[mikehorning]

Well, I went looking for either a case for my model 70 chassis or a chassis for my 18b case and wound up finding someone not too far from me who was selling a complete model 70 for a good price. I think I'm going to work on this first while I continue to look for an original chassis for my 18b.

I also had a question. I am new to radio restoration, and I think from reading comments on the phorum that the first thing I should do is probably replace the caps. I was comparing this chassis (pic attached) with my other model 70 chassis, and I noticed that one of the Bakelite capacitors is different. According to the specs sheets I have, the model 70 should have a Bakelite capacitor with number 3903-J installed. The chassis currently in my 18B does have this, but the Model 70 that I just bought has a 3903-L (see picture with the arrow). This block also has what looks like a capacitor soldered onto the outside of it.

Has anyone seen this before? Everything else on the in the chassis seems to match up with the early Model 70 receivers.

Note from site admin: Sorry, but the photos which were attached to this post are no longer available.

[rghines1]

Hi Mike,

That's a nice old radio you have there. It's a hard radio for most beginners to tackle. Take your time and visit philcorepairbench.com on how to rebuild the bakelite blocks. The cap on the side of the bakelite block is likely a vintage repair. Common sight on radios of this vintage.

Richard

[Uffda]

Sounds like you did good Mike. That is an exceptionally clean chassis.

[mikehorning]

Thanks Phil, I actually cleaned it up a little before taking the pics, but it does appear to be in really nice shape. The woman that sold it said it belonged to her father, and he had had it for years with the intention of fixing it up. It seems to be pretty original.

Richard, thanks for the information. I will definitely be taking my time with this. My brother has a background in electronics, and he is helping me out along the way, but I am always grateful for the input from here. Neither one of us has restored a radio before. Right now, I've been reading up on them before I jump into anything too serious.

[gary rabbitt]

Nice set Mike,
The chassis does look clean, and those copper (Mershon ?) capacitors are still present. Also the gloobe style tubes are a plus.
You have the right idea on going slow but deliberate. No hurry in a set like this.
Take care,
Gary.

[mikehorning]

I thought I would post a few pictures of my first restoration. I think it turned out pretty well thanks to all the help I received on the Phorum. For the cabinet restoration I went with Dark walnut on the outside and medium on the face. I think that was the way they originally looked, but I wasn't sure. Either way, I liked the look in the end.

I also wanted to get some advice on the escutcheon. I think this one is made out of brass, at least it looks like brass under the paint. You can see that there is some missing in the picture. I wondered what you guys did with them. Are they normally shined up, or did they originally have some sort of paint on them? I may just leave this one as is.

Note from site admin: Sorry, but the photos which were attached to this post are no longer available.

[49Stude63]

Mike on the cap your arrow is pointing to it appear that bakelite block shorted or is dead, some of those bakelite blocks were 2 and 3 part depending on the part number. On my model 16X console they clipped the old dead cap out and did the same just put a new cap in the circuit. If you get the service data for it and it doesn't show that cap as an update then when you rebuild the bakelite blocks you should not need that cap. Ron may comment but to me it appears to be a later repair of the radio to replace one of the dead sections of the bakelite block. Se if the cap now installed and one of the sections of the bakelite block, or if it is a single section does it match. Nice looking and should be a an easy restore since what you have to start with is in great condtion.

[mikehorning]

49stude,

You were right about that. I actually forgot to mention that I restored the chassis too. That block had the original capacitor clipped out and was replaced with the one on the outside. After replacing the capacitors, a coil, the power cord, and the speaker wiring, it sounds like new.

[49Stude63]

There are always debates on the correct color and correct gloss level of these old radios but the problem with lacquer is that it is an open coating which is why water will seep though the lacquer and leave rings in the wood below. Most of the newer coatings like polyurethane and others when exposed to air the binders and resins actually cross link and seal the surface. That being said when the old radios and lacquer if they were exposed to cigarette smoke the nicotine would leach into the lacquer and give it a darker look and in those days the lacquer typically used nitrocellulose resin and it would naturally yellow out and get darker also. I think the color scheme you went with looks good, definitely a gigantic improvement over the original condition that you found it in. On my 640 that I just picked up with a chairside I will follow Ron's and Brian's 650 scheme and will post some pictures after it is restored.

[Arran]

I think that the sides (if you can call them that) came out way too dark, they may have been shaded but it was only slightly darker then the front panel. Unlike the mid thirties Philco tombstones these cathedrals actually used nice veneer on the sides so you don't really want to cover it up. Another thing to keep in mind, with future projects, is that the grain in all of these sets was filled so the pores of the wood wouldn't show, walnut and mahogany are open grained whereas poplar, maple, and beech were closed grain so the filler was used to keep the finish consistant. I used to redo sets without grain filling but even at the time I thought that it didn't look right, I have started to redo some of my past restoration work because of that and the fact that I used oil stain.
With regard to lacquer being porous, it really isn't, what happens is that lacquer is somewhat brittle and becomes more so as it cures, polyurethane is more flexible like rubber, alkyd varnish is somewhere inbetween. In the situation where lacquer is sprayed over wood, wood is like a hard sponge that expands and contracts across the grain with moisture and temperature, as it moves the surface of the lacquer develops cracks and holes allowing moisture in and out. It doesn't really matter what sort of finish is used the wood is still going to expand and contract across the grain, what makes the difference in keeping the moisture out is whether the finish can move with it. Notice the way old lacquer tends to craze and flake off, it's almost always across the grain, the more it crazes the more moisture can get in leading to still more expansion and contraction, heat or cold will also accelerate the process. One of the traditional treatments for wood on boats is something called marine varnish, it cures slowly and never really hardens completely, the result is that it seals the wood, does not crack, and keeps the moisture out.
Best Regards
Arran

[Texasrocker]

Congrats!!Very nice looking Mod 70 indeed! I cant imagine someone tacking-on a new replacement cap to a orig Philco bakelite cap block in the past!Shame-Shame!!

[49Stude63]

Arran in the microscopic sense Lacquer is porous simply the nitrocellulose lacquers form a layer by the solvents drying out and the lacquer organic chain structures laying like bricks on top of each other without any mortar. That is why you can use lacquer thinner and dissolve the lacquer even after it has been dried (for many years) that is one of the tricks of the trade to fix alligatoring of old lacquer when no major chips are missing, the lacquer re-flows itself. So any solvent to the least aggressive to the most aggresive will have an impact on lacquer. Since the early forms of lacquer were made with the combination of "gun cotton" (cellulose) and nitric-acid lacquer had some covalent bonding with N(nitrogen), C(Carbon) and O(oxygen) and since water (H2O) can also be classified as a solvent since it will exchange and react with lacquer, so will the outside air and any impurities like nicotine, cooking grease over time (that would be in most kitchens in the 30's-40's) and the lacquer when exposed to direct sunlight over the years the lacquer will photochemically react via IR and UV radiation to break the chemical bonds down also. So there are holes between the lacquer components , not holes visible to the naked eye but holes that are open to small molecular materials, like water, etc. Later coatings usually have a crosslinking function that takes place either by the addition of another chemical component or by the evaporation of the solvents that better seals the surface making it more resistant to the outside impurities.

[Arran]

Arran in the microscopic sense Lacquer is porous simply the nitrocellulose lacquers form a layer by the solvents drying out and the lacquer organic chain structures laying like bricks on top of each other without any mortar. That is why you can use lacquer thinner and dissolve the lacquer even after it has been dried (for many years) that is one of the tricks of the trade to fix alligatoring of old lacquer when no major chips are missing, the lacquer re-flows itself. So any solvent to the least aggressive to the most aggresive will have an impact on lacquer. Since the early forms of lacquer were made with the combination of "gun cotton" (cellulose) and nitric-acid lacquer had some covalent bonding with N(nitrogen), C(Carbon) and O(oxygen) and since water (H2O) can also be classified as a solvent since it will exchange and react with lacquer, so will the outside air and any impurities like nicotine, cooking grease over time (that would be in most kitchens in the 30's-40's) and the lacquer when exposed to direct sunlight over the years the lacquer will photochemically react via IR and UV radiation to break the chemical bonds down also. So there are holes between the lacquer components , not holes visible to the naked eye but holes that are open to small molecular materials, like water, etc. Later coatings usually have a crosslinking function that takes place either by the addition of another chemical component or by the evaporation of the solvents that better seals the surface making it more resistant to the outside impurities.

Not disagreeing with that at all, but it does take considerably longer for water to get past a relatively fresh coat of lacquer verses an older crazed one, both are much more resistant then the old shellac finishes. I don't think that nitrocellulose lacquer is quite as volatile as gun cotton, at least after the solvents have evaporated out, the ingredients may be similar but I have taken off old lacquers with a heat gun and it never violently combusted as it's chemical cousin would have. From what I recall gun cotton was discovered after a cotton rag was accidentally dropped into nitric acid, washed out, dried, and then exposed to a flame. It's been a long time since I have taken chemistry, much of what I know on the subject of finishes was from direct experience.
Best Regards
Arran

[Texasrocker]

Very nice looking Philco 70!

[49Stude63]

"Quick-drying solvent-based lacquers that contain nitrocellulose, a resin obtained from the nitration of cotton and other cellulostic materials, were developed in the early 1920s, and extensively used in the automobile industry for 30 years" I think they call the material that is one stage of the chemical reaction "gun cotton" which is explosive but then this material if further reacted creates a lacquer polymer chain. This conversion was totally by accident and in this case that accident didn't go boom!!! If the water is present on the lacquer layer long enough it will seep though the laquer layer and the layer itself will start turning milky. Unlike latex paint that cross-links when it dries so that even if you put water back on dried latex paint if you let it sit a short time and mix it back up you will have water with dried latex paint still in it and not latex paint again. You can take a chunk of dried nitrocellulose laquer and add the solvents back to it and let it sit a short time and mix it and have lacquer again. That is why I called it an open layer since after a while, water, cooking oil vapor, nicotine will eventually over time be absorbed into the lacquer layer which is why most old radios have that dark look to them. Lacquer itself will yellow and darken but the crud it has absorbed over the years adds to this, mostly nicotine from smokers in the past. The newer lacquer resins from the later 40's to early 50's were a result of a safer way to make lacquer and reducing the chance that your paint plant goes boom if you make a minor error.

This link I found covers some of the history and drawbacks of each type of lacquer but all lacquers in the 30's and early 40's were nitrocellulose types. http://www.taunton.com/finewoodworking/M...px?id=2948