programmable controls don't always provide easy access to ladder logic.

Aside from the fact that most manufacturers who employ such devices see the circuitry and/or programming as proprietary, or don't want people mucking about with it for liability reasons, the electrical representation of comprehensive control schematics is pretty rare. It may be in part a laziness on the part of manufacturers, but is also due to how differently controls work now than 40 years ago.

I see both sides of the argument....I gotta tell you, a lot of schematics are unintelligible. The symbols used are often from different 'bibles' and more importantly, have no particular logic behind them. Schematics are a language unto themselves, and if you don't speak that language, you're in hot water.

Sometimes, a picture is worth a thousand words. Sometimes, words are better than pictures or lines on paper.

A truly good schematic would assume the reader knows 'nothing' and can get from point A to point B from the information on the schematic. A lot of schematics don't cut it.

Even better, a good schematic would include some verbage..... "This schematic shows the power flow when the machine is in reverse. A capacitor (C1) is placed in series with the output of the transformer (X1) to allow the motor to roll at slow speed. A diode is used on the output of terminals A/B/C to prevent the resistor (R1) from overloading when the capacitor (C1) discharges.

In other words, explain what the goal is and what each piece is bringing to the party.


The hardest thing to figure out is how something works when you don't know how it's suppose to work.

You all are missing one major contributor to the mess . . . and that is Automated Database driven CAD packages for schematics.

Each component is entered into a database with connections defined, terminal blocks specified, and wire labels generated and then the whole thing is barfed out by an algorithm. Now this does make it easier to make revisions and have all cross references automatically update. But, the old hands that know how to produce beautiful schematics want nothing to do with this approach and the younger guys can’t understand why an electrician can’t figure out his drawings to do an install.

I went through a set of prints last night and marked them up and sent them back to the engineers that created them . . . I am certain I will get push back in the form of “The software won’t put the labels in like that” and “the software won’t line the field terminal blocks up like that”. To which I will respond “Then don’t use that feature of the software!”

The *real* answer to this question is obvious with a moment's thought. The companies *do* make accurate, readable schematic
diagrams - for their own use. That's how they develop a product and put it into manufacture.

They just don't make that information available to the end user, there is no profit in that. If you had that, you could fix their broken
stuff and then would not buy their *new* stuff.

See also: "proprietary ICs"

jim rozen said:

The *real* answer to this question is obvious with a moment's thought. The companies *do* make accurate, readable schematic
diagrams - for their own use. That's how they develop a product and put it into manufacture.

They just don't make that information available to the end user, there is no profit in that. If you had that, you could fix their broken
stuff and then would not buy their *new* stuff.

See also: "proprietary ICs"

Click to expand...

Except if you talk to the people who work there, they'll tell you they also can't understand half of what they produce.

I have seen the quality of "engineer" the collage systems have produced in the last 10 years Purdue, Ohio State University I think the Universitys have forgotten what they are supposed to teach. I had a "engineer" with an MBA in engineering ask me if I could weld delrin to stainless steel and was not joking....

As far as I can tell the only thing the all could do is draw pretty pictures in solidworks.

A very famous man, someone far smarter than you or me, once said "If it can be imagined, it can be done". So, of course you can weld Delrin to stainless steel....you just need to imagine better.

jim rozen said:

The *real* answer to this question is obvious with a moment's thought. The companies *do* make accurate, readable schematic
diagrams - for their own use. That's how they develop a product and put it into manufacture.

They just don't make that information available to the end user, there is no profit in that. If you had that, you could fix their broken
stuff and then would not buy their *new* stuff.

See also: "proprietary ICs"

Click to expand...

I do not believe they even produce them internally. No need to, as long as the connections are all present, the automated PWB layout program will handle it OK.

Then also, with some exceptions, the boards are really not INTENDED to be repaired. If the MFGR was smart, they included a verification system in the board, but most do not. Then you have to do either a test point based, or "Input vs output" based check system, so that you apply a certain set of inputs, and verify that the outputs match what they should be.

That "input vs output" approach makes it a simple "this one works" check, where nobody really needs to go through the schematic. The test point based checks are more than is necessary, since nobody is going to repair it at the component level anyway.

So there is really no need to provide schematics for complex systems.

In most cases the field tech is going to determine, rightly or wrongly, that PWB #4 is bad, and substitute another one. That either fixes it or not.

The system works fine as long as "PWB #4" is available as a spare. When it is not, then you are in trouble, you cannot fix the unit without a lot of trouble at the very least. If the part that is bad is a programmed part, then you may be completely screwed.

So, what is left?

Just the wiring diagram, which the manufacturer often DOES provide.

Incompetence.

The people doing the customer documentation probably wouldn't know a schematic from a flow chart. They tend to be "technical writing" experts, which often means a journalism major who couldn't get any other job.

During my career I had quite a few go rounds with such over usable information vs document style. A pretty document is useless if it doesn't convey necessary information.

Are there industry standards/guidelines for schematics? I ask because I occasionally need to document something I've put together just so I can figure out what I did when the time comes to fix it or modify it, or sometimes it's to document something I'm repairing that I have no documentation for. I usually scratch something out on a legal pad then photograph it and put the photo in the documentation file but I'd hate to have to show it to someone else. The first attempt is usually horrible and looks like a 2nd graders sketch. What would you do in this circumstance? I just want something presentable and easy to modify if needed. Once upon a time I had Verio which did flow charts and graphs which sort of worked for this, but that morphed into something completely different. I'm Electronically Challenged so I'm usually struggling to understand what I'm building at the same time I'm trying to document it.

There are accepted GD&T standards, is there the same thing for schematics?

I have had to work with the 3 ring binder schematics and I hope they choke on them. Biggest pain I ever saw. Technicians should know the intent of the use and utilize the schematic for reference. There are endless revisions to equipment and the schematics cannot keep up.

In house design has changed with design programs that merge wiring/signal flow with hardware/circuit board traces. The programs are outrageous in price. I checked on a viewer (only a viewer!) program and it's $6000 a year.

Many manufacturers copy proprietary design work and profit from doing so. One way to screw them over is purposely scramble documentation, even to the point of changing the names of connection points marked on hardware.

Remember to look for the intended use, what environment does it occupy, how is it to perform in the user's environment, and keep the basics of science (physics) in mind. Then you can tackle just about anything.

These folk are called technicians and they are priceless.