First – There are several Basic Rules which must be followed when you have acquired an old piece of electronics or have rediscovered grandma’s old radio:
1. Do Not Power Up an Old Piece of Equipment until it has been checked over!! There are components in there which have certainly deteriorated over the past 50 to 80 years, and some of those can cause very severe damage to the device and its other components.
2. Be Aware That Electronic Devices Contain High Voltages That Can Cause Severe Injury or Death.
Old RCA radio in for repair.
When an old device comes into the shop, the typical repair steps will be to:
• Obtain a service manual or schematic for the device, invaluable for troubleshooting and aligning the gear. We have an extensive library of Sams Photofact literature, as well as original manufacturers data, and other documents such as Beitman’s, Rider’s, etc.
• Clean and inspect the chassis for obvious damage or failed components, such as burned resistors, leaky capacitors, etc. It is common for power cords and also certain other chassis wires to become brittle and cracked, these must be repaired before power is applied.
• Replace defective electrolytic and wax paper capacitors. Defective electrolytic capacitors in a device’s power supply can destroy power transformers and other parts. They can also cause a 60hz hum that can not be silenced by turning the volume down.
• Check resistors to see whether their values are within tolerance, and replaced if not. Before removing components from under a chassis, we photograph the area to help get everything reconnected correctly.
• Test tubes to see whether any need replacing. We have a large stock of tubes on hand.
• Clean tube sockets, switches and controls. These become oxidized over time and cause symptoms such as scratchy sound when changing the volume.
• Raise the voltage slowly. When these checks have been completed, the radio can be powered up, but preferably through a metered variac, raising the voltage slowly and watching for incorrect high current draw.
• Check IF transformers. If the radio produces loud static similar to lightning, the IF transformers likely have SMD (Silver Mica Disease) and must be replaced or repaired.
• A general alignment may be needed, depending upon the parts replaced.
If a record changer is part of the system, then:
• Operation of the changer will be evaluated for sticking change cycles, incorrect speed, etc.
• Grease lubrication which may have hardened up over the years in an old record changer often needs to be cleaned away and replaced.
• Replace or recondition idler wheels which may have developed hard, slippery surfaces.
• Check cartridges and needles and replaced as necessary.
• Miscellaneous checks and adjustments, such as the tracking force and alignment of the cartridge must be made.