Troubleshooting Guide – Retro Radio Farm

Troubleshooting Guide

Thank you for your purchase!

Recommended Use:

 Please refer to online listing for specific information for your particular radio. Depending on the particular product you purchased, some or all of the information below may or may not apply.

Your radio is an antique electronic device that has been recently serviced and repaired by Retro Radio Farm ( The electronic circuitry of your radio has undergone complete repair and rigorous quality control but the original circuitry has not otherwise been altered or redesigned. In the interest of preserving authenticity, your radio electronics has not been refurbished with modern solid state or digital technology. Vacuum tubes are a scarce and obsolete component needed in the operation of your radio. There are no existing manufacturers of these vacuum tubes today. All vacuum tube supplies are remaining original stock from many years ago left over from old radio dealers and repair stores or their newly discovered old inventories. Once these supplies are depleted, your radio will not be able to function as it was originally designed.

Currently, there is an abundance of sellers online for old vacuum tubes (i.e. Ebay,, etc). The numbers may be hard to read. Sometimes fogging up the glass by breathing on it will help show the faded numbers. The vacuum tubes you will find in your radio are the typical All American 5 (AA5) consisting of:

1950's (glass 7-pin):

35W4 - rectifier.  Approximately 1-1/4" - 1-1/2" height.

50C5 - amplifier.  Approximately 1-1/4" - 1-1/2" height.

12AU6 or 12AV6 or 12AT6 - AVC/Modulator. Approximately 1" height. Not interchangeable

12BA6 - preamp. Approximately 1" height.

12BE6 - Converter. Approximately 1" height.

As long as the glass is intact, it is difficult to tell whether a vacuum tube is dead or defective by visual inspection. A circular brown burn stain is normal. A shiny, chrome-like, deposit on the inside of the glass tube is also normal. A milky white deposit on the inside of the tube normally indicates a vacuum leak.

1940's (glass or black metal 8-pin):

35Z5 - rectifier. Approximately 2" height

50L6 - amplifier. Approximately 2" height

12SQ7 - AVC/modulator. Approximately 1-1/2" - 1-3/4" height.

12SK7 -preamp. Approximately 1-1/2" - 1-3/4" height.

12SA7 - Converter. Approximately 1-1/2" - 1-3/4" height.

None of these vacuum tubes are interchangeable even though they can plug into any of the sockets. Vacuum tubes plug straight in. They are not screwed in like a light bulb. You cannot substitute any of the tubes (i.e. 12AU6) with another of different code (i.e. 12AV6). Any vacuum tube manufacturer of the same code (i.e. RCA 50L6) can be used interchangeably (i.e. Sylvania 50L6). You should be extremely careful when you plug these tubes into their sockets and when you remove them. Remove vacuum tube by gently prying from the base. Be careful not to bend the pins. When installing, be careful to line up the pins. Do not force. The brown stains on the inside of the glass are normal. Some vacuum tubes came from the factory with the brown staining. The chrome silver staining is also normal. These stains do not mean the vacuum tubes are defective or blown out. A milky white stain means the vacuum tube is defective or weak. If the tubes glow at all, it means the vacuum tubes are probably ok.

Technological advances in consumer electronics and manufacturing has grown by orders of magnitude since the time your radio was originally manufactured. Modern electronics are more safe, reliable, and inexpensive to buy and maintain than their earlier counterparts. You should not expect this old radio to be as reliable as your modern electronic device. Your radio was originally made by hand to some degree, or for the most part. As such, quality control even when it was brand new was unpredictable at best. Add to that, these radios were probably stored and transported throughout the last 50-70 years under various conditions and exposed to moisture, insects and vermin, dust and dirt, extreme heat and cold, for extended periods of time.

Use standard household line voltages (110V-120V).  Do not use on wet surface or metal surface. If radio is wet or submerged, pull plug out and wipe dry before plugging in. Do not drop radio or subject radio to repeated vibration or shock.

Your radio should provide years of trouble free service, but it is not recommended for prolonged periods of continuous use. Do not leave radio on unattended for long periods of time.

Never put your fingers inside the back of the radio when it’s turned on. The radio runs on high voltages and high heat. Electrical shock, burns, injury, or even death may result from direct contact with the electrical components of your radio while it is plugged in.

 Turning your radio on:

Your radio takes approximately 15-30 seconds to warm up. You should be able to see the tubes glowing orange if you look in the back. It should not take more than 1 minute to warm up.

Tuning your radio to a radio station:

Your radio was designed to receive AM signal transmissions between 550KHz to 1650 KHz. If you cannot tune into your station, the radio may be out of receiving range. An AM broadcast can only be received within a certain distance approximately 10 miles to 30 miles form transmission point. Try tuning into the same station with another AM receiver as a test. Being able to receive satellite or WiFi does not mean you will be able to receive AM as the technologies are different.

MP3 Option:

If your radio has been adapted for MP3 or auxiliary audio input option, you will see a RCA input jack on the back or side of the radio chassis or cabinet. The radio accepts audio input from iPhone, iPad, MP3 player input using a 3.5 mm to mono RCA cable which is included. Switch from radio to auxiliary audio input using the toggle switch located on the back panel. If your radio is equipped with a 3 position toggle switch, it is not recommended to keep the toggle switch in center bypass position with loud volume for extended period of time. If you radio was originally designed with an auxiliary audio input, just plug into the RCA input jack with the 3.5mm-to-mono RCA cable included. You may need to adjust volume level when you switch from auxiliary to radio and back.


 Radio Related



Won’t turn on

Make sure the outlet power is on. Some outlets are wired to the wall switch. The power to the outlet is not on until you turn on the wall switch. Test outlet with a household lamp


Tubes are loose or have come out of socket. Unplug power cord and inspect all sockets. There should be 5 tubes. If you remove tubes, you must be sure to put tubes back into the correct socket. It does not matter what order you put tubes back into sockets. However, if you put tubes back in wrong sockets you may burn out one or more tubes and destroy your radio.

The plug is not making a connection with the outlet. Bend tangs slightly until tubes glow orange.

If your system is a clock radio, the little clock knobs on/off operate on a mechanical cam. The cam is worn over the years and the on/off positions are not factory specifications. You will need to 'find' true on position by 'jiggling' the switch or 'fidgeting' with the on/off switch until it actually turns on. You will need to find this exact position moving forward to turn the radio on. The switch actuator was restored at RRF on a best effort basis. In order to fully reburbish the switching mechanism, the components would require replacement with a digital technology. No mechnical based technology was replaced at RRF during our restoration and repair process for the sake of originality.

The power cord has an internal break and wires are not connected. This usually happens at the interconnect junction where mechanical fatigue of back and forth mtion causes cable to break inside the plastic cord sheath. The power cord will need to be replaced.

Tubes glow but no sound

May need longer to warm up.


One of the tubes may be defective, burned out.


One of the speaker wires has been disconnected.

One of the tubes is not properly seated or not making a connection.
If someone has replaced the tubes and put them back in incorrectly, your tubes could be damaged irreparably. One of the tubes might be blown now. Ebay has tubes plenty at $5-20 each. Be sure to get the tube codes that matches yours exactly. The tube diagrams are always tops down. Make sure you have correct orientation 0 to 180 deg. Most tube diagrams reference orientation of 5 tubes like a keyed pattern. The pattern is only correctly sense one way. 

Tubes glow but volume very low

One of the tubes is weak


Antenna wire has been disconnected. You can open the back fiber board panel and check the two wires are connected to the antenna coil. Inside the radio, the two antenna wires are connected to the tuning capacitor which is the component with metal plates that turns when you adjust the tuning knob. One antenna wire always connects to one of the tuning tangs on the top of the tuning capacitor. The other antenna wire connects to the metal block housing of the tuning capacitor.

Bad reception

AM radio stations turn their transmitter down past 8PM nationwide in the USA. You will hear a loud buzzing or humming noise. If the radio is close to a TV, cable box, computer, or modern day appliance.


Re-orient the radio facing a different direction and try different locations in your house.


Radio may need an external antenna wire. Most of these old radios were fitted with an external antenna attachment on the backing board. It will be a flathead screw and may even be labeled for external antenna.

Scratchy noises

Dirty electrical contacts. All components have been thoroughly cleaned when your radio was serviced. However, exposure to dust, particles, and moisture even with normal use and care can result in scratchy sounds when you turn the volume and tuning knobs. A good way to clean these contacts is with electrical cleaner found at most auto supply stores. Always make sure the radio is not plugged in when you clean your radio with any kind of cleaner. Makes sure the cleaner has thoroughly dried before turning radio back on.

Warbly sounding, motorboating, pulsing sound

Your radio will need service from an experienced repair person.

Your vintage radio was expected to be 'routinely' maintained by a service professional. Back in the day, TV and electronics service professionals drove around like cable guys of today. The symptom here is an alignment issue. The components in your radio have 'drifted' from factory and RRF service calibration which is expected after continued use in which your radio has been subject to normal cycles of heat and cooling, power on and power off. 

Radio plays fine but stops playing completely after a while

One or more tubes may be weak. Vacuum tubes are a consumable and by design were intended to be replaced by the consumer from time to time.


There is an issue with an electrical connection and will need service from an experienced repair person

One of the circuit connections has opened. The age and handling of your radio over the years has caused one of the circuit connections to open. This is not something an untrained person can find. It will take reflowing the solder points and inspection under magnificiation to remedy.

Radio plays but stops playing and a crashing sound is heard

Your radio will need service from an experienced repair person.

Over time, the intermediate frequency transformers (IFT) of your radio will stop working. The continued current flow causes the mica capacitors in IFTs to 'bridge' forming a connection. The only remedy is to replace these IFTs with replacement 455Hz IFT. You can try rewindinf these IFTs but it's not for the weak of stomach or those with poor eyesight. You will need to re-align afterwards. One of the most satisfying moments of antique radio repair, however, is one on the moments when an IFT is repaired or replaced, and it gets 'tuned' to 455Hz. The volume get loud and clear with a turn of a screw!

Ghost transmissions are heard. Hear two radio stations one over the other.

Your radio will need service from an experienced repair person.

 Radio smokes!

Turn radio off immediately. Short circuit. Moisture contamination. Blown tube causing capacitors to fry. 


I need the tune layout diagram

Here are sources for tube diagrams:


Clock Related:

 Issue Resolution
Clock is 4 hours behind every 24 hrs Clock motor is designed to run at 60hz in order to keep accurate time. You will need a 50Hz to 60Hz converter. They are more expensive than the $40 USD power converters typically found. A 220V 50Hz to 110V 60Hz converter might cost $150 USD.
Clock is noisy Your clock runs on a motor that is not perfectly silent like modern digital technology. There will always be some sound associated with your clock design. Your clock runs on a sealed motor that is not serviceable by the user. The clock mechanism must be replaced if it is inoperable or excessively noisy. 


Bluetooth Related:

 Issue  Resolution
Bluetooth won't pair Bluetooth is already paired with another device. You must unpair with the other device. Bluetooth receivers can only pair with one other device.
Audio quality is poor through the Bluetooth receiver but plays fine when connected directly to source

The Bluetooth receiver battery is weak or near End of Life.

One of the tubes is weak

Bluetooth receiver stops working 

The rechargeable battery inside is end of life.

Inexpensive replacements are readily available on Amazon or Ebay. 

Search for Taotronics, MPow, Belkin Bluetooth MP3 Receiver

Bluetooth receiver turns off incessantly. Won't hold charge. The battery in the Bluetooth receiver is End Of Life. Inexpensive replacements can be found on EBay and Amazon. Search for 'Bluetooth Receiver H166.' White or black is compatible. 






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