[wendell]

Hey Guys,

I am relatively new at this. I have repaired 4 radios, sort of basic early 50s table models, really without knowing very much about what I was doing. From reading forums like this one, I learned that the first thing you do is replace the caps..that's what I did on the first 4 radios and fortunately they all worked fine when I finished. I recently bought a model 87 at an estate sale. From the information I've found it was manufactured in the fall of 1929. The cabinet is in beautiful condition. It's missing 2 tubes which I'll address later on. I have not removed the chassis from the cabinet yet, but in looking into the radio from the back it looks radically different from anything I've seen. There are a couple of big metal enclosures that I can't identify. I guess my question is, are the caps similar to the caps in the later models, and is this project something that I should probably farm out to someone more knowledgeable and experienced? I really don't want to get into something over my head with this one. Any advice would be appreciated.

[Radioroslyn]

Hi and Welcome to the Phourm!
Well the Model 87 is a bit different from the '50's table radios. The good thing is electrically it's much simpler. It's a T tuned R radio F frequency set. Basically it amplifies the signal from the antenna through three amplifier stages (the first 3 #26 tubes). The #27 tube turns the amplified rf signal into audio. Next the #26 tube amplifies the audio signal to drive the two #45's in the audio output.
To service this old timer you will need to remove the filters caps and replace them. On this set they are in a metal can full of paper, aluminum foil, and tar. This will require you to remove the can, heat in an oven at 175deg for 20min or so till the tar is soft. Then pull all innards out. Replace with modern film caps. Note the small value like a 1 or 2 mfd. That's the worst of it. The rest is just the small paper caps.

Common problems open rf coils( can be rewound by hand easily) open audio driver transformer(replacement not hard to find). Be careful with the tubes mostly the 45's their expensive!

I had an 87 years ago back in the 70's
Good luck w/it
Terry

[wendell]

Thanks for the reply and the information. I think I'll pull the chassis and take a look.

Unfortunately, the two missing tubes that I mentioned? They're the 45s.

Wendell

[Radioroslyn]

I'm Surprised! not
Terry

[wendell]

Since my post yesterday, I have removed the chassis from the cabinet of my model 87.
I removed the bottom plate, and was surprised to find that the only component visable on the bottom side is one resistor. According to the schematic, there is a condenser block with 9 or 10 capacitors in it. There is a box on the underside about the size of an altoids can. which is soldered closed. Are the capacitors enclosed in this box? There are two black wires coming out of the box. There are no paper caps under the chassis. Any observations on this?

Thanks for any help,

Wendell

[Radioroslyn]

Looks like there is a bunch of them in with the filter condensers. That small metal box is probably the filament bypass caps for the 26 tubes. It would be connected across the hum pot. It's been a good while since I've been inside one.

I just got a model 20 console, going to go get it on Monday. It has a similar set up with the filters in a tar filled can. Once you figure out how everything is wired up inside it an easy job to get it back together, just messy.

I'll mention in passing that your 87 uses triode tubes for the rf amp. If you replace the 26 rf tube it will require the re adjustment of the neutralization trimmers. It's a bit of a pain so don't dittle with them.

Terry

[Arran]

The schematic for the model 87 can be found here, it even has a layout of that potted condenser can: http://www.philcoradio.com/tech/images/87.jpg
I'm not sure whether that can has a terminal strip or not, if it does then it will make life much easier. I really wish people would quit pinching the used #45 tubes out of these sets, someone at some point has to drill it into the heads of these stupid audiophools that amplifiers are based on science and not black magic and they are not going to get hi fidelity sound out of a set worn, used pair, of 70+ year old triodes. In any event you can find another used pair of #45s (likely st style) or substitute a pair of 1619s in their place with adapters.
Regards
Arran

[wendell]

Thanks Arran,

No, there's no terminal strip, everything is hardwired from point to point. This may be a blessing in disguise...I may just disconnect the filter block from the bottom and connect the new caps to the original wiring under the chassis. Thanks for the info about the 1619 tubes. What kind of adapters are you talking about? I'm very new at this..

Wendell

[Radioroslyn]

http://www.dialcover.com/tubes.html
Scroll down a bit to find the 45 replacements.
Terry

[Ron Ramirez]

I may just disconnect the filter block from the bottom and connect the new caps to the original wiring under the chassis.

Don't do that, there isn't enough room under the chassis. Plus, such a job will be very sloppy.

The filter condenser can has a set of terminals built-in, on the bottom. The bottom piece of metal, which contains the terminals, can be easily removed from the rest of the can - you do have to remove the can from the radio first.

If you remove the can, take lots of pictures and notes so you know how everything hooks up before you remove it!

Now, with the can removed, remove the bottom piece as I mentioned; it easily pries off revealing several wires connected internally. Cut these wires and set the bottom piece aside.

You must now remove the innards of that can, which is sealed in tar. A small torch will melt that stuff out, but it is very messy and is a job that must be done outdoors.

With an empty can, once it cools off, you may want to give it a fresh coat of black paint as the heat from the torch will ruin any remaining old paint on it.

Go to my website, and look at the 87 diagram:
http://www.philcoradio.com/tech/images/87.jpg

At the top right of this image is a diagram showing how the capacitors hook up on that terminal board that is the bottom of the filter block can. Notice In included positive signs in case you use electrolytics, but many guys prefer using metalized film capacitors here - they are larger physically, but should last longer.

Imagine this diagram in mirror image, as this is how you will have to connect the capacitors - they should go on the side of the terminal board that will be inside the can when you are finished.

This involves some work, but will result in a much neater installation.

[wendell]

Ron,

Thanks for the reply. Good information. I don't mind doing it the harder way, and i agree that it would be a much neater job putting the new caps back into the original can. As I have mentioned, I'm new at this and not very knowledgeable about schematics yet, learning as I go, but I'm having trouble understanding the schematic of the condenser block diagram on your site. Do the numbers on the block diagram correspond to the numbered connections listed on the main schematic?

Wendell

[Ron Ramirez]

Yes, the numbers on the block diagram correspond to the numbers on the schematic.

[Arran]

Thanks Arran,

No, there's no terminal strip, everything is hardwired from point to point. This may be a blessing in disguise...I may just disconnect the filter block from the bottom and connect the new caps to the original wiring under the chassis. Thanks for the info about the 1619 tubes. What kind of adapters are you talking about? I'm very new at this..

Wendell

I meant that the bottom of the condenser can may have a terminal strip built in, the one in my Philco 96 has that along with a few bakelite condensers.
Regards
Arran

[Texasrocker]

You can also remove the tar old with a Wagner type electric heat gun and holding the caps can metal enclosure with a big pair of pliers wearing cotton gloves. Hold it upside down and move heat around metal enclosure. It may take a few minutes, but the tar will let go and you can pull the old caps out with other pliers. I usually do this procedure over a old cardboard box to catch the hot dripping tar. I have rebuilt several old late 20s era RCA Radiolas and Atwater Kents orig cap banks using this method. No need to mess up a kitchen oven ( smells) or use torch flames at all. The heat gun will melt the old tar with patience. Do this process in a well ventilated area if you must, and don't consume any fumes. Personally, I draw out a new schematic replicating the orig and use new terminal strips to mount all the same caps under chassis in place of the orig cans when possible. Takes up less space also, but then again, some folks prefer restuffing old cap cans for originality reasons or space constraints in some chassis'. Most TRF type radio chassis have mucho spare room underneath. Just my .02

[codefox1]

The 1619 is an octal based tube with approximately the same filament voltage requirements but a bit more current. You will need to connect the G2 to the plate, and otherwise connect the remaining elements (G1, Cathode, Plate, and filaments) as shown in the tube manual. You will then have an ersatz 45 output triode circuit.

You can accomplish this by replacing the tube socket on the radio with octal types, or making adaptors with a male 4 pin and octal female sockets (Make sure you have enough height in the cabinet!.) Perhaps a less than stellar set or 45's might be obtainable a a reasonable price if you are not in a rush, and do not want to customise this set. I would think you could get a pair of just OK 45's for maybe $25, and they would probably last a very long time in an ordinary radio in good condition.

Pinouts for the tubes are available at Nostalgia Air and other places if you want to go on, and duds and sockets are not hard to find to build adaptors. 1619's are cheap, but not as plentiful as they once were. Again, patience is your friend.

Of course there are dozens of other options, all of them reversable, to get a set that otherwise works OK to go the final mile and play through the speaker whilst you are waiting for the right parts.