Northside Service Company

NuTone LB42 chime base

The original NuTone 8 note Westminster Chimes were models that began with the letter "K" then came the "L" series followed by "LA" then "LB".

This is the base from a model LB42, Long Tube Westmentser Chime.  It was made in 1975 and the owner reported that it hasn't worked in years.

Lets see why it won't work. . . 

NuTone LB42 chime base motor

All NuTone 8 note chime bases used small electrical motor through 1990.  After 19909 the clock motor design was replaced with an electronic control board.

These little clock motors are vary rarely the problem with a chime like this LB42

NuTone LB42 chime base terminals with arrow

The right hand side of the chime base has the screw terminals where all of the wires connect.

The LB42 has the capacity of 3 entry doors, Front, Rear and Side.  Each door will ring a different note.

The blue arrow points to the volume adjustment knob.  This adjusts how hard (or soft) the plungers will strike the tubes.

NuTone LB42 clock motor removed from chime base

The clock motor is easy to remove from the chime base, it's held in place by 4 screws.

Care needs to be taken with the motor, since it is no longer available to purchase from NuTone.

NuTone LB42 chime base reverse side of motor wiper arms with arrows.

On the back of the clock motor is the 3 arm wiper assembly.

The blue arrows point to the contact oints on the ends of each arm.

As the clock motor turns (slowly) it turns the wiper arm and the contact point make connections on the circuit board.  This is how the chime rings the tubes in the proper sequence.  

NuTone LB42 wiper arm assembly removed for drive gear

Here you can see how the 3 arm assembly fit to the gear on the back of the clock motor

NuTone LB42 chime base start stop lever

The blue arrow points to a small but very important part of the chime base, the "start - stop" lever.

This thin, springy piece of metal regulates the starting and stopping of the clock motor when someone pushed an entry door pushbutton.

This lever can and does break due to age.  If it's broken the chime will not work correctly.  It is oftem possible to solder the lever together if all of the pieces are found.

NuTone LB42 chime base dirty traces with arrows

Under the clock motor is the circuit board which has the circuit traces, where the wiper arm contacts make and break the connections for the ring sequence.

These traces become dirty and covered with carbon after years of use.  This can cause the chime to ring intermittently or stop ringing mid sequence.

NuTone LB42 dirty traces with pencil.

The very best way to clean the circuit traces is to simply use a pencil eraser.  Anything harsher than the eraser may damage the traces.

NuTone LB42 circuit board half cleaned

The blue arrow points to the first half of the cleaned board.

NuTone LB42 circuit board fully cleaned

Here the circuit board has been fully cleaned and it is ready to have the clock motor reattached.

NuTone LB42 chime base reverse side with arrows

On the back side of the chime base, the blue arrows point to wire that connect the plunger solenoids to the circuit board.

These are vary small wires and they can easialy be damaged, cauction here is a good idea.

NuTone LB42 chime base plunger assemblies

Here are the solenoid plunger assemblies on the chime base.  These are often the source of a non functioning chime.  

It's not that the soleniods fail, they almost never do.  Non operation is usually caused by time and age and also by well meaning homeowners spraying lubricants into the solenoids.

On very early chimes NuTone used a natural rubber cushion inside the back of the solenoid tube.  Over time this natural rubber will degrade and become sticky, causing the plunger to become stuck inside the solenoid.

nuTone LB42 plungers and springs

Here are the 4 plungers and the 4 return springs.  Be sure not to lose the springs when the plungers are removed.  They are necessary to make the chime ring correctly and of course they are no longer available.

You can see the black gunk onthe end of the plungers (blue arrows) this is whatreamins of the foam cushion that was originally inside the soleniod tube. 

Since this is a mid-70's chime, the cushion was made from a cellular foam material, which was probably dissolved  when someone spray WD40 into the solenoids.

NuTone LB42 gunked up plungers with box and arrow

Another view of the gunked up plungers.  These plungers were so stuck inside the solenoid tubes and I had to use a drift and a small hammer to carefully drive them out.

The best way to clean the goo off the plungers is to a razor blade to cut and scrape the base of the plungers as clean as you can.  Then use some lighter fluid (the kind for a Zippo) and clean away the remaining goo.

I don;t soak the plungers in the lighter fluid because I don't want to take the chance that it will affect the plastic tips on the plunges.

nuTone LB42 plunger caps

These are the 4 solenoid end caps.  You can see the hardened gunk inside the caps.  It's best to leave these as they are because they can easily crack and fall into pieces due to their age.

NuTone LB42 gunked up plungers with boxes

This is how this looked when the end caps were removed.  Notice how the foam has built up inside the tube

NuTone LB42 solenoid bore

With the plungers removed, you have just a brass tube with stick goo inside of it.  These need to be cleaned completely otherwise the plungers will get stuck again.

NuTone LB42 cleaning chime bores

The best way to clean the solenoid tubes is to stuff the full of paper towels and soak the towels with lighter fluid.

Use the kind of lighter fluid that goes into Zippo or other types of lighters, do not use BBQ lighter fluid or any type of solvent.

Once the goo has been softened up with the lighter fluid, use a small brush or a cloth on the end of a small diameter rod to clean inside the tube.  You must be careful not to gouge the tube when you clean it.

In the very worst cases you can use some 600 or 800 grit wet sand paper.  DO NOT USE anything sand paper less than 600 grit.  It will score the brass tubes, causing added resistance to the plungers and they will not ring properly.

After everyting has been cleaned, place the spring into the tube, followed by the plunger and the place the end cap on the tube.

The plunger should slide freely inside the tube, if it does not, it was not cleaned well enough.

Nuone LB42 chime base with repair supplies

Here is the rebuild chime base along side everything you will need to clean it.

1.  Lighter fluid

2.  Small bristle brush

3.  Small cleaning swab

4.  Textured cleaning paper cloth

5.  600 grit wet sandpaper.

The total amount of time it took to clean and rebuild this chime base was 30 minuets.