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In 1958 when this "Customer
Cues" installment of John T. Frye's "Mac's Service Shop" series of
technodramas™
in Radio & TV News magazine, color television was a relatively new
phenomenon. The first commercially sold color TV set - the
Admiral C1617A - went on sale at the very end of 1953. The
NTSC (National
Television System Committee) approved the first standardized specification for a
composite color television composite signal (color, gray scale, audio,
brightness, synchronization) earlier that year. It allowed the same signal to
work with both black and white (B&W) and color receivers. A lot of research went
into making sure the viewing public was happy with their sets, using polls,
hands-on instruction and publications on how to properly adjust tuning and
picture controls, plus tips on installing outdoor antennas and running the twin
lead transmission cable down to the set. Of course the proper way to fiddle with
the built-in "rabbit ears" antenna was covered as well. I don't think any
official pamphlets included mashing tinfoil onto the rabbit ears in complex
patterns as many people did - truth is, it must have worked in some cases. In
the story, Mac schools Barney on the situation.
Mac's Service Shop: Customer Cues
 By John T. Frye
It was October and the landscape was aflame with "Living Color." The morning
was a perfect setting for the fall beauty. Barney stood for a moment before entering
the shop looking at the morning-glory blue of the sky overhead, breathing deeply
of the cool clean air rising from the dew-wet grass, and noting appreciatively
the way the sun splashed its warm light on the red, green, purple, and russet leaves
of the trees across the street. He heaved a little sigh and turned and entered the
shop.
"Hey, boss," he greeted Mac, his employer, "Nature really has the color control
turned full on today."
"Yep," Mac said as he flipped a little a.c:d.c. chassis over on its back; "and
did you notice that she always has the hue control set just right?"
"That's more than I can say for a lot of our customers," Barney remarked as he
took his shop coat from the closet. "Most of them can't even tune a little radio
like the one you're working on."
"Why do you say that?" Mac asked with a quizzical look.
"Cause it's true. You know what a sloppy job of tuning ordinary black-and-white
TV sets most people do."
"No I don't," Mac demurred. "People usually have a little trouble right at the
beginning, but it's been my experience that most of them learn to do a pretty creditable
job of adjusting the set, especially if the person who installs it does his job
and gives them adequate instructions. They usually do not have the foggiest notion
of what turning each knob actually does and quite often they cannot tell someone
else how to adjust the receiver, but still and all most people manage to adjust
their own sets so as to produce a good picture. They just keep twisting the knobs
and watching the picture and listening to the sound until they stumble on a procedure
that gets results. Eventually they act almost instinctively to correct any picture
fault that shows up."
"One man's opinion!" Barney grunted.
"It's more than that," Mac insisted. "Recently a group at Iowa State College
made a study for the FCC of just how well the average TV viewer adjusted his receiver
and they were surprised to learn he does a darned good job of it. They found out
he was just as capable of distinguishing between a good and bad picture as were
the engineers- something few technicians will ever believe -and the great majority
of viewers could set the controls to get the best possible picture."
"Maybe so," Barney admitted grudgingly; "but they certainly talk a lot of gibberish.
They call a ghost a 'shadow,' confuse the contrast and brightness controls, and
talk about the picture as being 'soft,' 'hard,' 'smooth,' 'grainy,' and goodness
knows what all else."
"No law says they have to use our technical vocabulary. Keep that in mind. Instead
of laughing at their terms, try hard to understand exactly what they mean. And along
the same line, when you're making a house call, always try to maneuver the set owner
into turning his receiver on and adjusting it if you can."
"Why?"
"For several reasons. For one thing, that relieves you of the necessity for hunting
out the right controls. We know there's no reason in the world why a technician
should have in mind the exact location of every control on hundreds of different
models of TV receivers, but the customer can't grasp this. When he sees you fumbling
around for the knob that turns the set on, he jumps to the conclusion you don't
know much about his particular set."
"I'll buy that."
"Also, if he IS misadjusting his receiver, you have a chance to catch him at
it. Of course you never tell him he has been doing something wrong, especially if
his wife's in the room. You simply do it right and make sure that he sees how you
do it. I am 'agin' the tendency of many technicians to regard their customers as
being one cut above complete idiots. I know this makes for a lot of very funny
smart aleck talk among technicians - telling what stupid
boo -boo's their customers pull - but it is a dangerous pitfall for a technician.
He wants the respect of his customers, but it's pretty hard to get respect unless
you give it. And it's a cheap feeling of superiority you get from anointing yourself
with the ego -salve of narrow technical knowledge. Insist on doing that and you
are laying yourself wide open to being considered a moron by the doctor, lawyer,
chemist, jeweler, automobile mechanic, and hundreds of other trades and professions."
"Don't worry about me," Barney said. "Now and then I get a little impatient because
a customer has some wacky electronic idea or seems a little slow about grasping
what I'm trying to tell him; but I don't pop off about what I think. Not to change
the subject, how are you making out with that little receiver. I put in an hour
on it last evening without finding out what was producing that funny squelch effect."
Before answering, Mac tuned the little receiver across the band. There was absolute
silence between stations with no trace of normal hiss; but when strong stations
were tuned in, the reception seemed normal.
"What all did you try?" Mac asked his assistant.
"Well, a gassy tube will often cause that; so I changed the mixer, i.f. tube,
and the combination detector - a.v.c first -audio tube. No dice. Then I decided maybe
the audio coupling capacitor was open until a strong signal temporarily bridged
the break, but paralleling it with a good capacitor made no difference. Next I checked
the a.v.c. resistors to see if any were open or had seriously changed value. All
were OK. By then it was time to knock off."
"And if I know you, you dropped the solder gun at the first stroke of the clock,"
Mac growled. "Let's get out the signal tracer."
The signal was easily traced through the mixer, the i.f. amplifier, and right
up to the secondary of the second i.f. transformer; but there it disappeared. That
is, it disappeared until a strong signal was tuned in. When a weak signal was being
received, the signal was present across the transformer primary, but it could not
be picked up across the secondary.
Mac laid aside the signal tracer probe and flipped on the v.t.v.m. Carefully
he checked the voltages at the pins of the 12AT6. When the probe was touched to
the diode detector plate, a small positive voltage was noticed. Mac tried another
tube without changing the condition. Then he picked up the diagonal cutters and
cut the lead going from the i.f. transformer secondary to the diode plate. The voltage
appearing on the cut transformer lead became still more positive. Quickly and deftly
Mac cut loose the leads of the small slug -tuned transformer and lifted it out of
the chassis. He switched to the ohmmeter and measured the resistance appearing between
the two windings. An easily measured resistance of several thousand ohms was indicated.
It took Mac only a few minutes to get a duplicate transformer from stock and
install it in the receiver. Barney always enjoyed watching his boss work. The man's
big hands moved as confidently and surely as those of a surgeon and there was absolutely
no waste motion. The wires were connected and neatly soldered so that the new solder
connections could not be detected from those done at the factory.
As soon as the set was turned on, it was apparent the trouble had been found
and eliminated. The receiver had lost its unique squelch effect. Weak and strong
stations both were tuned in smoothly. Mac carefully aligned the whole i.f. system
and touched up the oscillator and r.f. trimmers. The receiver worked perfectly;
so he wiped out the plastic case and put the chassis into it.
"Oh don't look so smug!" Barney erupted. "How did the i.f. transformer produce
that odd effect?"
"You should be able to figure it out. What would be the effect of that leakage
between windings?"
"I suppose the 'B-plus' on the primary would put a positive potential on the
diode plate."
"Right. And that would make the diode conduct and virtually short-circuit the
secondary until enough signal appeared across the secondary to override the positive
bias."
"What caused the leakage?"
"I think it is a little moisture that gets into the capacitors molded into the
base of the transformer. At least I have been able to cure it temporarily by baking
the transformer for a few hours under a heat lamp."
"So-o-o-o! You knew all along what was wrong. How come you went through all that
rigamarole with the signal tracer and the v.t.v.m.?"
"Because I wasn't sure. Actually, this condition is more often brought on by
a defective tube than it is by an i.f. transformer; but during the hot summer months
I noticed a small rash of this particular kind of transformer trouble. When it happens
to an input transformer, the symptom is more likely to be low gain and an intermittent
crackling noise. I used the signal tracer and the v.t.v.m. because I always try
to follow a logical procedure in running down an unusual symptom."
"We surely are doing a lot of work on these little receivers," Barney said. "I
believe people are listening to radio a lot more than they did a year or so ago."
"That's right, but it's a specialized kind of listening. The kids listen to a
favorite disc jockey; the woman listens to morning programs in the kitchen; Pop
listens to the ball games. And incidentally, it does not hurt a bit to inquire casually
what stations are favorites with the family when the set is brought in. Since that
new station has opened up in Garden City on 1600 kc., you want to be sure and see
that the receiver will tune up to it. By the same token the station on 560 carries
the ball game and you want to be certain it can be picked up. A lot of people listen
to a religious station around 1110 kc. You can make them happy by peaking the set
up on that frequency. The same goes for other pet stations. Ideally, of course,
the receiver should be made to track perfectly clear across the band; but practically,
you can usually make a noticeable improvement on a particular frequency by careful
peaking of the r.f. trimmer at that frequency after you have done the best you can
to get good tracking."
"Gotcha, chief!" agreed Barney.
Posted April 17, 2024
Mac's Radio Service Shop Episodes on RF Cafe
This series of instructive
technodrama™
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 April 1948 in Radio News
magazine (which later became Radio & Television News, then
Electronics
World), and changed its name to simply "Mac's Service Shop" until the final
episode was published in a 1977
Popular Electronics magazine. "Mac" is electronics repair shop owner Mac
McGregor, and Barney Jameson his his eager, if not somewhat naive, technician assistant.
"Lessons" are taught in story format with dialogs between Mac and Barney.
Color and Monochrome (B&W) Television
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