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Are You Living with a Discolored and Yellowed NuTone Master Station?

Has Your NuTone Radio Intercom Master Station Discolored and Turned Yellow?

A big problem with many models of NuTone Radio Intercom Master Stations are that over time the Master Stations discolor and turn from their original White or Bright White to a sickly yellow.

This happens due to a complex chemical reaction in the plastic after it has been exposed to Ultra-Violet light from the sun.

Many types of plastics used in consumer products are made from a formula that includes the chemical compound Bromide. Bromide is added to the plastic to help make it more fire-retardant.

When the plastic is exposed to UV light for a long period of time, the bromide (which is a naturally brownish color) reacts and slowly turns the plastic into a yellowish color. The yellowing effects only the surface of the plastic, keeps the original color just below the surface

This yellowing of plastics is very common, especially with consumer products made in the early 1980's through the mid 2000's.

Many of the NuTone Master Stations we receive in the shop for repair are severely discolored. Even after the electronics are repaired and the faceplates have been cleaned, the yellowed faceplate makes the Master Station look unsightly.

As it turns out, there is a process that can reverse the chemical reaction in the plastic and restore the face plate almost to it's original color.

By using a mixture of concentrated Hydrogen-Peroxide, Oxy-Clean, Water, Sun Light and Time, the yellowing process can be reversed.

I have started some trials on the face plate from a NuTone IMA3303WH, which originally was NuTone's “Bright White” finish. My test face plate had discolored to a sickly yellow that no one would want in their kitchen.

As a control for the test, I removed one of the lower doors from the IMA3303's face plate and put it aside. The face plate (with all of the electronics removed), the second door and the push button assembly were place is a transparent plastic tub and the de-yellowing solution was added. A tight fitting lid was placed on the tub and everything was placed outside in direct sunlight. The test began on Saturday, May 3rd at 6 PM.

Red Arrow is untreated door - Blue Arrow is treated door

The pictures which shows the outcome of the test were taken on Sunday, May 4th around 4 PM, which is slightly less than 24 hours of soak time in the solution.

Red Arrow untreated door - Blue Arrow treated door

You can clearly see a dramatic difference in the color between the treated door and the original door.

The pictures were taken under my normal work bench lights and there has been no Photo-Shopping of the images.

After I took the pictures, the door was placed back in the solution with the face place and button assembly. The test will continue until Saturday, May 10th giving the items a total of 168 hours of soak time.

For this to be a viable process, the exact formula of the solution will have to be standardized and a proper method of testing the solution to determine if it's been depleted must be made.

It will also be necessary to test the process on every model of NuTone Master Station that was available in White or Bright White, to make sure that the process will work on all of the different plastics used.

These Models include: IM3003WH, IM4006WH, IMA4006WH, IM5006, IM3303WH, IMA3303WH, IM3204, IMA3204, IM4406, IMA4406.

It may also be possible to use this process on discolored and yellowed remote speakers, but I will leave that until I have the Master Station testing completed.

I think that this process will allow more homeowners to keep their original NuTone Radio Intercom Systems and not have to live with an unsightly Master Station


I will post more pictures after the ongoing test is completed. The next Master Station that will be tested is a IM5006.






A Picture is Truly worth a Thousand Words

NuTone Press Photograph September 17, 1960


Packing Your Intercom for Shipment

Whenever I talk with a customer about sending their Master Station in for repair, the final part of the conversation is about packing up their Master Station for shipment.  

Every Master Station needs to be protected against damage during shipment, otherwise it will end up like this IM5006.

This IM5006 was put into a box that was only slightly larger than the IM5006 itself and during shipment the box was probably dropped or bashed into something and the corner of the faceplate was broken.

When we package a Master Station for shipment, we do the following:

1.  The Master Station is placed inside a large plastic bag which is taped shut.  This prevents scuffs on the faceplate and prevents the styrofoam peanuts from getting inside the unit.

2.  We use extra heavy-duty Bubble Wrap (with large 1" bubbles) and wrap the Master in 3 layers of bubble wrap.  The first layer goes around the unit length-wise,  the 2nd and 3rd layers are wrapped around front to back.  All of the seams are taped closed to create a bubble wrap envelope.

3.  We use a new shipping box which measures 29" x 17" x 9".  This is the largest box which can be shipped based on its weight only and there is no additional charge for its "dimensional weight".

The other advantage to this size of box is that there is plenty of extra space around the Master Station in case the box is dropped or bashed into something.  Most shipping companies recommend a minimum of 4" of extra spaced around the contents of the box to prevent damage.

A layer of styrofoampPeanuts is placed in the box, the bubble-wrapped Master in placed on the peanuts and all of the extra space is filled with more peanuts.  The peanuts should be compacted somewhat to prevent the master from shifting around in the box.


4.  The box is sealed with lots of tape.  We tape the box with 3 rows of tape length wise, 5 rows of tape across its width and we seal the folded seams also.  This is done on both the top and bottom of the box.

Now the Master Station is ready to be shipped.  We use Fedex and each package is insured and will require a signature for delivery.


Repairing Intercoms requires a Global Effort

Most people have no idea how much work goes into having the necessary parts to repair NuTone intercoms systems.

Sourcing the correct components for several dozen different models that have been manufactured over the past 50 years is no small task. 

The biggest problem is part obsolescence.  Electronic components that were commonly available just 15 years ago are now becoming difficult to find and much more expensive to buy.  Many times we have to order hard to find parts from speciality suppliers in the US and from around the world. 

Components that were used in models that were manufactured in the mid 1990's through the mid 2000's are still available, but not always from suppliers located in the USA.

For these models our best source for components is in Asia.  After all that is where the components are manufactured and the products are assembled.

We work with a supplier in Singapore to source genuine replacement parts for many NuTone Intercom models.  What is truly amazing about this relationship is how easy and how fast it all works.

I placed an order with our supplier in Singapore on a Friday afternoon and the package with my parts was delivered on the following Tuesday.

We certainly live in great times. . .




Adding an Audio Jack to your NuTone Music Intercom Master Station

One of the most common and useful additions to any NuTone Music Intercom Master Station is a modern 1/8" (3.5mm) Audio Jack.  

The 1/8" audio jack is the most common size used today for modern audio devices. It looks just like the ear bud jack on your MP3 player of smart phone.  

When this type of jack is mounted to your NuTone Intercom master station, you can connect almost any type of external music source to play throughout your music intercom system.  This includes portable or table-top CD players, and almost all MP3 players including iPods and iPads.  You can also connect your smart phone to the system.

There are a few considerations to make this type of connection work correctly.  All of the modern devices I mentioned are Stereo Music Devices (they all have both right and left channel audio). Your NuTone Music Intercom System is a Mono System (the right and left channel audio are combined into one channel).

To have both channels of your stereo source play through the intercom system together, the audio jack has to be wired to mix the channels inside the jack.  There isn't any off-the-shelf kit that will have this setup, but it's easy to make from commonly available parts.

I sourced all of the parts from my local Radio Shack (every town has a Radio Shack) and the drill bit from my local Home Depot (again, everyone goes to Home Depot).

You will need two items from Radio Shack:

1)  1/8: Stereo Panel Mount Audio Jack  Model 274-249

1)  6-Ft. Shielded Cable, RCA Plug to Tinned Wires  Model 42-2371

And from Home Depot (or another hardware store):

1)  Irwin High Speed Steel Fractional Self-Starting UNIBIT  Model 10231.

To make up the Audio Jack and Cable, soldering is required.  For those of you who don't solder, ask a friend who does to help you.

The Audio Cable has two wires inside of it; the center wire is the Audio (positive) and the outer wire is the Ground (negative).

The Audio Jack has 3 connections on it (solder lugs); the 2 lugs on the back of the Jack are the Right and Left Channel (stereo) connections and the single lug at the top is the Ground (just one ground for both right and left channel is required).

(Red arrow is the Ground connection, Blue arrows are the Center wire connection, Yellow arrow is the RCS plug)

Turning the Stereo Jack into a Mono Jack is easy. Use the Center Wire in the Audio cable and solder it to the 2 lugs on the back of the jack (now right and left channels are mixed together). Then, solder the Outer wire from the cable to the single ground lug.  Your 1/8" jack is now complete and ready to be installed in the NuTone Master Station.

Now it's time to consider where on your NuTone Master Station the jack should be mounted.  I usually choose the side or the bottom of the Master Station's Faceplate to mount the jack.  

You will also need to look at the layout of the circuit boards on the back of the faceplate to find an area that has enough room to mount the jack easily.

The reason I choose to use the Irwin Unibit to drill the hole is because it will cut a very clean, round hole for the jack, it's easy to control the size of the hole and because conventional twist drill bits can grab the plastic of the faceplate and pull themselves in too fast.  This type of out-of-control drilling can cause the drill bit to hit a circuit board and RUIN IT (You have now been warned!)

Drill the hole, mount the 1/8" Audio Jack to the faceplate and plug the RCA Connector on the end of the Audio Cable into one of the Auxiliary Input connections on the back of the Intercom Master Station.

Most models have at least 2 inputs jacks to choose from. Select the AUX or TAPE jacks. Do not use the PHONO jack.

Now you are ready to listen to music from your own audio device.  Use a 1/8" to 1/8" Stereo Plug Cable (what ever length works best for your installation) to connect your music device (iPod) to the Master Station.

You might find that even with volume turned all the way up on your music device (iPod), the sound level from the Intercom System is lower than when you listen to the Radio.  This is typical for some music devices. Use the "System Volume" or "Program Volume" adjustment on your Master Station to compensate for the difference in volume.


If there is enough interest with our readers for this Audio Jack, I will consider offering it as a pre-made item for sale.

Please let me know what you think!

Use this Button to Contact Us about Ordering a Pre-Made Auxiliary Input Jack Assembly