Critical thinking

[Enzo]

Oh yeah. I have a customer who plows snow. There is a small box on the dashboard to control the plow with a joystick. He brings me the box when a microswitch under the stick fails. "They want $300 for these boxes."


Everything we work on is a system of some sort, it is a process. What concerns me is the inability of some to propose an if>then proposition, or suggest a systematic approach to finding the problem. Instead we get "my reverb doesn't work, I already tried new power tubes." It requires an analytical approach to follow a signal path or a step by step path to whatever the problem might be.

[J M Fahey]

@ hasserl: incredibly useful post, and fully applies *everywhere* The few "mechanical" examples are just that, examples.
The logic behind troubleshooting is universal and the same.
@ Enzo and others: yes, the best approach is as checking for *systems* not working.
This will later lead , in many cases but definitely not all, to "bad parts".
Going the opposite way, "testing parts" without further analysis is slow, tiring and very frustrating.
In many cases you can even substitute *all* parts and yet not solve a problem. Go figure.

The analysis method is universal.

[Techknowman]

Electronics is a vocational dead end. I have been watching for teaching positions in electronics in this area. The local junior college here no longer even teaches it. COmputer tech guys learn how to see if a power supply is working ot not, that's about it. VOltmeter 101. I had zero interest in teaching it at the high school level, because I wanted to teach motivated people. SHop class was not a high priority to high schoolers. At the college level, most people there are motivated to learn, and are paying to be there.

I got my start in high school, we had an "industrial electronics" class back in 84. I learned ohms law and how to calculate how many volts it would take to kill me. Everyday the first thing we had to do was wet our fingers and take an ohm reading and calculate the volts needed to kill us. Anyway we had 6 students in my class. only 2 of us were there to learn the others were there as a place to ditch other classes, they spent most of there time making learning for the 2 of us harder. I worked on old tubetype b&W tv's and a few color ones from time to time. after school i was able to get to work at a local car and home stereo shop. They were a authorized service center for just about every major brand of audio equipment made. I worked there for 2 years and then moved to a local CB shop and learned to repair / tune-up cb's and work on audio gear.
as just a bench guy I never really made good money and so I pulled up stakes and moved to the big city where I worked for a big name outfit for awhile but never made much of it.
In 91, through a friend, I got a job working as an industrial service tech for a food products company, working on process controls, meters, gauges and later statistical weighing and packaging machines.
Later working on metal detectors and other different stuff. I learned programming PLC's and controls repair.
Through the years I went on to design industrial control systems and now work for a firm building custom automation controls and embeded systems.
And through all these years I have seen fewer and fewer people going into the fields I started in and am currently now in. Its almost a vacuum. Kids are in high school and all they get drilled into them is college when some are more practical to go to vocational schools, but most of those don't teach these fields.
If you want to get a degree in IT and starve to death you can. But if you want to learn electronics and such, its much harder to find.
My 3 boys, 19,25 and 26, come up to me from time to time and say " I sure wish I could repair things like you do" and I have tried to teach them but they lack the real drive and the logical training. They have been so corrupted by the instant gratification aspects of todays life that really having to "work" at something is almost alien to them. They can't really understand what I and others had to do a lot of to get where we are today and its not as easy as wishing.

[Enzo]

It is like anything else. learning to fix things good, learning to play an instrument, learning to play a sport well, etc. Everyone wants to be good at something, but few want to BECOME good at something. They want to skip that step where you work at it and gain experience. They look at what we do here as some task that can be shown. They don;t grasp that my "effortless" diagnosis of something is born of over 50 years experience. How can I learn to be as good as you at this? Well, start 50 years ago and...

I went to a pretty large high school near Washington DC. I took some electronics there in the early 1960s. (Still teaching tubes, not much on transistors then.) Our class was mostly us nerdy boys. There was also wood shop and especially print shop, where the real delinquents hung out. Back then, many of us were in the "college prep" track, but we had things like the print shop where guys could learn a real trade. There was also a track in the high school called "distributive education." That translates into learning how to work in a retail store. There was also quite a home economics area too, learning to be a housewife. Things are not like that now.


people write to the paper complaining that the school board wants to include some math in the general curriculum. They proclaim there is too much emphasis on going to college, when maybe that isn't the best thing for some. They equate math with "going to college." Don;t need math? How about this:

You have just bought an ounce of dope for $400, and you want to sell grams of it on the street. What is your cost for each gram? Well that is math folks. DOn;t tell me you only need it in college.

[Rhodesplyr]

Something that I notice, where I live, is what I perceive to be a general disdain for any activity that involves getting one's hands dirty. I live very close to where I grew up, and people used to mow their own lawns, which meant maintaining their own lawnmowers, etc... Not any more. They all have landscaping services that swoop in and do it all for them. God forbid that their children should have to endanger themselves using power tools or humiliate themselves by using a leaf rake. Recently, I've been seeing mobile car detailing services because, I suppose, vacuuming one's own car would be too traumatic. If their bicycle breaks, they take it to the bike shop.

The upshot is that kids that grow up in environments like this haven't the remotest idea how anything mechanical works.

[J M Fahey]

You have just bought an ounce of dope for $400, and you want to sell grams of it on the street. What is your cost for each gram? Well that is math folks. DOn;t tell me you only need it in college.

And not only that: "the other" Dealer outsells you: if you "cut" it too much "customers" feel cheated (and tell you so in a subtle way, trying to slip a switchblade between your ribs); if too little he outprices you; the "magic" cutting number is diluting it to 35%.

And your friendly corner cop wants 200$ a night to let you sell unmolested .... how much is the minimum daily sale to break even?
And to earn $300 a day? (Otherwise get a job at McD or whatever).

Yea, sure, "Math is useless for me".

Thanks Enzo for this posting.

[Techknowman]

You have just bought an ounce of dope for $400, and you want to sell grams of it on the street. What is your cost for each gram? Well that is math folks. DOn;t tell me you only need it in college.

yea math is used everyday, most just don't realize it.

[Neal]

More 'old guy' musings that may or may not be on topic:

The United States military seems to have (or had, anyway) the most efficient, common sense method of training young men. Old US Navy electronics textbooks remain one of the most popular resources for tube amp guys, for example.
My father was an airplane mechanic in WWII. He was a very good trouble-shooter, and was one of those guys that could fix anything. He once told me a little bit about his training:
"Our class of about 10 guys was in a big room, with an airplane engine on a stand. We were told to fix the engine. The instructor gave us each a clipboard, and then told us the symptoms of the faulty engine. We had to write down 10 things that could cause the engine's behavior, and circle the most likely cause.
When we got THAT right, only THEN would the instructor let us pick up our wrenches and approach the engine."

Makes sense to me. He also had a few choice opinions on today's diet fads, but I'll save those for another thread...

[Chuck H]

And not only that: "the other" Dealer outsells you: if you "cut" it too much "customers" feel cheated (and tell you so in a subtle way, trying to slip a switchblade between your ribs); if too little he outprices you; the "magic" cutting number is diluting it to 35%.

And your friendly corner cop wants 200$ a night to let you sell unmolested .... how much is the minimum daily sale to break even?
And to earn $300 a day?

I almost fell out of my chair laughing as I pictures my fifth grade teacher, Mrs. Robbins, reciting: "OK class. Timmy has $400.00 worth of dope. He will cut it to 35%... Officer Bob gets $200.00 a night..."

[Enzo]

Yeah, and I recall my Jr High school shop teacher, Mr Warner, who had a sign up front that said, "Don;t build your wall with putty full of goof-off sand." I can imagine him going over that deal.


people don;t even think, they give up first. You ask them what each bag of dope costs and they know what you mean. As soon as you refer to it as "X", they freak out and have no idea.


I've never worked on an aircraft engine, but I am pretty sure the problem is the transformer.


I remember a long time ago our kid had a neighbor kid over to play, I think they were playing Hungry Hippo. Geez, I am guessing close to 20 years ago, but that doesn't matter. There was this simple mechanism for the hippo to retract, involved a rubber band inside and what all. The band had popped off its hook. Here is this 8 year old kid looking at this simple mechanism, and looking around his environment for a tool to hook the band and stretch it back over its mount up under the hood. I instantly realized this kid had "tool sense." An innate understanding of need for tool and what that tool needed to do. It was faqscinating to watch. I mentioned it to the kid's mother, and I recal thinking at the time, this kid is a treasure. He could grow up to be a good mechanic or an engineer or a bunch of other things, but that small moment of talent I saw was something I so rarely see.

[g1]

I've never worked on an aircraft engine, but I am pretty sure the problem is the transformer.

Classic. But I think it may be the bias.
Hungry Hippo, battling tops, Ker-Plunk! If we couldn't fix our own toys, bikes, etc. it was wait till next Christmas.

[Chuck H]

I'm sure my story is like anyone else here. I had a pile of bike parts in my back yard. An actual bona fide pile. Maybe 80 cubic feet of parts. My brother (thirteen months younger) and I salvaged any bike we could scrounge. And we fixed a lot of other kids bikes. If one of our bikes was stolen we just went to the pile and built another one... Good old days.

[Enzo]

Maybe it is tool curiosity. To this day, if I want to clear my head and relax, I'll grab an old VCR or something from the junk pile and strip it down to the tiniest parts.

I remember working on bikes, turning handlebars around, changing seats, removing fenders, fussing with brakes and shifters. I never got so far as to build one from a heap, though. When i was a kid, bikes were one-speed, you back pedalled to apply the brakes. Then one day I got what we universally called an "English Racer" bike. That was a bike with THREE, count 'em, THREE GEAR speeds. There were hand levers for the brakes. You pedal backwards and they spin freely, making a clicking sound. Very high tech for us back then.

[Brad1]

BTW...

...I know a few "critical thinkers". They're critical of EVERYTHING!

A recent example of "assumptions". My Mom called. My niece had stuffed a huge, long foam-filled pillow into her washing machine, and tried to wash it. As can be expected...the machine did the "Unbalanced Tango" in the laundry room.

Then...before she could get to it...it stopped. Full of water. They waited until I got there, and I wrestled the 150lb. pillow out of the tub...fighting me all the way out.

Tried to set it to spin/drain cycle to get rid of the water. Nada. There was clicking noise from the timer, but nothing would happen. "UH-OH!" So, I set it to wash, to see if ANYTHING worked. That actually started up. "What the...?!"

I'm standing there scratching my head..."Hmmmm....could be....the extreme motion of the tub knocked something like a wire loose inside? Could be....something mechanical got destroyed?"

Took a break, and contemplated it over dinner.

Then it occurred to me. I didn't hear the little door switch clicking when I raised and lowered the lid. Stuck a screwdriver in there to operate it..."Man...this doesn't feel right." Was getting ready to disassemble the machine when I discovered I could loosen it up and remove it through the top, between the cover and the tub. Took it out, and it was a plastic two-part module with the lever molded to attach to both ends. The module was separating, not allowing the switch to work. So...I found some plastic glue and a clamp, clamped it together and glued the crap out of it. Let it sit until the next night. Reinstalled...problem fixed.

Mom was ready to call an expensive service guy, who would have charged her...what..$50+ for that, and $100 labor?

Anyway, the point is that at first I ASSUMED that it was something else, because it didn't occur to me that the lid-switch had anything to do with it. I COULD have spent hours tearing into that thing, and THEN found it. Now that I looked at it, I can only assume what actually happened. MAYBE that over-sized pillow was sticking out of the tub at the top, and when when the tub was spinning around at high speed and bouncing around, centrifugal force caused that pillow part to stick out and beat the crap out of the switch when the tub tilted that way?

Just thought this was another example of of "Critical Thinking". Kinda.

Brad1

[Enzo]

Oh, we all out think ourselves from time to time. I can think of any number of times that I was working on something and just totally puzzled and clueless. If I had any hair, I'd have been pulling it out. So like any experienced pro, I set it aside to come back later with a clear head. And most of the time I have one of those "Oh, is THAT all it was?" moments.

But Brad's story makes the point, look at the situation from a system level, think about what it is doing, and make up a plan of attack. If we are not sure if something is involved or not, we FIND OUT.