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Author Topic: Wax For Sealing Oscillator Coils and Electrical Windings Will Kutler Phenomenal Film Handler Posts: 1506 From: Tucson, AZ, USA Registered: Feb 2001 posted 08-29-2006 10:29 AM                     I am putting this topic in the Film-Handlers for reference to anyoneone using antique amps/sound systems in their theatres that might require service. Brad can move thread to Film-Yak if he so chooses. Phil Hill or Mark G. would probably know the answer to my question. I am restoring some antique sound-system equipment that does use oscillator coils. The equipment is circa 1938. Wax was used to seal the windings on the Oscillator Coils as well as the IF Transformers. Over time the wax became an ooey-gooey dirty mess and requires replacement. . I thought that Q-Dope would have been a good alternative replacement for the coils, but I may have been wrong in my assessment? Maybe Mark or Phil can give us insight into the proper use and application of Q-Dope? So, does Phil or Mark know what kind of waxes were originally used for sealing windings and where to purchase?? Was it all just Beeswax, or were there "additives" to it??? Cheers Kutler  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 08-29-2006 03:49 PM                  Will, I think the original coil wax was a combination of materials commonly referred to as "Mineral Wax". It had a higher melting temp than that of pure beeswax. Perhaps Mark, or others, can add more info. Maybe Google would help you find a satisfactory replacement. (That's all I know about it)  |  IP: Logged Robert Minichino Master Film Handler Posts: 350 From: Haskell, NJ, USA Registered: Dec 2005 posted 08-29-2006 07:12 PM                        I don't know what was used on the coils of that vintage, but I know some of the newer stuff was sealed with paraffin (which is a mineral wax).  |  IP: Logged Ron Yost Master Film Handler Posts: 344 From: Paso Robles, CA Registered: Aug 2003 posted 08-29-2006 08:30 PM                     Found via Google: Zophar Mills Waxes I didn't investigate the site enough to see if one could order just a little bit, tho. Who knew there were sooooo many potting waxes? Not me, that's for sure! Hope it helps ya! Ron Yost  |  IP: Logged Jeff Stricker Master Film Handler Posts: 481 From: Calumet, Mi USA Registered: Nov 1999 posted 08-30-2006 06:26 AM                     Will, could be plain old beeswax. We were using beeswax to anchor the windings on auto radio tuning coils through the early 1980's. Worked well and held up in under-dash environment. Good luck with your project. Jeff  |  IP: Logged Ron Yost Master Film Handler Posts: 344 From: Paso Robles, CA Registered: Aug 2003 posted 08-30-2006 01:13 PM                     I think you're right, Jeff. I remember sticking my fingernail into the wax coating on old electronic parts back in the 50's-60's and my nail always went right in. Obviously beeswax. It was easy to scrape the stuff off, too. I messed with a lot of old radios and such back then where the wax had melted on some wax caps and such, if they were in a warm area of the chassis .. beneath a warm transformer or hot tube, for example. So I don't think they used anything very exotic for consumer stuff. Remarkable stuff, beeswax. Ron Yost  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-30-2006 01:42 PM                     I only use pure beeswax for this purpose. There are alot less contaminents in it that might affect the coil alignment you just got finished doing. Really, unless you're goimng to plan on moving this radio around then no sealent is the best sealent. Mark  |  IP: Logged Will Kutler Phenomenal Film Handler Posts: 1506 From: Tucson, AZ, USA Registered: Feb 2001 posted 08-31-2006 01:36 AM                     On my radio there are three sheetmetal grids that are "stacked" with enough room between them for the coils and various mica caps. Running down the center of this assembly is the band selector switch...actually several wafer switches. Anyhow, the who assembly was just encased in dirt, dust, etc, etc and the coil wax was a oooey-gooey mess that required cleanup...mostly to access the surronding parts that also required service. Anyhow, from all I read I though Q-Dope would be an excellent alternative to wax. Was I wrong on this one! Either I am just applying the Q-Dope wrong or it is just not compatable with a coil that was originally wax sealed. Due to the Q-Dope I am now concerned that I may have damaged 2 coils. Cheers Kutler  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-31-2006 07:12 AM                     Q-Dope is ok stuff but not consistant with being used on an antique radio if you want to keep it an antique radio. Cleaning old radio and TV's is a difficult matter at best and extremely time consumming to say the least. The liberal use of Q-Tips and the like is mandatory. If the original sealing wax cleans off then pure beeswax should be used to re-seal anything that needs to be. Use of a Caig Labs De-Oxide cleaners to clean the wafer switch contacts works extremely well, just fon't get alot on the wafers. When I overhaul a TV tuner thats filthy I remove it from the set and clean it in my ultrasonic cleaner, then I spray De-Oxide cleaner just on the contacts. The first photo is showing the oscillator wafer at the front of the tuner. The second is of the same wafer after the whole tuner was disassembled and ultrasonically cleaned. 1 ounce of Dawn Dish detergent was used in the cleaner! Mark  |  IP: Logged Will Kutler Phenomenal Film Handler Posts: 1506 From: Tucson, AZ, USA Registered: Feb 2001 posted 08-31-2006 02:34 PM                     Hi Mark Could not agree more with your last post. I gently used a heat gun and LOTS of Q-Tips to clean the coils. Also lots of Caig Labs deoxide cleaners. Sometimes the chemical cleaners will not dissolve all the oxides that can be built up on wafer switch contacts. In this case the old model railroaders trick can be used: Cleaning the contacts with a soft rubber pencil eraser....this does wonders! My original purpose for using Q-Dope instead of wax was for long-term preservation. I also thought that Q-Dope would be an easier solution to occasional preventative maintenance cleaning. My analysis turned out to be incorrect. I am not sure if I incorrectly used the Q-Dope or if it is just not compatable with the old resudial wax that was not removed during prep-cleaning. In any case it was not adhering to the windings or coil forms. As it cured overnight it would shrink and badly craze. It would also turn an opaque-milky white which I believe was the sign of non-adherence. Furthermore, the Q-Dope would crack and flake off quite easily. My problem is with two of my "A" band coils. These are two of the three with VERY fine windings...like in IF transformers. The microscopic winding wire is actually stranded...and those individual strands are BARELY visable. Looks like the wire was cotton covered and them sealed with the red varnish/lacquer/enamel or whatever it is?? Anyhow, as the Q-Dope peeled off I found that it had dissolved the red coating...revealing the underlaying cotton. Of course only the exterior layers of the windings are visible. While it does not look like the winding wires are broken, I am concerned about the effects of the compromised insulation! As Mark and others have said, the wax is VERY soft. A few weeks ago I took some of the parts home to Tucson with me for a stop at a local electronics supply store. My Ranchero does not have AC and the summer heat was enough to melt not only the coil wax, but also the IF transformer coil winding wax. Cheers Kutler  |  IP: Logged Ron Yost Master Film Handler Posts: 344 From: Paso Robles, CA Registered: Aug 2003 posted 08-31-2006 09:39 PM                     As Mark says, use pure beeswax. Some of the 'beeswax' sold in hardware stores is adulterated with parafin (so it can be sold at a lower price), so be careful what you buy. Pure beeswax isn't inexpensive these days, but it's worth it. Maybe you can find (or know) a local beekeeper? They'd most likely make filtered cakes of it, as there's a LOT of it after it and the honey are separated. Grandpa (well, -ma, actually) used to use biscuit tins to mold the small cakes in. They sold the cakes for ten-cents! It's a tad more expensive, now. I helped my grandpa some with his hives .. the separator was the most fun, for a kid. I do woodworking as one of my hobbies, and it's the bees-knees for lightly lubricating wood-screw threads, too. As I said, remarkable stuff. Ron Yost  |  IP: Logged Will Kutler Phenomenal Film Handler Posts: 1506 From: Tucson, AZ, USA Registered: Feb 2001 posted 08-31-2006 10:22 PM                     So, I'll clean up what I can and replace with beeswax. There are some local bee supply stores, so I should be able to get some. I was unsure if it was originally beeswax that was used, paprafin or a "special blend" So, I'll go with beeswax. Ron, I am also a woodworker. Good to hear someone elese familiar with the beeswax on screw trick. But a much cheaper solution...a bar or liquid Dial handsoap does the same thing Another old woodworkers trick. If one is using nails, take your hammer and nail and flatten the tip. Do this by putting the nail on concrete or hard surface and moderately hit the nail on the head as if your trying to nail that hard surface. The purpose of this??? It'll prevent your wood from splitting as your nailing it. And Mark...in the pic you posted it looks as if there is a white "dogbone" resistor. If those go bad what do you replace with? A 1 watt flameproof, wirewound???? Cheers Kutler  |  IP: Logged Jeff Stricker Master Film Handler Posts: 481 From: Calumet, Mi USA Registered: Nov 1999 posted 09-01-2006 06:14 AM                     Will, That looks like a dogbone capacitor in Mark's picture. Normally these are of low value (few pf) and are of the temperature compensating variety used in oscillator circuits to reduce drift over temperature. They are usually of negative temperature coefficient (meaning as temperature goes up, the cap value goes down). The coil in the circuit will have a PTC characteristic (increasing L with temp). The idea is to keep the C X L product constant over temperaturem which keeps the oscillator drift nearly zero. (easier said than done! I've spent may a day and night at this using temperature chamber -- but, that was in another life. ) Mark: excellent contact cleaning 73, Jeff  |  IP: Logged Will Kutler Phenomenal Film Handler Posts: 1506 From: Tucson, AZ, USA Registered: Feb 2001 posted 09-01-2006 04:15 PM                     Hi Jeff My RCA 816K has some dogbone style resistors. Not sure wat is special about them...if they were wirewound or what. Interestingly, the RCA parts sheet also specifries "insulated resistors". Not sure what that means and no one whom I have asked seems to know either. Yes, I am familiar with the temp compensating caps you have mentioned. Temp compensating caps were used on this radio. Unfortunately the specific caps and values are not specified on the parts sheet...just the OEM RCA part number...a ploy to force the consumer to purchase RCA parts. And the caps installed in my radio do not have the dot matrix code used to identify cap values/styles. What is printed on the caps are letter-number codes like M250 that no one seems to be able to decode...nor have I found any on-line info. Regards Kutler  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-01-2006 04:42 PM                     The dogbone resistors are usually wirewound and tighter tolerance. The tuner I posted above fomr my RCA 721TS has no AFC at all but once it warms up for 5 min. it is completely stable. Mark  |  IP: Logged

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