Mac's Service Shop: Chemicals for the Service Shop
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Liquid Wrench, of which I have a can sitting in my garage, has been around since 1941 per the company website. WD−40, of which I also have a can, first appeared in 1958. That is surprising to me since I was using WD−40 long before having heard of Liquid Wrench. Mac introduces side-kick technician Barney to Liquid Wrench in this episode entitled, "Chemicals for the Service Shop." It appeared in the September 1965 issue of Electronics World magazine when both products had been widely available for quite a while. Strange that WD−40 was not mentioned, too. Also discussed in the technodrama™ are liquid protective coatings like spray-on insulation and electrical connection weatherproofing coatings, cleaners (as replacements for the dreaded carbon tetrachloride, aka "carbon tet"), adhesives, lubricants, and some products like component cooling sprays and paints/stains for repairing cabinets. Mac's Service Shop: Chemicals for the Service Shop
Barney marched into the service department and ostentatiously placed a small spouted metal can on the shelf holding the various chemical service aids used in radio and TV servicing. "Please note," he said to Mac, his employer, "my free-will offering of one can of Liquid Wrench." "What's Liquid Wrench and why the sudden burst of generosity?" "You might say Liquid. Wrench is a second-generation penetrating oil. I discovered what it could do Sunday when I took down my ham transmitting antenna to replace the feed-line. Bolts holding the wire in the terminals were so badly rusted and corroded I couldn't budge them. The friend helping me suggested penetrating oil, but I didn't think much of the idea. My limited experience with penetrating oil led me to believe you had to let it soak in for two or three hours before it did much good; and I needed that antenna back up right away to keep a schedule. But my friend got his can of Liquid Wrench and squirted it on the bolts and nuts. In two or three minutes we were able to unscrew the nuts. I don't mean we could turn them with our fingers, but they all came off with a little persuading. "Right then I decided I wanted a can of this quick-acting penetrating oil in my hip pocket the next time I climb a tower to replace an old TV feedline or to loosen the rust-encrusted nuts of an antenna rotor. By golly, there's progress in everything these days - even in penetrating oil!" "It's odd you should discover this right now," Mac said. "I decided the same thing a couple of weeks ago and filled out an order to update our 'liquid tools,' as you might call them. I was arranging these on the shelf just before you came in, but a modern penetrating oil is one thing I overlooked. "A technician is prone to think only of hand tools and service instruments as service aids and forget all about the wide variety of chemicals that can make his work so much easier. The day when all the chemicals a service shop used were a tube of speaker cement and a bottle of carbon tetrachloride is long gone. What say I sort of go through the items on this shelf with a little refresher discussion of the uses - and abuses - of each?" "To coin a phrase, 'You're the boss,''' Barney quipped as he perched himself comfortably on a stool and prepared to listen. "Let's start in the 'Protective Coatings' section with this bottle of liquid tape. In modern compact radios, tuners, tape recorders, and TV sets, wrapping an exposed wire with tape to provide insulation is often as difficult as trying to splint the leg of a mosquito inside a safety match box. Instead, you simply brush on a coating of the contents of this bottle. It quickly dries into a crack-proof, high-voltage layer of insulation. You can also brush it on the handles of tools to insulate them. This bottle of red insulating varnish will do the same job for solder connections, and it also serves nicely for sealing adjusting screws. Of course, we can call on our old reliable corona dope for really tough arcing cases in the high-voltage circuit. Finally, here is a bottle of silicone resin coating with the trade name of Print Kate to restore the protective coating to printed circuits after a circuit repair has been made." "That darned coating is a big fat nuisance when you're trying to solder a break in a printed circuit," Barney offered. "Not if you use this Print Kate Solvent especially designed to remove the silicone resin," Mac said, moving over to the next section he had designated "Solvents" with the shop label-maker. "And incidentally, here is some special low-melting-point solder especially designed to resolder a break in a printed circuit without the necessity for too much damaging heat. Your Liquid Wrench goes in this section as does this bottle of acetone for dissolving speaker cement. Always remember, a little of this goes a long way." "Yeah, I know," Barney answered. "The idea with acetone is to apply a little sparingly to a speaker-cone dust cover and then wait a few seconds for it to soak in. After that the cover can be lifted off intact with tweezers and can be used again. Trying to hurry things up by dousing the center of the cone with acetone is a good way to separate the voice coil from the cone." "Right," Mac approved, "and the same thing goes when realigning a warped voice coil. After the speaker shims are in place, the idea is to apply just enough acetone with a long curved eyedropper to the pleated voice-coil spider to soften it and allow it to take a new set with the voice coil properly aligned. Too much acetone may loosen the spider from its plate or, still worse, may carry softened cement down into the space between the voice coil and the pole piece. If this occurs, you've had it." "Hey, I'm surprised, knowing how you feel about the stuff, to see a bottle of carbon tet on the shelf under 'Cleaners.' " "Well, I still consider it deadly dangerous and know that breathing the fumes can produce serious liver damage; but I'm also a great one for 'going by the book,' and the fact remains that several tape-recorder manufacturers still specify carbon tet for cleaning tape heads, capstans, and even pressure rollers. Others warn against using the stuff on tape heads or any rubber parts. I suppose it depends on the material in which tape-head laminations are embedded and the chemical nature of the rubber used. At any rate, here is a bottle of tape-head cleaner for general cleaning of that area, a bottle of alcohol for use where it is specified, and this carbon tet to be used when called for. But when you use this last be sure you have plenty of ventilation so you don't breathe the fumes, and be careful not to splash any into your eyes or into any breaks in the skin." "Don't worry. I'm just as scared of that stuff as you are. I see you have a new pressure can of contact cleaner and another of glass-and-plastic cleaner. You know, it amuses me to see an inexperienced technician hopefully squirting contact cleaner on the outside of a volume-control shaft. In a very few cases this may clear up the trouble for a few days, but for lasting improvement the cleaner must reach the sliding contacts inside the control. I use the auxiliary flexible extension tube to squirt the cleaner through an opening where a terminal enters the control case. It will fog through here and saturate the whole inside of the control-including the two critical sliding contacts I mentioned. Unlike old carbon tet, modern contact cleaners contain a lubricant and an anti-corrosion coating in addition to the corrosion solvent; so their effect lasts much longer. "I'm glad to see that cleaner for glass and plastic. Lots of radios have plastic dial covers, and of course, most TV tubes now have bonded faceplate shields. Many cleaners for glass will attack and fog plastic - as you well know. It's a comfort to have one cleaner that can be safely used on both." "Okay, let's go on to 'Cements and Glues,' " Mac said. "Here, of course, is a tube of our old reliable speaker cement that does many more things than repair cracks in speaker cones. Fixing dial cord knots, securing the pointer on the cord, and fastening loose loop and coil windings are a bare beginning or the uses for this versatile clear cement. But it's not so hot for repairing broken cabinets, although many try to use it for that. This plastic cement or this Bakelite cement should be used to repair cabinets or knobs in accordance with the material of the broken item. Properly used, either will create a strong, durable, inconspicuous repair. Since not all cabinets are Bakelite or plastic - yet - this wood glue still comes in handy quite often. And this rubber-to-metal cement is excellent for fastening loosened rubber drives back on their shafts or wheels. Finally, these two tubes contain an epoxy cement and catalyst that combine into a glue coming as near to bonding 'anything to anything' as you will find. We don't need it often in service work, but it's sort of a reserve heavy artillery that can be called in when nothing else will do a heavy-duty cementing job. "Under 'Lubricants' we have a light machine oil for general lubrication, tuner lube for TV tuners, Lubriplate for sliding dial pointers and for tape-recorder and record-changer mechanisms, a fiber grease that will cling to a rotating gear or wheel in spite of high temperatures, and this silicone grease for providing a good heat-transferring bond for mounting power transistors." "That leaves only the 'Miscellaneous' section," Barney noted. "Yes, and there aren't too many items here. Of course, this cabinet repair kit embraces several individual stains, varnishes, shellac sticks, etc., with which we can work a scratch out of just about any kind of wood or plastic cabinet. Another item we both like is this pressurized can of refrigerant gas that is marketed under various trade names such as Circuit Kooler, Zero Mist, and so on. A shot of this gas will abruptly drop the temperature of a suspected item in an intermittent set and often make that component reveal itself as the cause of the trouble. We don't hold our fingers in the spray and freeze them, though, as the salesman told us one of his customers did!" "Practically all chemicals can do physical damage if used carelessly, I reckon," Barney observed. "But all you have to do is read the instructions and warnings on the can and then follow them. If they say: 'Don't use near an open flame'; or 'Don't inhale fumes'; or 'Keep away from eyes'; or 'Avoid prolonged contact with skin'; or 'Highly flammable,' assume there's a good sound reason for the warning and heed it." "See that you do," Mac said. "At any rate, that winds up our little seminar on chemicals. Keep your eyes open for additions to this shelf, though; I'm sure there are others that belong there." "Will do," Barney answered, getting off his stool and stretching, "but if you will allow me to coin another phrase - I'm full of 'em today - I think you should entitle your lecture 'Better Things for Better Servicing Through Chemistry!' "
Posted October 6, 2022 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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The wide variety of liquid service aids
available today are as valuable to the technicians as conventional tools.