Summer begins this week in the northern hemisphere, and winter begins south of the equator. Counterintuitive to northerners not familiar with the geometric cause of seasons (axis tilt) is that the Earth is actually closest to the sun in January than it is in July. Our orbital path is nearly circular, with an eccentricity of just 0.0167. Anyway, I thought the onset of summer would be a good time to post this installment of Mac's Radio Service Shop entitled, "Summer Seminar." Typical of author John Frye's techno-sagas, more than one theme runs through the story. It begins with shop owner Mac admonishing technician Barney for throwing away a faulty selenium rectifier when he knows there is an industry-wide shortage on supplies of the element and the bad components should be submitted for recycling. Fretting over as common an element as selenium might seems ridiculous in these times of plenty, but resources were more difficult to come by at the time. Prospecting for, extracting, and processing just about every element in the periodic table is almost a boring exercise. However, with the rate at which elements are consumed in the manufacturing of such a vast amount of products as are used nowadays, some scarcity is being reported in the news. Helium, the second most abundant element in the universe, has been mentioned. Yttrium (used in oscillators) and neodymium (super magnets) supplies are now being threatened by trade wars. Others have been identified as well. The threat of scarcity is not for lack of known deposits but because of poor planning on the part of nations that have knowingly risked their own sovereignty and independence by facilitating - even directing - the concentration of production exclusively offshore while eliminating domestic capacity for production. In the case of the U.S., the resources needed to protect our economy and freedom can be mined within its borders, but it will require immediate commencement of production operations.
Mac's Radio Service Shop: Summer Seminar
By John T. Frye
The soft little breeze drifting through the wide open doors of the service shop felt good to Mac and his helper, Barney, as they worked away at the bench on this warm June afternoon. Mac glanced up from the new TV tuner he was installing in time to see Barney toss a selenium rectifier he had just removed from a three-way portable into the trash barrel.
Making sure he had Barney's attention but without saying a word, Mac fished a dime from his pocket and nonchalantly flipped it into the barrel.
"Hey! You popped your cork?" Barney asked anxiously. "Wasn't that a dime you just threw into the barrel ?"
"That's right. If you can throw away money so can I."
"What do you mean: I throw away money? My mother never had any stupid children."
"Didn't you just toss a selenium rectifier into the trash barrel?"
"Sure, but it wasn't any good." "Remember my telling you selenium is in short supply and that rectifier manufacturers have asked us to save old rectifiers so the selenium can be reclaimed?"
"Yes, now that you mention it, I do recall your saying something about that. In fact, I also have a hazy recollection that our parts salesman mentioned he would give us ten cents for every old rectifier we turned in, no matter what the size. It just sort of slipped my mind."
"Well, just sort of slip into that trash barrel and fish out the rectifier you tossed in as well as any others you may have discarded when I wasn't looking. And while you're in there, you may as well recover my dime."
"OK, Boss," Barney said with a broad grin on his freckled face; "and you certainly made your point. I may forget Ohm's Law or even the color of my Margie's eyes, but the sight of a Scotsman throwing away money is something I'll never forget."
Fortunately the barrel had been dumped only a day or so before; so recovering the rectifier and dime was easy. Barney placed the rectifier in a cardboard carton and facetiously marked the outside "Old Diamonds, Old Gold, Old Selenium Rectifiers," Etc." and placed it beneath the bench. Then he turned his attention to what Mac was doing.
"Did lightning clobber that tuner?" he wanted to know.
"Yep, and it did such a good job that a complete replacement is the only practical repair."
"Another case in which the lightning arrester obviously fell down on the job," Barney offered. "Sometimes I think those things are just a waste of money."
"Lightning arresters are something like kids," Mac said with a tolerant smile. "People expect more out of them than they can deliver, and they get a lot of blame they do not deserve. A properly installed lightning arrester with a short direct lead to a really good ground will do an excellent job of protecting a TV set from surges induced into the antenna and feedline by nearby lightning strokes, but only a fool would expect it to furnish protection from a direct stroke to the antenna itself. Neither will a lightning arrester afford protection against damage by lightning that is going from the set into the antenna."
"From the set into the antenna!" Barney repeated. "What kind of crazy talk is that?"
"It's not crazy at all. In fact, most of the lightning damage in this area is caused by surges going up the feedline rather than down it. Keep in mind that the majority of the antennas around here are of the yagi-inspired type that has the driven element directly connected to the boom, the boom connects to the mast, the mast connects to the tower, and the tower is grounded. In other words, the antenna is actually at ground potential.
"Now let's review what happens when a stroke of lightning sends a surge along the 'hot' wire of the power line to which the TV set is connected. This surge comes in on one side of the line cord and promptly goes through the line bypass capacitor, if one is present, to the chassis. If no capacitor is used between the line and the chassis, as is often the case, the surge may jump the switch and reach the chassis by breaking down the insulation between the power transformer primary and the core or one of the other, grounded windings. Once on the chassis it goes through the grounded center-tap of the antenna coil connected through the turret switch to the antenna terminals, up the lead-in to the antenna, and back down the mast and the tower to the ground, where it had been heading all the time.
"When you look at the charred coil and the melted turret contacting fingers, there is no way of telling which direction the surge was travelling when it passed through them. In fact. the natural conclusion to reach would be that the damage was done by a surge coming down the feedline; but actually the chances are that it was going up the feedline as I described. Whenever you are checking out a set with these symptoms, be sure and test for a short-circuit between both sides of the line cord and the chassis before letting the set out of the shop. It is a good idea to disconnect the resistor often found between one side of the line and the chassis while making this test so that a high value of leakage, that can quickly change to a low value when the line voltage is applied, may be spotted. If there is a short-circuit between one side of the line and the chassis, there will be a fifty-fifty chance of burning out another antenna coil as soon as the antenna is connected and the set plugged in. If the side of the line cord that is shorted happens to be plugged into the grounded side of the light line, nothing may happen until the plug is removed and turned over; but then the smoke will roll or the fuse will blow."
"The best insurance against lightning damage would seem to be to yank the line cord whenever a storm is approaching."
"Truer words were never spoken. Putting all your trust in a lightning arrester is like barring the attic window against burglars and leaving all the rest of the doors and windows wide open. If all our customers followed our advice and pulled out their TV line cords when a thunderstorm approached or when they left home for any length of time in the summer, our lightning repair business would drop to a very low figure."
"Then why tell 'em?" Barney demanded.
Before Mac could answer an elderly lady entered the shop. Miss Perkins was on vacation; so Mac went into the front part of the shop to give the customer her small clock radio.
"Here you are, Mrs. Nelson," he said.
"I found the noise you mentioned, and a new tube took care of that; but I'm puzzled by your saying the radio was dead. It started off as soon as I turned it on, and I have kept it running for two whole days without any cutting out. Could it have been possible you did not have the clock switch turned on? This is one of the few sets I have come across that uses two turn-on switches connected in series: one on the volume control and one on the clock."
"You mean those little knobs on the clock have something to do with the radio?" the little old woman asked with a puzzled expression.
It quickly developed the radio was a Christmas present and that the donor had not explained how it worked. The owner had never known there was any connection between the clock and the radio. To her, a clock-radio was simply a clock and a radio. Fortunately, the clock switch had been left in the "Manual" position; so the switch on the volume control had served to turn the radio on and off. An inquisitive visiting grandson had apparently turned the clock switch to "Off," where Mac had found it; and so the volume control switch could not turn on the set.
Gently and patiently Mac explained the working of the combination. Not only did he show her how to set the clock controls so that the radio would be turned on or off at a given time, but he also made certain that she understood the clock switch had to be left at "Manual" if she wished to use the volume control switch for turning the set on and off.
"Boy! How dumb can you get?" Barney sniggered after she had thanked Mac warmly and departed with her set.
"Let's have none of that kind of talk!" Mac said sternly.
"There's no reason why she should understand the workings of a clock-radio without instruction. And there are dozens of fields, from churning butter to diapering babies, in which her knowledge and experience would make us both look like real dopes. Let me make it clear for once and for always that in this shop our Senior Customers are to receive every courtesy, consideration, and kindness."
"I'm sorry, Mac," Barney said with a red face. "I know better than to say anything like that."
"Sure you do. I heard you griping the other day how color TV, printed circuits, u.h.f., and transistors were piling in on us faster than we could grasp them; but did you ever stop to think what a bewildering array of basic new inventions and discoveries have come into use during the span of that woman's life? Electric lights and power, automobiles, airplanes, radio, TV, motion pictures, jet propulsion, antibiotics, atomic energy - these are just a few of the things she has had to understand and learn to live with and use during her lifetime. It is truly wonderful that she and her contemporaries have been able to take all this in stride."
"That's a fact," Barney warmly agreed.
"And while we're on the subject, I want you to give these older customers of ours a little special treatment. I'm not saying this just out of sentiment. As the normal life span increases, elderly people are becoming more and more important to our economy as a whole; and they play a particularly important part in the radio and TV service picture."
"To active working people, radio and TV are just a couple more forms of amusement bidding for attention; but to many retired persons they constitute practically the only form of entertainment regularly enjoyed. This makes the radio receiver or TV set assume an importance not always understood by the service technician. It's hard for him to comprehend how lonely an elderly person may feel when his or her set is out of order; yet both of us have heard these people say it's almost like having someone dead in the house when the radio or TV is on the fritz."
"Then you want me to make every effort to return old people's sets in a hurry."
"That's the ticket. I hope that we can do a little plain and fancy record breaking in this part of our servicing operation.
"More than that. When you return a set to them, make sure they know how to get the most out of it. Try to have the owner tune the set while you watch. If he's doing anything wrong, tactfully show him how it should be done. You'll find these people are deeply grateful for any help you can give and for your intelligent interest in their problems. They make loyal, highly-vocal customers who will provide us with an astonishing amount of effective word-of-mouth advertising once they are convinced we are honest, capable, and friendly. Be sure and note that word 'friendly.' It is important in dealing with any customer, but friendliness is especially appreciated by elderly people."
"Gotcha!" Barney exclaimed as he made an understanding circle with his thumb and forefinger.
Mac's Radio Service Shop Episodes on RF Cafe
This series of instructive stories was the brainchild of none other than John T.
Frye, creator of the Carl and Jerry series that ran in
Popular Electronics for many years. Mac's Radio Service Shop began life
in Radio & Television News
magazine (which itself started as simply Radio News), and then changed
its name to Mac's Service Shop after the magazine became
World. 'Mac' is electronics repair shop owner Mac McGregor, and Barney
is his eager, if not somewhat naive, technician assistant. 'Lessons' are taught
in story format with dialogs between Mac and Barney.
Posted June 17, 2019