NuTone Model 2540 Solid-State Radio Intercom
Saturday, February 9, 2013 at 3:43PM “Thrill to the sound of NuTone FM/AM radio, with room and patio speakers throughout your home. The NuTone 2540 offers extra features usually available only in expensive decentralized system. . . The 2540 has advance solid state design, with FET transistor FM Tuner, selector switches for up to 10 remote speakers, person being called can answer without operating any speaker control. . . “
The NuTone 2540 would be considered the second generation of solid state NuTone Radio Intercoms. By this time all of the Vacuum Tube based designs have been discontinued and with the introduction of the new 1968 models NuTone was on track to build a solid foundation for the future.
NuTone introduced new terms to the world of Radio Intercom systems like: Centralized and Decentralized Systems, Master All Call, Stand-by Intercom and “Hands-Free” Door Answering.
These new features set the standard for the new models and they still are incorporated in today's designs.
The NuTone 2540 would share the top spot in the model lineup with the ultra-rare model 2542 and the long lasting N2561-62.
There were many choices of speakers for inside and outside stations which allowed the 2540 to be customized by the homeowner.
2540 – 2541 Master Stations: The master station was available in 2 finishes, Walnut and Egg-Shell. Each model features matching grill cloth for that “high-end” audio speaker look.
2550 Inside Speakers: The 5” inside speakers were available only in egg-shell and include a rotary volume control and both “Inside” and “Door-Answering” intercom pushbuttons.
2553 Inside Speakers: These 8” Hi-Fidelity speakers came in Walnut or Egg-Shell with matching grill cloth for that high-end look. The 2553's featured a removable “break-away” control panel that could be mounted into a separate wall housing which would allow the actual speaker to be mounted in a more central location for better sound.
2556 & 2557 Patio Speakers: Patio speakers came in 2 sizes, Large and even larger. The 2556 is a 13” x 13” aluminum grill with a 8” diameter speaker cone. The 2557 is a dual range, surface mounted broadcast speaker horn, which can produce some impressive volume. Both of these types of Patio speakers included a Patio Remote control for volume adjustment and Intercom controls. The patio remote control mounted in a N2013: Patio Surface Mount Weather Shield.
Door Speaker 2571: The 2571 is a built-in Gold & Black Entry Door Speaker without any intercom switch. All door communications for the 2540 are control from the inside stations. A surface mounted door speaker was also available, it was Model 464 and it included a built-in door chime pushbutton.
Common Problems with the NuTone Model 2540:
The 2540 is a simple and very reliable model of NuTone Radio Intercom and most of the systems we see have simple “age related” problems.
Hum on the 2540 Master Station:
As with all older NuTone intercom master stations age is the enemy and it takes it toll on the components in the power supply. These early NuTone designs have a built-in benefit that later models don't have, these have a turn “on/off” switch.
When the volume control on a 2540 is rotated counter-clockwise and clicked “off”, the system and the 2540 master station are truly off. One of the reasons these NuTone models last so long without any repairs is because they spend a lot of the turned off.
Over time the 2540 will develop a hum and as this hum gets worse it will effect how the system operates. The tuners will be affected and the radio reception will worsen along with a decrease in volume.
The final stage will be the disintegration of resistor R48 on the main circuit board.
Repairing a 2540 is a pleasure with a few exceptions. Rebuilding the power supply is simple, however most of the components are older values and older axial parts. These types of parts are still available and a proper rebuild should include the correct parts.
One part that is not commonly available is the multi-section filter capacitor on the amplifier board. This is a very outdated style of part that is not manufactured much anymore.
While it is possible to mount several individual capacitors in place of the single can, this will be a messy and less than ideal repair.
The best choice is to “restuff” the original can with new components. “Restuffing” involves cutting the can open, removing the contents and then mounting new capacitors inside the can. When the can is resealed you won't be able to tell anything has been changed. It is worth the effort and it's not really that difficult to do.
Another part of the 2540 which can cause problems is the FM Tuner. Its not uncommon for the FM tuner to become either weak or out of alignment with age. It's also not uncommon for the FM radio to play at one-half the volume of the AM radio. This is of course not right, both the AM and FM should play at the same level.
Working on the FM tuner module requires it to be removed from the chassis plate to have access to the solder side of the circuit board. This board is difficult to work on because it is mounted down inside its shield box and there are many small components on the board.
If the tuner requires alignment, specialized equipment is required and this should be left to someone with experience.
Once the electronics have been repaired, the controls on the 2540 master should be cleaned and the dial lamp will need to be replaced. The correct lamp is a miniature lamp #1829.
Look Through the 1972 NuTone Intercom Catalog
See all of the Model 2540 Pictures Here
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