Here is a before and after picture of my vintage RCA Victor 15X Radio. I think you'll agree that the makeover was a complete success!
About my RCA Victor 15X Radio
I paid $10 plus shipping for this radio at on online auction. I don't think any other "vintage radio enthusiast" wanted to touch it because:
1. There was physical damage to the Bakelite cabinet:
2. The tone switch knob was missing. Most collectors know how hard it is to find matching knobs.
3. The dial indicator, circular and unique to this radio, was missing.
4. The dial cord was either broken or missing.
5. The back panel was missing, exposing the built in antenna.
"Old Time Radios! Restoration and Repair" book on Amazon
I consult this book often during radio restoration. I grew up in the transistor and rectifier era and this book taught me a lot about vacuum tube and selium rectifier technology.
Step 1 Remove Chassis from Cabinet
The RCA Victor 15X uses only two screws to hold the chassis in the cabinet. One on each side of the chassis. The Volume, Tone, and Tuning knobs must be removed first. They just pull off. As mentioned, my RCA Victor 15X is missing the Tone switch knob. Once the screws are removed, the chassis slides straight out of the back of the cabinet.
The Tuning Dial Window is also held in place by two screws, one on each side. You can remove the Tuning Dial Window from the back once the screws are removed. Handle the Tuning Dial Window with care as it is made of glass. I removed the Tuning Dial Window both to clean it and to prep the cabinet for paint.
Step 2 Chassis Cleaning and Lubrication
I use compressed air to remove any loose dirt, then Windex moistened paper towels to remove any remaining dirt and grime from the top of the chassis. Windex moistened Q-Tips work great for getting into hard to reach areas. I only clean the tops of the vacuum tubes as I don't want to remove the markings from the sides of them.
I use Labelle 107 oil to lubricate all of the pulleys for the tuning dial indicator. This oil is safe for plastics. I have this oil on hand for my model train hobby.
I also use Labelle 107 oil to lubricate the shafts of the vintage Volume potentiometer and Tone switch.
I use Labelle 106 Grease to lubricate the bearings of the Tuning capacitor. The red arrows indicate the location of the bearings.
Contact cleaner is used on all electrical contacts, like where the potentiometer wiper contacts the resistive element in the Volume control. I then rotate the Volume control back and forth several times.
Labelle lubricants on Amazon
I use Labelle oil and grease for my radio restoration projects. I already have these products around as I am also a model railroad enthusiast. These products will not harm plastic.
Step 3 Test Vacuum Tubes
Unlike semiconductor transistors that have a near infinite lifespan, vacuum tubes age and become less efficient. In addition, their filaments burn out rendering them inoperable. It is always a good idea to test all vacuum tubes in a radio you are servicing before doing any more troubleshooting.
In addition, make sure that that the right tube is in the right socket. This will save you troubleshooting time later.
Pictured below is my Eico Model 635 Vacuum Tube Tester testing a tube from the RCA Victor 15X radio:
Step 4 Rewiring and Capacitor Replacement
As electrolytic capacitors age, their electrolyte dries up, causing their electrical capacity to drop and leakage current to increase. Circled below is one of two electrolytic capacitors used in this radio.
Electrolytic capacitors should be replaced with one of similar capacitance and equal or above voltage rating.
It is definitely a good idea to replace all electrolytic capacitors in a 74 year radio, such as this RCA Victor 15X.
Molded paper capacitors, like the one circled below, become very unreliable with age and should be replaced with one of similar capacitance and equal or above voltage rating. Molded paper capacitors are not polarized although they may have a black band on one side indicating which lead is connected to the outside foil. I replace molded paper capacitors with new Polypropylene type.
The chassis wiring was complete mess in this radio. Some components weren't even soldered in place!
At some point the electrolytic capacitors were replaced. Their leads were just twisted to a wire and covered in electrical tape.
Some component leads were twisted around tube sockets pins. It looks like several "novice" repairmen tried to fix this radio with little success. See the carnage below:
I couldn't trust any of the wiring in the chassis of this radio. I double checked and corrected all wiring during the process of replacing electrolytic and molded paper capacitors. I am rather pleased with the results. See the picture below:
Step 5 Trimmer Cap Replacement
There are two compression-type trimmer capacitors built into the Multi-section Tuning Capacitor. They are adjusted by screws, circled below. The top screw adjusts the LO (Local Oscillator) Frequency, the bottom screw is the Antenna Trimmer. The screw holes were badly stripped out an neither setting could be properly adjusted.
I replaced the built in trimmer caps with two external trimmers of the of same capacitance range (3 to 25pf) See new trimmer capacitors circled below:
Step 6 Tone Switch Repair
The RCA Victor 15X incorporated a Tone on/off switch instead of a potentiometer. The wiper contact of the switch was missing.
I fashioned a new wiper contact out of a spade lug soldered to the end of the shaft. I also drilled small holes and installed a terminal pin, bent into a U-shape, to limit the travel of the switch. The U-shaped terminal pin was held in place by a dab of Superglue. The red arrow is pointing to the travel stop in the below picture.
Finally, I painted my repair with silver enamel hobby paint to make it less noticeable. I did not paint where electrical contact is made.
Step 7 IF Transformer Resistance Checks
Circled below is one of two IF (Intermediate Frequency) transformers used in the RCA Victor 15X.
As part of my restoration steps, I perform resistance checks using my Multimeter on the primary and secondary windings of all IF transformers. This can be done with the IF Transformer still wired into the radio circuit. The resistance accross the primary or secondary windings should be 50 Ohms or less. I noticed that the a winding of the 2nd IF Transformer had an open. Click on the link button below to see my blog on how I repaired it.
Step 8 Dealing with Chassis Rust
My RCA Victor 15X radio had a fair amount of rust on the chassis.
The first step to chassis rust repair is to give yourself some room to work. I removed the vacuum tubes in the near proximity. I also to unsoldered the wires that connects to the pilot light and then pulled the wires through the feed-through hole.
I started with a Dremel with a grinding wheel installed to remove as much of rust as possible. I then sanded the rusted area starting with coarse sandpaper finally finishing with a fine sandpaper.
It is important to perform paint prep before applying spray paint. I masked off the area to be painted. I used denatured alcohol to degrease the area before paint.
I use silver Dupli-Color automotive rim paint as it is the closet color I can find that matches the natural color of most chassis. Apply in light coats and feather it out so as to make a natural transition from the newly painted area to the chassis color.
Repair job complete! Time to install a new grommet in the hole then thread the pilot lamp wires through the grommet and solder to the proper rectifier tube socket terminals. The final step is to install the vacuum tubes into their respective sockets.
Duplicolor Rim Paint on Amazon
I use this paint to touch up places on the chassis that have rusted.
Step 9 Tuning Dial Back Plate Refinishing
The Tuning Dial Backplate, circled in the picture below, was in need of refinishing.
I removed the Tuning Dial Backplate assembly from the chassis and then sanded the area to be painted with a fine grit sandpaper. I then masked off the area to be painted and wiped it down with de-natured alcohol to remove any residual grease.
The next steps were to apply automotive primer and then lightly wet sand, once the primer is dry.
Finally, a leather brown top coat was applied. Once dry, the Tuning Dial Backplate assembly was re-attached to the Chassis.
Step 10 Dial Cord Replacement
The Dial Cord, Tension Spring, and Dial Pointer were missing from my RCA Victor 15X Radio. I fashioned a new Dial Pointer from a Terminal Pin and Solder Lug I found in my junk box.
I painted the newly fashioned pointer red using Enamel hobby paint.
Most radio schematics include a diagram on how to string the Dial Cord.
I used a spring from a battery holder as the Tension Spring.
Finally, the Dial Cord replacement is complete. I will not attach the Dial Pointer to the Dial Cord until reassembly, so that I can properly align it in the Tuning Dial Window.
Step 11 Cabinet Repair
I do not like to apply paint to a Bakelite cabinet as I feel it covers its natural beauty, but feel I didn't have a choice in the matter due to the large jagged crack, with small pieces missing, on the side.
Click on the link button below to see my blog on Bakelite Cabinet Repair.
Below is a picture of the newly repaired RCA Victor 15X Cabinet.
As finishing touch, I spray the paint that I used on the radio cabinet into the lid. I then use a fine paint brush dripped in the paint and apply it along the back edge.
Step 12 Assembly
The first step in the assembly process is to reinstall the Tuning Dial Window. A screw on each side holds it in place.
Then the chassis is carefully slid into the back of the cabinet. It is held in place by two screws, one on each side of the chassis.
At this point I install the knobs, then I rotate the Tuning knob counter-clockwise until I see that the Tuning Capacitor's plates are fully meshed. The next step is to move the Dial Pointer along the top of the Dial Backplate until it shows the lowest point on the Tuning Dial Window. I then affix the Dial Pointer to the Dial Cord with a dab of Superglue.
Next, its time to consult the schematic and solder the wires to the built in antenna. There are also two connections that go to an RCA Jack that allow you to use the radio as an audio amplifier.
The internal antenna is attached to the Chassis with two screws, circled below. I sprayed painted the fiberboard piece that the internal antenna attaches to a matt black.
Finally, a picture of the finished product! I still need to find a replacement knob for the Tone control.
I spent many hours restoring this vintage RCA Victor 15X Radio. It was satisfying bringing it back to life. Watch the video below to see my newly restored radio in action.
Who Writes This Blog?
John is an IT professional from Cleveland, OH who enjoys amateur radio, ham radio, metal detecting,
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