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June 1959 Electronics World
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
from
Electronics World, published May 1959
- December 1971. All copyrights hereby acknowledged.
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Before reading this 1959
"Mac's Service Shop" episode, I had never heard of a person whose
troubleshooting method was to pull and test every tube referred to as a "Bulb
Snatcher." John Frye authored scores of these technodrama articles for various
electronics magazines from the mid 1950s through early 1970s. This one appeared
in Electronics World. Having spent my hitch in the USAF as a technician
working on airport surveillance and precision approach radar systems produced in
the early 1960s, I did a good deal of tube pulling while troubleshooting the
circuitry. Not being highly experienced at the time, I admit to having been what
Mac referred to Barney as - a "bulb snatcher." A lot of times, replacing tubes
fixed the problem - especially when a total failure had not occurred - and
getting the system back on the air in short order took precedence over
displaying superior circuit knowledge and troubleshooting capabilities.
Mac's Service Shop: Bulb Snatching
 By John T. Frye
Barney was trying to wrestle a tube from the radio he had just turned
off. Suddenly it came loose from the tight grip of the socket, spun from between
his scorching thumb and forefinger, and went flying across the service shop. It
hit the wall, caromed off a TV cabinet, fell to the floor, and came to a spinning
stop at Barney's feet.
"Didn't break!" he announced triumphantly as he stooped over
and picked it up.
"Which is like gloating that your crystal isn't cracked after
you've bounced your watch on a tile floor," Mac, Barney's employer, remarked sarcastically.
"A transistor may take that kind of punishment but not a tube. Throw it away and
put in a new one. Charge it off to the shop and to your butter-fingers." "
If it
tests OK can't we still use it Barney asked.
"Nope," Mac demurred. "You know how
often we get in a set with a cracked cabinet and a story that goes something like
this: 'This set fell off the refrigerator a couple of weeks ago and cracked the
cabinet, but it didn't hurt the radio a bit. It never stopped playing. However,
yesterday it suddenly quit. While you're at it, you may as well get a new cabinet.'
"We both know it was not coincidence that the tube failed shortly after the
radio took a tumble. Even though the shock was cushioned by the tube's being in
a socket, the jar was still sufficient to fracture or weaken the filament. It
was only necessary to turn the set on and off a few times and expansion and contraction of the filament
did the rest. You'll recall that when we replace a tube in such a set we always
warn the customer other tube failures may show up soon as a delayed result of the
radio's being dropped. If we're wrong, the customer is glad; if we're right, he
has been prepared."
"You're the boss," Barney shrugged as he tossed the tube into
the trash barrel and got a new one from stock. "About now would be a good time for
us to have a little heart-to-heart on the general subject of pulling tubes," Mac
remarked as he leaned back against the edge of the bench. "You've displayed some
distressing symptoms of becoming a bulb-snatcher lately."
"Who, me ?" Barney exclaimed.
"I don't go swiping light bulbs around here."
"I'm not talking about light bulbs; I'm talking about tubes," Mac explained. "As in everything else, there is one
right way and about a dozen wrong ways of performing this simple, basic, service
operation. A technician who deserves to be called such does it the right way. An
untrained person who regards the tube as a 'bulb' because it lights up does it the
wrong way. He isn't a tube puller; he's a bulb snatcher because he doesn't know
any better. He doesn't appreciate the intricate, fragile nature of a tube nor its
easily damaged socket. There is no such excuse for you."
"So what am I doing that's wrong ?"
"Let's take what just happened. You had no
business trying to pull that hot tube with your bare hand. It was too hot for you
to hold on to it securely. That's why it flew out of your fingers. You were just
too lazy to reach up for the tube-puller sitting within easy reach. Had you done
so, you would not have burned your fingers, and the shop would not be out the cost
of a new tube. How many times do I have to thump it into your pumpkin head that
I want you always to use a tube-puller ? Not only does it protect you against burns,
but it also protects you from the ever - present possibility of having a tube break
in your fingers and seriously injuring one of your most important servicing tools:
your hand."
"OK; from now on I'll use your darned old tube-puller. Now are you
happy ?"
"No, because I don't believe you. You'll get in a hurry again and do the
same thing over. But even when you do use the tube -puller you still manage to goof.
You wrestle that tube around and around like a dentist trying to extract a stubborn
molar. Remember there's one basic difference between you and the dentist: he doesn't
have to put back what he is taking out of the socket; you do. If you yank the tube
this way and that to get it out, the pins are not only bent out of shape but the
socket itself takes a terrific beating."
"But look, Boss: some of those tubes are
darned hard to get out. You don't just lift them out with your thumb and little
pinkie like plucking an olive out of a big jar."
"Granted; but you still don't have
to pry them sideways so far the pins are bent. Rock them back and forth through
a small arc, first one way and then the other; but don't push them over until the
pins are clearing the socket holes on one side and are being bent at a forty -five
degree angle with the tube base on the other. That's a dandy way to crack the envelope
of miniature tubes. Even if that doesn't happen, you spread the jaws of the tube
socket receptacles so far apart they can't grip the tube pins when the tube is replaced.
If you will only use the tube puller so you can get a really good purchase on the
tube, you can lift it nearly vertically out of the socket with the aid of just a
little rocking."
"How about loctals ?" Barney asked with a look of low cunning.
"Now you bring up one of my pet peeves. I have never liked loctal sockets because
the tube must be pushed sideways to break the lock. The strain this puts on the
socket negates any advantage of holding the tube firm mechanically - at least in
my book. You know that time after time we get a radio in here with loctal tubes
in which every socket is making poor contact with the pins. Wiggling a tube slightly
with the finger will produce excessive noise or actually make the set cut in and
out. This is the rule, not the exception, with loctal tube receivers."
"Yeah," Barney
agreed; "and don't forget that sinking feeling a technician has when a stubborn loctal tube finally does break loose and comes up with some of the guts of a broken
socket still clinging to the pins!"
"Give the devil his due, though," Mac suggested.
" Loctal and octal sockets have one big advantage: they certainly make it easy
to replace a tube in a hidden socket."
"You can say that again. I don't know of
anything more maddening than having to fumble around like a coon fishing in a crawdad
hole trying to replace a miniature tube in a blind socket."
"There are a few things
that help there, too. You've doubtless noted that some of the service literature
actually shows the pin positions of the sockets. Half the battle is knowing you're
holding the tube in the right position for the pins to slip into place when you
do get lucky. If this information isn't in the service literature, it's very helpful
to observe carefully the way the blank position is pointing when the tube is removed
from the socket. Don't trust your memory. Make a little diagram. It can save you
minutes."
"Another thing," Barney added, "is that a pin straightener is worth its
weight in gold in a deal like that. If one of the pins is bent out of line, you
can turn that tube around and around until the pin wears a groove in the top of
the socket without it's ever dropping into place."
"That's my boy!" Mac applauded.
"The fact is that using a pin straightener on every miniature tube before putting
it back in the socket is double insurance against socket damage and loss of time."
"Seems to me we're running into quite a bit of socket trouble lately," Barney commented.
"You're right and I don't think it's sheer coincidence. I give lots of credit to
the do-it-yourself tube checkers found in drug stores and other places these days.
These encourage radio and TV set owners to pull the tubes out of their receivers,
check them, and then try to put them back where they belong. Bulb- snatching runs
riot. The end result? A lot of mangled sockets!"
"We're getting pretty clever at
repairing those messed -up tube sockets, though," Barney observed.
"That we are.
With patience, a good eye, and a steady hand, you can use a very sharp-pointed scratchawl and work down through the tops of many sockets and carefully pry the
spread jaws of the pin receptacles back together so that they again grip, instead
of merely touch, the tube pins. With other sockets, especially some types of wafer
miniatures, you have to work from the bottom of the socket. You need very sharp-pointed needle-nose pliers. I find a pair of surgical clamps is ideal for the
purpose. With these you can go quickly around a socket pinching the spread jaws
back together. It is often amazing how much difference this simple operation will
make in reception in a radio or TV set in which the tubes have been making a sloppy
contact with the socket."
"Mac," Barney said hesitantly, "I want you to know I really
intend to remember what you've said about tube - snatching. It makes sense. And
anything I do as often as I do taking tubes out of sockets and putting them back
I want to do right."
"I know you mean it, Barney," Mac said gruffly; "and I like
your saying you want to do right anything you do often. I've often remarked I can
tell if a fellow is really a technician or not by watching how he does three things:
take a tube out of a socket and put it back, solder a joint, and adjust an alignment
trimmer. Keep that in mind and do likewise."
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.
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