Here is a before and after picture of my vintage Zenith Consoltone Model 5D011Z Radio. I think you'll agree that the makeover was a complete success!
About my Zenith Consoltone radio
I paid $12 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 end of the shaft of the combination Tuning/Volume/Power control was sheared off (circled in red below). This is a specialized potentiometer/switch and will hard to find an exact replacement.
3.The power switch knob was missing. Most collectors know how hard it is to find matching knobs.
4. The cardboard back panel was in rough shape.
"Old Time Radios! Restoration and Repair" book on Amazon
I consult this book often during radio restoration. I grew up in the transistor and diode era and this book taught me a lot about vacuum tube and selium rectifier technology.
Step 1 Remove Chassis from Cabinet
The Zenith Consoltone uses only two screws to hold the chassis in the cabinet. One on each side of the chassis. The tuning knob must be removed first. It just pulls off. As mentioned, this radio is missing the Power/Volume control knob. Once the screws and knobs are removed, the chassis slides straight out of the back of the cabinet.
The tuning dial window and speaker grill are held in place with what I call "compression rivets", four each (circled in the picture below). You simply use a small screwdriver to pry them out from under the head of each rivet.
Handle the tuning dial window with care as it is made from some brittle predecessor to plastic and can easily crack.
I removed both the tuning dial window and speaker grill to clean them and to prep the cabinet for repair and paint.
Step 2 Chassis Cleaning and Lubrication
I removed the internal spider web antenna and antenna bracket from the radio chassis. You must desolder the two antenna connections from the tuning capacitor before it is free and clear. Removing the antenna and antenna bracket made handling the chassis during the cleaning and repair easier.
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 combination Tuning/Volume/Power control.
I use Labelle 106 Grease to lubricate the bearings of the tuning capacitor.
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 Zenith Consoltone.
Step 4 Electrolytic Capacitor Replacement
As electrolytic capacitors age, their electrolyte dries up causing their electrical capacity to drop and leakage current to increase. It is definitely a good idea to replace 70 year old electrolytic capacitors like the ones in the Zenith Consoltone!
Step 4a - Restoring the Multi-Section Capacitor
Multi-section capacitors, which were aluminum cans containing several discrete capacitors all connected to a common ground, were popular in the 1940s. There were used mostly in the power supply sections of vintage electronic devices. You can purchase replacement multi-section capacitors but they are expensive. I typically rebuild them by replacing their guts with inexpensive discrete capacitors of the same or slightly greater capacitance and working voltage. The multi-section capacitor in the Zenith Consoltone is circled in the picture.
The multi-section capacitor in the Zenith Consoltone contains the following discrete capacitors:
Capacitor A 20uF @ 150Volts
Capacitor B 20uF @ 150Volts
Capacitor C 40uF @ 150Volts
The components connected to it's base terminals, circled below, must be desoldered before removing it from the chassis.
Here is a picture of the multi-section capacitor removed from the chassis. The three solder lugs in the center connect to the positive side of the internal electrolytic capacitors. All internal capacitors share a forth common solder lug at the rim for their negative connection.
I use wire cutters to uncrimped the bottom of the multi-section capacitor. Then I use needle nose pliers to pull the crimped sections away from the base. This allows me to pull the guts of the multi-section capacitor out of the aluminum can.
The anatomy of a multi-section capacitor. The three internal electrolytic capacitors are rolled up into one assembly.
I was only able to fit the replacement 47uF electrolytic capacitor inside the aluminum can, the other two 22uF electrolytic capacitors will be soldered to solder lugs and concealed in the chassis.
The aluminum can, when glued in place, will conceal the replacement capacitor.
Pictured below is the refurbished multi-section capacitor installed back into the chassis. You will never know it was refurbished once the aluminum cover is installed!
I use a Dremel with cutoff tool to remove the area from the base of the multi-section capacitor's aluminum can that I bent with needle-nose pliers. I then use the Dremel with wire brush tool to remove burrs.
I spray the external cardboard wrapper of the multi-section capacitor's aluminum can with some flat black paint to make it look as good as new.
Hot glue holds the aluminum cover in place over the multi-section capacitor's base.
Step 5 Replacing Paper Capacitors
Paper capacitors, like the ones 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 paper capacitors with new Polypropylene type. Circled in the picture below.
Step 6 Combination Control Repair
The Zenith Consoltone uses one control that incorporates Tuning, Volume, and Power functions.
As mentioned, the part of the shaft that controls Volume and Power had sheered off. This is a rare part and it will have to be repaired instead of replaced.
I needed to somehow extend the end of the shaft so that it could accommodate a knob. The first thing a did was drill a small hole at about 3/8 depth. I then inserted a copper pin and soldered it to the brass shaft. This would give my shaft extension some mechanical strength.
I then soldered the base of a crimp lug to both the copper pin and to part of the exposed shaft.
Finally, I cut a slit in the plastic insulator of the plastic lug then super glued it in place on the shaft. This will give the shaft extension the proper diameter for the knob to fit snuggly in place. The slit will allow the set screw of the knob to contact metal giving it a secure hold.
Step 7 IF Transformer Resistance Checks
Circled below are the two IF (Intermediate Frequency) transformers used in the Zenith Consoltone.
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 repair the Transformer if I notice that the a winding has an open. Click on the link button below to see my blog on how I repair them.
Step 8 Pilot Lamp Replacement
It is important that you have a working pilot lamp. The Zenith Consoltone requires #47 Lamp. A failed pilot lamp could cause premature failure of the 35Z5GT Rectifier Tube.
Step 9 Initial Testing and Polarized Plug Install
Time to install the vacuum tubes and do initial testing. But before I start testing I install a polarized plug on the end of the power cord. An 120 Volt AC line voltage potential can be on the metal chassis, which can pose an electrocution risk, depending on how the non-polarized AC cord plug is plugged into the power outlet.
I replaced the plug with a polarized one that most closely matched the original. The wider blade should connect to the Zenith Consoltone chassis as this is the Neutral connection. The thinner blade connects to Hot.
With the Zenith Consoltone is plugged into an electrical socket, you should detect only a very low voltage (less than one Volt) AC between the ground connection on the wall socket and the chassis. I used test leads with alligator clips to temporarily connect the spider web antenna.
Success! The Zenith Consoltone immediately picked up a local AM broadcast station once warmed up.
Step 10 Cabinet Repair
I do not like to apply paint to a Bakelite cabinet as I feel it covers its natural beauty, but I 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 Zenith Consoltone 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.
I used a sharp stick dipped in gold enamel to paint the Consoltone logo on the front of the cabinet.
I spray painted a knob I found in my junk box the same color as the cabinet, this will be the new Volume/Power control. I once again used sharp stick dipped in gold enamel to paint the position indicator line on the knob.
I use silver enamel paint to brighten up corroded screw heads after they have been lightly sanded.
I decided to paint the spider web antenna assembly a matt black as this is what you will see from the back of the radio.
The original back panel was too badly damaged to repair. It will not be installed on my restored Zenith Consoltone.
Meguiar's PLASTX works great for restoring old tuning dial windows.
I then use Meguiar's Quik Glass for a streak free shine on the tuning dial window.
Meguiar's Product on Amazon
Meguiar's Automotive Wax and Cleaning products work great for detailing vintage radios!
The original gold speaker grill cloth looked pretty shabby. I replaced it with a new black speaker grill material I had lying around.
Step 11 Assembly
The first step in the assembly process is to install the red pilot lamp lens. A couple dabs of Superglue hold it in place.
The next step in the assembly process is to reinstall the tuning dial window. Four compression rivets hold it in place. I had to install washers under the compression rivets as the tuning dial window had shrunk over the years.
Four compression rivets also hold the speaker grill in place.
The spider web antenna needs to be reattached to the chassis before it can be installed in the cabinet.
It is held in place with one metal bracket. The two wires from the antenna connect to terminals on the tuning capacitor.
There is one wire on the external side of the antenna that connects to the metal bracket.
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, I install the outer tuning knob first. Then, I install the inner Volume/Power knob. The set screw must be positioned so that it comes in contact with the metal shaft and not the blue plastic spacer I created.
Finally, a picture of the finished product!
I spent many hours restoring this vintage Zenith Consoltone. It was satisfying bringing it back to life. Watch my 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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