Inspection - A Tour of a Vintage Radio
The first step in a restoration is a careful inspection to indentify possible problem areas. The radio in this
example is a classic Philco Model 60. This style of radio is known as a cathedral, and it was one of the
signature art deco styles from the mid 1930s.
You can see from the wear pattern around the tuning and volume control
knobs that this radio received a considerable amount of use. This clearly wasn't just a piece of decoration- this
was a well loved and well used set.
Looking at the back of the radio, it is clear that it hasn't seen use in many decades. The repair tag on the
radio is from a small radio repair shop in Illinois, and is dated from the late 1940s. There is also a significant
amount of dust and debris, which is typical of radios from this era.
Step 1. Chassis Removal
Removing the chassis is accomplished by removing the knobs from the front of the radio and removing four screws
from the bottm of the cabinet. The chassis can then slide out from the back. Most knobs can be pulled straight off the
corresponding shaft. Occasionally you will find a knob that is held in place by a set screw.
Many vintage radios have rubber washers between the chassis and cabinet. Over time these washers dry out, which
causes problems with the alignment of the radio dial and eschuteon. Replacement washers are available from several
retailers listed on the Links & Other Resources page. Now is a great time to start a list of parts to be ordered.
In this particular radio, the speaker and audio output transformer are hard wired
directly to the chassis. For the moment, I'm going to leave the speaker in place and carefully handle the chassis
with the wires still attached.
The top side of the chassis appears dirty but very much restorable.
Step 2. The top of the chassis
In the following picture, the major components on the
top side of the chassis are labelled. During the restoration process, each of these components needs to be check thoroughly and
repaired as needed.
In time, we hope to provide restoration hints for each section of the radio. For now, here is a brief description
of the parts you may find on the top side of the chassis:
- Vacuum Tubes - The workhorses of vintage electronics. Each tube needs to be checked with a tube tester
prior to use. If you don't have a tube tester, you may be able to find an antique radio collector club in your area.
Most clubs are happy to help.
If you need a replacement tube, check some of the suppliers on our Links & Other Resources page.
- Power Transformer - Generally large and black. These may be absent in later radios.
- IF Transformers - Most IF transformers are housed in aluminum cans with adjustment screws on the top.
Some early radios, such as this one, have the adjustment screws on the chassis.
- Tuning Capacitor - These are large variable capacitors used in the tuning and oscillator circuits
- Dial light - The lack of a working dial light can cause problems with some radios. It's always a good idea
to check and replace the light as needed.
- Electrolytic Capacitors - These are the large capacitors used in the power supply circuit to convert AC into DC.
Early radios used wet electrolyte, and this almost always dries up over time. It can be very dangerous to power up a set
without first restoring the electrolytic capacitors.
Step 3. The bottom of the chassis
Most of the wiring and electrical components are beneath the chassis. Always use extreme care when working on vintage
electronics, as high voltages are present. If you aren't sure or need some help, try contacting your local antique
radio club or hiring a professional.
The resistors, capacitors and inductors used in vintage electronics serve the same functions as their modern counterparts.
However, their size and shape has changed drastically over the years. The following picture contains labels for each of the major
parts. Many of the early radio components were not standardized, and can sometimes have different appearances depending on the
- Wirewound Resistor - Often used in the power supply voltage divider circuit
- "Dog Bone" Resistor - One of several styles of carbon composite resistors. These often drift out of tolerance
- Capacitor Bank - Several wax/paper capacitors in the same housing. This should always be rebuilt.
- Variable Resistor - Commonly used in the volume control circuit, these generally need thorough cleaning.
- Replaced Capacitor - It's rare these days to find an old radio that hasn't been serviced or modified. It is important
to identify any changes that have been made in order to determine what steps are necessary for restoration.
- Wax/Paper Capacitor - These are an older technology that almost always fails with age. They come in several shapes
and sizes, and should always be replaced. In this particular set, all of the wax/paper capacitors are either the Philco Bakelite
variety or are part of the capacitor bank.