Collier & Beale Pacemaker 5155
Let's get back to the cabinet, but before we do, check this out. It's a Collier and Beale Pacemaker "Petite" from 1955, made in New Zealand.
Collier & Beale Pacemaker 5155
Here's another one. This photo was sent in by Robert Lozier. Website

Motorola 53R cabinet
The cabinet now gets a coat of white primer. That looks really good. Look how crisp the word "Motorola" came out.
Motorola 53R cabinet
Yes indeed! Very clean and crisp! It's ready for the paint. Wait a minute....
Motorola 53R cabinet
Mother of God!!
 I became apoplectic.
The radio cabinet feels like it's made out of sand paper! Now the paint has to come off again.  Oh well.

Here is what I think the problem is.
It's late August in Pennsylvania. It's chilly out in the morning, but the humidity is too high for spray paint.

Motorola 53R cabinet
Now it will sit on this shelf until the weather changes.

There are two Sam's Photofact Folder's for the 53R, and the pictures on them look like a before/after shot of this radio.
Click on either picture to download the Sam's Folder.

Motorola 53R chassis
Let's take a look at the radio chassis. The parts are mounted on a double-sided circuit board.
Motorola 53R chassis
The circuit board is called a PLAcir, short for "plated circuit." Later, we would call them "printed circuit" boards.
Motorola 53R chassis
Motorola 53R chassis
Notice the scorch marks around the tube "sockets" on the top-left. The circuit board is made of paper fibers in phenolic resin and tends to burn from the heat of the tubes, especially the 35W4 and 50C5 tubes.

Not everything made "back then" was made to last. This radio was made as cheaply as possible. It doesn't even have real tube sockets. With enough use, the 35W4 and 50C5 will burn the board under them to a crisp and it will begin to fall apart. In the right-hand photo, one of the copper traces has lifted off the board, and that part of the board doesn't even get hot.
   35W4      50C5     12BA6 12AT6     12BE6  

The 35W4 is the rectifier tube. The 50C5 is the audio output tube. They both run very hot, and the glass reaches a temperature of 428F. These two are what has scorched the circuit board.

All of the tubes tested "new" except the 50C5, which was at 87%. I tried to figure out how much this radio was used based on the 87%, but it's really not possible. First of all, you'd have to know exactly how long the tube would last. Let's say it's 2000 hours. You can't take 87% of 2000 because the decrease may not be linear. It might take 50 hours for the performance  to go down 10%, but another 500 hours to reduce another 10%. The 2000 hours tube life was just a guess, anyway. Eventually I gave up trying to figure it out.

Motorola 53R chassis
I started to add a real tube socket, but it elevated the tube and it interfered with the back of the radio. Of course, the tallest tube needs to go into the socket. To make it fit, a hole would have to be drilled through the circuit board to drop the socket into, and I'm not going to do that. Haha... I could also drill a hole in the back of the radio, so the tube sticks out.

I decided to replace the funny black thing with a yellow thing. It's a Sprague brand capacitor, sometimes called a "Bumblebee."
Reading the colors from the bottom-up, they are 4, 7, 000, 20%, 400, so the rating is 47000 picofarad +/- 20% at 400 volts.
Motorola 53R chassis
I ran into something very strange.
When the wire from the yellow thing was inserted, the little copper pad popped off the circuit board. That's OK, it doesn't seem to be connected to anything on this side, so the connection must be on the other side.
Wrong. When the board is held up to a strong light, you can see there is no connection on the other side, either.
This was never connected to ANYTHING!
Oddly enough, there was a blob of solder on the circuit board which served no purpose. Looking at the schematic, I saw the capacitor should have been connected there. I bent the lead over and soldered it.
This capacitor is connected across the AC line and isn't really needed for the radio to work. Those "Bumblebee" capacitors are notorious for bursting open. They're oil filled and are sealed in plastic. They work great in amplifiers, but placing one across the AC line probably wasn't a good idea. I wonder if Motorola, as a quick fix, omitted the solder connection during assembly.

The filter caps were replaced. (There were two in the metal can.)
Every time the soldering iron touched the circuit board, the copper lifted off. It was reinforced along the edge with solder.

It seems Motorola came out with the plated chassis the year before, in 1952. Read about it  here.

Motorola 53R speaker
Check out the speaker! See the round thing in the middle?
Motorola 53R speaker
Motorola put the speaker magnet and voice coil in FRONT of the speaker. (The silver and tan transformer isn't part of the speaker.)
This allowed Motorola to make thin radios. They even made a clock radio you could hang on your wall.

So what's the big deal? Somehow, the voice coil needs to work in reverse. Instead of pushing the paper cone from behind, it has to pull it forward. Otherwise, most of the sound would come out of the back of the radio.

Motorola pin-up clock radio advertisement
Here's the radio that hangs on the wall, thanks to the new speaker design. Model 52CW. Click on the picture to see the entire advertisement.
Note: it's impossible for the hour hand to be pointing directly at the 8 if the minute hand is showing twenty-some after the hour. Didn't they notice this?
Motorola pin-up clock radio
Here are actual Pin-Up Clock radios. Notice the time on the clocks is the same as on the advertisement.
Even though you could "pin it" up, you still had to find a place to plug it in. It is not battery powered.
Motorola pin-up clock radio
Motorola pin-up clock radio
How it's shown in the advertisement, and how big it would really look. Hahaha, they did this stuff all the time with these drawings.
Notice, there is no electrical cord in the original drawing. When you got it home and went to "pin" it up, there may have been a slight problem. It's twenty-two after seven (and six seconds), according to the clock. The sun is out. If it's summer it could be either AM or PM. Which do you think it is?

Enough about the speaker and the wall clock. Back to the 53R radio, the knobs are made of plastic and were easily polished up.
Now let's do some painting.