Notes on the Troubleshooting and Repair of Small Household Appliances and Power Tools


  7.22) True (electronic) 3-way (or more) dimmers

The objective is to be able to control a single fixture from multiple locations
with the capability of dimming as well as just power on/off.

The simple type of 3-way dimmers are just a normal dimmer with a 3-way instead
of normal switch.  This allows dimming control from only one location.  The
other switches in the circuit must be conventional 3-way or 4-way type.

Connecting conventional dimmers in series - which is what such a hookup would
require - will not really work properly.  Only if one of the dimmers is set
for full brightness, will the other provide full range control.  Anywhere in
between will result in strange behavior.  The other dimmer may have a very
limited range or it may even result in oscillations - periodic or chaotic
variations in brightness.  The safety and reliability of such an arrangement
is also questionable.

True 3 way dimmers do exist but use a more sophisticated implementation
than just a normal dimmer and 3-way switch since this will not work with
electronic control of lamp brightness.  One approach is to have encoder knobs
(similar to those in a PC mouse) or up/down buttons at each location which
send pulses and direction info back to a central controller.  All actions
are then relative to the current brightness.  A low cost microcontroller or
custom IC could easily interface to a number, say up to 8 (a nice round
number) - of control positions.  The manufacturing costs of such a system
are quite low but due to its specialty nature, expect that your cost will
be substantially higher than for an equivalent non-dimmable installation.

If control of intensity at only one of the locations is acceptable, a
regular dimmer can be put in series with the common of one of the normal
3-way switches.  However, your brightness will be set by that dimmer alone.
See the section: "Typical dimmer schematics".

An alternative is to use X-10 technology to implement this sort of 
capability.  This would likely be more expensive than a dedicated
multi-way switch control but is more flexible as well.  X-10 transmits
control information over the AC lines to select and adjust multiple
addressable devices like lamps and appliances.

However, for the adventurous, see the section: "Independent dimming from two locations - kludge #3251".

  7.23) Independent dimming from two locations - kludge #3251

Here is a scheme which will permit dimming with independent control from two
locations.  Each location will have a normal switch and a dimmer knob.  The
toggle essentially selects local or remote but like normal 3-way switches, the
actual position depends on the corresponding setting of the other switch:

                 Location 1       Location 2
           +--------+  4-way SW    3-way SW
Hot o--+---| Dimmer |----o\ /o--------o\            +---------+
       |   +--------+      /            \o----------| Fixture |------o Neutral
       |              +--o/ \o--------o      Center +---------+ Shell
       |              |                      (brass)           (silver)
       |              |            +--------+
       |              +------------| Dimmer |--+
       |                           +--------+  |

As usual, the brass screw on the fixture or outlet should be connected to the
Hot side of the wiring and the silver screw to the Neutral side.

The dimmers can be any normal knob or slide type with an off position.

Note that as drawn, you need 4 wires between switch/dimmer locations.
4-way switches are basically interchange devices - the connections
are either an X as shown or straight across.  While not as common as
3-way switches, they are available in your favorite decorator colors.

If using Romex type cable in between the two locations, make sure to tape or
paint the ends of the white wires black to indicate that they may be Hot as
required by Code.

And, yes, such a scheme will meet Code if constructed using proper wiring

No, I will not extend this to more than 2 locations!

Also see the section: "Controlling a fixture or outlet from multiple locations".

CAUTION: However, note that a dimmer should not be wired to control an
outlet since it would be possible to plug a device into the outlet which
might be incompatible with the dimmer resulting in a safety or fire hazard.

  7.24) How do touch dimmers work?

(From: Neil).

Touch dimmers work in a couple of different ways, depending on the IC used.
Simple ones, such as those in the cheap 'touch lamps' that you find for sale
on market stalls, etc. normally have three or four preset brightness levels
and an OFF setting, which are operated sequentially: touch once for full
brightness, again to dim slightly, again to dim a bit more, etc, until the OFF
setting is reached. The next touch will then bring the lamp to full

The better (and more expensive) units, such as the touch dimmer switches that
are sold as direct replacements for conventional light switches, are similar,
but have many more steps. A single touch will usually bring the lamp to full
brightness, while keeping your finger in contact with the touch plate will
slowly dim the lamp. You just remove your finger when the lamp is at the
required brightness level.

Both kinds of touch dimmer have three basic parts;

1. A touch sensor - this normally works by picking up mains hum from the
   touch plate, and rectifying it in a high-gain amplifier.

2. A ramp generator - normally in the form of a digital counter with DAC

3. A mains power control element - Generally a thyristor or triac. In some
   designs, this is encapsulated within the IC, while in others it is a
   discrete component.

Most touch dimmers can be operated by standard push-button switches as well as
a touch plate, and many can be adapted for remote control.

There are a number of specially designed IC's available for touch dimmers,
notably the HT7704B ,a four-step device for touch lamps as described above,
and the SLB0586A, which is the other kind, with facilities for remote control.

  7.25) Light dimmers and interference with radio or TV

Due to the sharp edges on the power supplied by a cheap light dimmer, Radio
Frequency Interference (RFI) may be conducted back down the wiring directly to
other appliances and/or radiated through space as well.  Effects will include
noise bars in the picture on some TV channels and/or a buzz in the audio
across portions of the AM radio band.

Better light dimmers will include a bypass capacitor (e.g., .01 uF, 1KV)
and a series inductor to suppress RFI but these components were often left
off in basic models.  The FCC has tightened up on their regulations around
1992 so replacing older dimmer switches with newer ones may be the easiest

Installing in-line power line filters may work but other options like
replacing all your house wiring with metal conduit, or only listening to FM
radio are probably not realistic!

  7.26) Can I use a dimmer to control transformer operated low voltage lighting?

It is very tempting to try using a common light dimmer to control devices
using power transformers.  Will this work?

There really is no definitive answer.  It is generally not recommended
but that doesn't mean it won't work perfectly safely in many instances.

However, in principle this may be dependent on what is on the secondary
side - a transformer appears more inductive when it is lightly loaded - and
on the design of your particular dimmer.

It could blow the dimmer or result in the dimmer simply getting stuck at
full power for some or all of the control range since the inductive load
will cause the current to continue flowing even after the voltage has gone
to zero and the thyristor should shut off.  If it works reliably in your
situations, then this is not a problem.  Again, it may be load dependent.

It probably will result in more audible noise from the transformer but this
is probably harmless except to your sanity.

The only safety issues I can think of and these relate to the transformer
running hotter than normal as a result of core saturation.  This might
happen at certain settings if the thyristor is not switching at the same
point on the positive and negative half cycles.  There would be a net DC
current flow through the transformer which is not good,  If the thyristor
were to fail in such a way that it only triggered on one half cycle, very
large DC current could flow.  However, a suitably rated fuse or circuit
breaker and thermal cutout should handle both these situations.

Note: If your dimmer uses an SCR instead of a triac, this will result in
immediate and catastrophic failure. An SCR results in a DC output.  However,
full range dimmers usually use triacs.

The bottom line: I cannot provide any guarantees.

  7.27) Flashlights and lanterns

Battery operated flashlights (torches for those on the other side of the Lake)
and lanterns are among the simplest of appliances.  We probably all have a box
or drawer full of dead flashlights.

The most common problem after dead batteries is very often damage due to
leaky batteries.  Even supposedly leak-proof batteries can leak.  Batteries
also tend to be prone to leaking if they are weak or dead.  Therefore,
it is always a good idea to remove batteries from any device if it is not
to be used for a while.  How to assure the batteries will be with the
flashlight?  Put them in separate plastic bags closed and fastened with
a twist tie.

Test the batteries with a multimeter - fresh Alkalines should measure 1.5 V.
Any cell that measures less than about 1.2 V or so should be replaced as they
will let you down in the end.  On a battery tester, they should read well into
the green region.

Check the bulb with a multimeter on the ohms scale - a bad bulb will test
open.  Bulbs may fail from use just like any other incandescent lamp or
from a mechanical shock - particularly when lit and hot.  Replacement bulbs
must be exactly matched to the number and type of batteries (cells).  A
type number is usually stamped on the bulb itself.  There are special
halogen flashlight bulbs as well - I do not really know how much benefit
they provide.

The switches on cheap flashlights are, well, cheaply made and prone to
unreliable operation or total failure.  Sometimes, bending the moving
metal strip a bit so it makes better contact will help.

Clean the various contacts with fine sandpaper or a nail file.

If a flashlight has been damaged as a result of battery leakage, repair
may be virtually impossible.

High quality flashlights are another matter.  Maglights(tm) and similar
units with machined casings and proper switches should last a long time
but the same comments apply to batteries - store them separately to avoid
the possibility of damage from leakage.  Keep a spare bulb with each of
these - the specialty bulbs may be harder to find than those for common
garbage - sorry - flashlights.

Rechargeable flashlights include a NiCd or lead-acid battery (one or more
cells in series) and the recharging circuitry either as part of the unit
itself or as a plug-in wall adapter or charging stand.  See the sections:
"Battery chargers" and "Typical rechargeable flashlight schematics" for more

  7.28) Typical rechargeable flashlight schematics

Here are circuit diagrams from several inexpensive rechargeable flashlights.
These all use very 'low-tech' chargers so battery life may not be as long as
possible and energy is used at all times when plugged into an AC outlet.

  7.29) First Alert Series 50 rechargeable flashlight schematic

This one is typical of combined all-in-one units using a lead-acid battery
that extends a pair of prongs to directly plug into the wall socket for

It is a really simple, basic charger.  However, after first tracing out the
circuit, I figured only the engineers at First Alert knew what all the diodes
were for - or maybe not :-).  But after some reflection and rearrangement of
diodes, it all makes much more sense:  C1 limits the current from the AC line
to the bridge rectifier formed by D1 to D4.   The diode string, D5 to D8 (in
conjunction with D9) form a poor-man's zener to limit voltage across BT1 to
just over 2 V.

The Series 50 uses a sealed lead-acid battery that looks like a multi-cell
pack but probably is just a funny shaped single cell since its terminal voltage
is only 2 V.

Another model from First Alert, the Series 15 uses a very similar charging
circuit with a Gates Cyclon sealed lead-acid single cell battery, 2 V, 2.5
A-h, about the size of a normal Alkaline D-cell.

WARNING: Like many of these inexpensive rechargeable devices with built-in
charging circuitry, there is NO line isolation.  Therefore, all current
carrying parts of the circuit must be insulated from the user - don't go
opening up the case while it is plugged in!

                                             2V LB1  Light
                                           1.2A +--+ Bulb    S1
                                       +--------|/\|----------o/ o----+
            _ F1   R3         D3       |        +--+                  |
   AC o----- _----/\/\---+----|>|--+---|----------------------+       |
          Thermal  15    |    D2   |   |                 4A-h |       |
           Fuse          | +--|>|--+   |         BT1 - |+ 2V  |       |
                         | |  D4       +--------------||------|-------+
                         +----|<|--+   |               |      |       |
                           |  D1   |   |  D8   D7   D6   D5   |  D9   |
          |        |                                                  |
          |        /                                                  |
         _|_ C1    \ R1                                               |
         --- 2.2uf / 100K                                             |
          |  250V  \                                                  |
          |        |               R2          L1  LED                |
   AC o---+--------+--------------/\/\-----------|<|------------------+
                                 39K 1W       Charging

  7.30) Black & Decker Spotlighter Type 2 rechargeable flashlight

This uses a 3 cell (3.6 V) NiCd pack (about 1 A-h).  The charging circuit is
about as simple as it gets!

         11.2 VRMS                                +---------------o/ o----+
  AC o-----+ T1       R1      LED1         D1     |  +| | | -             |
            )|| +----/\/\-----|>|---->>----|>|----+---||||||---+          |
            )||(      33    Charging     1N4002       | | |    |  KPR139  |
            )||(      2W                           BT1         |    LB1   |
            )||(                                   3.6V, 1 A-h |    +--+  |
            )|| +-------------------->>------------------------+----|/\|--+
  AC o-----+                                             Light Bulb +--+

        |<------- Charger ---------->|<---------- Flashlight ----------->|

I could not open the transformer without dynamite but I made measurements of
open circuit voltage and short circuit current to determine the value of R1.
I assume that R1 is actually at least in part the effective series resistance
of the transformer itself.

Similar circuits are found in all sorts of inexpensive rechargeable devices.
These have no brains so they trickle charge continuously.  Aside from wasting
energy, this may not be good for the longevity of some types of batteries (but
that is another can of worms).

  7.31) Brand Unknown (Made in China) rechargeable flashlight schematic

This is another flashlight that uses NiCd batteries.  The charger is very
simple - a series capacitor to limit current followed by a bridge rectifier.

There is an added wrinkle which provides a blinking light option in addition
to the usual steady beam.  This will also activate automatically should there
be a power failure while the unit is charging if the switch is in the 'blink'

With S1 in the blink position, a simple transistor oscillator pulses the light
with the blink rate of about 1 Hz determined by C2 and R5.  Current through R6
keeps the light off if the unit is plugged into a live outlet.  (Q1 and Q2 are
equivalent to ECG159 and ECG123AP respectively.)

            R1          D1                 R3   LED1
    AC o---/\/\----+----|>|-------+---+---/\/\--|>|--+    D1-D5: 1N4002
            33    ~|    D2        |+  |   150        |
           1/2W    +----|<|----+  |   |       R4     |  D5
                        D3     |  |   +------/\/\----+--|>|--+
              C1   +----|>|----|--+   |    33, 1/2W          |   LB1 2.4V
            1.6uF ~|    D4     |      |   | |                |   +--+ .5A
    AC o--+---||---+----|<|----+--+---|--||||--------------+-+---|/\|----+
          |  250V  |              |-  | - | |+             |     +--+    |
          +--/\/\--+              |   |   BT1      + C2 -  |      R5     |
              R2                  |   |  2.4V    +---|(----|-----/\/\----+
             330K                 |   |          |  22uF   |     10K     |
                                  |   |    R6    |       |/ E            |
                                  |   +---/\/\---+-+-----| Q1            |
                                  |       15K      |     |\ C  +---------+
                                  |                /  C327 |   |         |
                                  |             R7 \   PNP |   |   1702N |
                                  |           100K /       |   |   NPN |/ C
                                  |                \       +---|-------| Q2
                                  |      On        |           |       |\ E
                                  |   S1 o---------|-----------+         |
                                  +----o->o Off    |                     |
                                    Blink/Power Fail

  7.32) Makeup mirrors

There are a simple movable mirror with incandescent or fluorescent lighting
built in.

Replacing incandescent light bulbs can usually be done without disassembly.
The bulbs may be of the specialty variety and expensive, however.

When a unit using fluorescent bulbs will no longer come on, the most likely
cause is a bad bulb.  However, replacement may involve disassembly to fain
access.  Where two bulbs are used, either one or both might be bad.  Sometimes
it will be obvious which is bad - one or both ends might be blackened.  If
this is not the case, replacement or substitution is the only sure test.  These
**will** be expensive $7-10 is not uncommon for an 8 inch fluorescent bulb!

Other possible problems: plug, cord, switch, light bulb sockets.

  7.33) Chandeliers

A chandelier is simply an incandescent light fixture with multiple sockets.
No matter how fancy and expensive, the wiring is usually very simple - all
the sockets are connected in parallel to a cord which passes through the
chain to a ceiling mounted electrical box.

If none of the lights come on, check for a blown fuse or circuit breaker,
bad wall switch or dimmer, a bad connection in the ceiling box or elsewhere
in the house wiring, or a bad connection where the cord is joined to the
individual socket wires.

Where only one bulb does not light - and it is not a burned out bulb - a
bad socket, loose wire connection at the socket, or bad connection at the
point where the wires are joined (Wire Nuts(tm) or crimps) is likely.

  7.34) Portable fans and blowers

These consist of a cordset, switch, and AC motor.  Oscillating fans add
a gearbox to automatically swivel the fan to direct air in more than one
direction.  Most are of the bladed variety though some small types might
use a squirrel cage type centrifugal blower.

There are two kinds of problems: totally dead or stuck/sluggish.

A totally dead fan can be the result of several possible causes:

* Bad cord or plug - these get abused.  Test or substitute.

* Bad power switch - bypass it and see if the fan starts working or test
  with a continuity checker or multimeter.  Sometimes, just jiggling it
  will confirm this by causing the fan to go on and off.

* Open thermal fuse in motor - overheating due to tight bearings or a motor
  problem may have blown this.  Inspect around motor windings for buried
  thermal fuse and test with continuity checker or multimeter.  Replacement
  are available.  For testing, this can be bypassed with care to see if the
  motor comes alive.

* Burned out motor - test across motor with a multimeter on the low ohms
  scale.  The resistance should be a few Ohms.  If over 1K, there is a
  break in the motor winding or an open thermal fuse.  If there is no fuse
  or the fuse is good, then the motor may be bad.  Carefully inspect for fine
  broken wires near the terminals as these can be repaired.  Otherwise, a
  new motor will be needed.  If the motor smells bad, no further investigation
  may be necessary!

* Bad wiring - check for broken wires and bad connections.

As always, your continuity checker or multimeter on the low ohms scale
is your best friend and can be used to trace the wiring from the wall plug
through all components of the appliance.

Sluggish operation can be due to gummed up lubrication in the motor or any
gears associated with an automatic oscillating mechanism.  Disassemble,
thoroughly clean, and then lubricate the motor bearings with electric motor
oil.  Use light grease for the gearbox but this is rarely a problem.

A noisy fan may be due to dry motor or other bearings or loose hardware
or sheetmetal.  Disassemble, clean, and lubricate the motor or gearbox
as above.  Inspect for loose covers or other vibrating parts - tighten
screws and/or wedge bits of wood or plastic into strategic locations to
quiet them down.  

Damaged fan blades will result in excessive vibration and noise.  These
may be easily replaceable.  They will be attached to the motor shaft with
either a large plastic 'nut' or a setscrew.  However, locating a suitable
set of blades may be difficult as many cheap fans are not made by well
known companies.

  7.35) Computer power supply (and other) fans

Virtually all of these use brushless DC motors with stationary coils and a
rotating multipole magnet which is part of the blade assembly.  Most common
problems are gummed up lubrication or worn bearings - especially for the cheap
sleeve bearing variety found in most PCs.  Occasionally, an electronic failure
will result in a dead spot or other problem.

Ball bearing fans rarely fail for mechanical reasons but if the bearings
become hard to turn or seize up, replacement will usually be needed.  (Yes,
I have disassembled ball bearings to clean and relube THEM but this used only
as a last resort.)

WARNING: For power supply fans, be aware that high voltages exist inside the
power supply case for some time (perhaps hours) after the unit is unplugged.
Take care around the BIG capacitors.  If in doubt about your abilities, leave
it to a professional or replace the entire power supply!

The only type of repair that makes sense is cleaning and lubrication.  Else,
just replace the fan or power supply.  It isn't worth troubleshooting
electronic problems in a fan!

If you want to try to clean and lubricate the bearings, the blade assembly
needs to be removed from the shaft.  There should be a little clip or split
washer holding it on.  This is located under a sticker or plastic plug on the
center of the rotating blade hub.  Once this fastener has been removed, the
blades will slide off (don't lose the various tiny spacers and washers!)

Thoroughly clean the shaft and inside the bushings and then add just a couple
drops of light oil.  Also, add a few drops of oil to any felt washers that may
be present as an oil reservoir.

Reassemble in reverse order making sure the tiny washers and spacer go back
in the proper positions.

How long this lasts is a crap shoot.  It could be minutes or years.

Replacement fans are readily available - even Radio Shack may have one that
is suitable.  Nearly all run on 12 VDC but some small CPU fans may use 5 VDC.
While current ratings may vary, this is rarely an issue as the power supply
has excess capacity.  Air flow rates may also vary depending on model but are
usually adequate for use in PCs.

  7.36) Speed control of DC fans

The small fans used in computers and peripherals usually run on 5, 12 (most
common) or 24 VDC.  Most of the time, their speed and air flow are fine for
the application.  However, is it possible to vary it should the need arise?

Usually, the answer is a qualified 'yes'.  Except for some that are internally
regulated or thermostatically controlled, the speed is affected by input
voltage.  It is likely that the fan will run on anywhere from .5 to 1.25 times
the nominal input voltage though starting when it is near the low end of this
range may need some assistance.

A universal DC wall adapter, adjustable voltage regulator, or (variable)
series power resistor can provide this control.  For example:

                     25, 2 W        + +--------+ -
    +12 VDC o-----+---/\/\---+--------| DC FAN |----o Gnd
                  |   +      |        +--------+
                  +----|(----+      12 VDC, .25 A
                    10,000 uF
                      25 V

The 25 ohms power resistor should reduce the speed of this fan by about 25 to
30 percent.  The capacitor provides full voltage for a fraction of a second to
assure reliable starting.

  7.37) Speed control of small AC fans

The following comments should also apply to many other types of appliances
using small AC motors.

These small shaded pole fans will work just fine on a Variac.  Any speed you
want, no overheating, etc.  I had done this with all sorts of little computer
cooling fans as well as larger (remember those old DEC PDP-11 rack fans?).

Small triac based speed controls like those used for ceiling fans may also
work.  Even light dimmers will *probably* work for medium size fans or banks
of fans though I cannot guarantee the reliability or safety of these.  The
problem is that small induction motors represent a highly inductive loads for
the light dimmer circuitry which is designed for a resistive load.  I have
achieved a full range of speeds but over only about 1/4 to 1/2 of the rotation
of the control knob.  There is some buzz or hum due to the chopped waveform.

However, from my experiments, light dimmers may have problems driving a single
small fan.  If the load is too small, the result may be a peak in speed (but
still way less than normal) at an intermediate position and the speed actually
much lower when on full, or reduced speed even on full.  In this case, adding
a resistive load in parallel with the motor - a light bulb for example - may
improve its range.  It adds a sort of quaint look as well! :-)

If you do opt for a solid state speed control, make sure you include a fuse
in the circuit.  A partial failure of the triac can put DC through the motor
which would result in a melt-down, lots of smoke, or worse.

The reason these simple approaches will work for these AC motors is that they
are high slip to begin with and will therefore have a high range of speed vs.
input voltage.  The only concern is overheating at some range of lower speeds
due to reduced air flow.  However, since these fans are normally protected even
against stall conditions, I wouldn't expect overheating to be a problem - but
confirm this before putting such fans into continuous service.

If all you need to do is provide a fixed, reduced speed for a bank of similar
AC fans, try rewiring them as two sets of parallel connected fans in series.
The result will be 1/2 the normal line voltage on each fan motor which may
provide exactly the speed you want!  The extension to more than 2 sets of fans
is left as an exercise for the student :-).

  7.38) Ceiling fans

While the original slow rotating ceiling mounted fan predates the widespread
use of airconditioning, there is a lot to be said for the efficiency,
effectiveness, and silence of this technology - not to mention the ambiance.

A ceiling fan is just an induction motor driving a set of blades.  Multiple
taps on the motor windings in conjunction with a selector switch provides
speed control for most inexpensive fans.  Better units include a solid state
motor speed control.

The light often included with the fan unit is usually just an incandescent
fixture with 1-5 bulbs and a switch.  This may be a simple on-off type,
a selector to turn on various combinations of bulbs, or a dimmer with
continuous or discrete control of illumination.

WARNING:  Always check mechanical integrity of fan mounting when installing
or servicing a ceiling fan.  Original design and construction is not always 
as fail-safe as one might assume.  Double check for loose nuts or other
hardware, adequate number of threads holding fan to mounting, etc.  These
have fallen without warning.  Only mount in ceiling boxes firmly anchored
to joists - not just hanging from the ceiling drywall!  Check that the
fan is tight periodically.  The constant vibration when running, slight as
it is, can gradually loosen the mounting hardware.  Furthermore, if pull
chain type switches are used for the fan or light, constant tugging can also
tend to loosen the entire fan.

Failures of ceiling fans can be divided into electrical and mechanical:


* No power - Use a circuit tester to determine if power is reaching the
  fan.  Check the fuse or circuit breaker, wall switch if any, and wire
  connections in ceiling box.

* Bad switch in fan - with power off, check with a continuity tester.  If
  wiring is obvious, bypass the switch and see if the fan comes alive.
  Jiggle the switch with power on to see if it is intermittent.  For
  multispeed fans, exact replacements may be required.  For single speed
  fans, switches should be readily available at hardware stores, home
  centers, or electrical supply houses.

* Bad or reduced value motor start/run capacitor.  This might result in
  slower than normal speed or lack of power, a fan that might only start
  if given some help, or one that will not run at all.

  For an existing installation that suddenly stopped working, a bad cap is
  a likely possibility.  An induction motor that will not start but will
  run once started by hand usually indicates a loss of power to the starting
  (phase) winding which could be an open or reduced value capacitor.

  This is probably a capacitor-run type of motor where the capacitor provides
  additional torque while running as well.  Therefore, even starting it
  by hand with the blades attached might not work.  With the blades removed,
  it would probably continue to run.  Of course, this isn't terribly useful!

* Bad motor - if all speeds are dead, this would imply a bad connection
  or burned winding common to all speeds.  There might be an open thermal
  fuse - examine in and around the motor windings.  A charred smelly
  motor may not require further testing.  A partially shorted motor may
  blow a fuse or trip a circuit breaker as well or result in a loud hum
  and no or slow operation as well.


* Noise and/or vibration - check that fan blades are tight and that any
  balance weights have not fallen off.  Check for worn or dry bearings.
  Check for sheetmetal parts that is loose or vibrating against other parts.
  Tighten screws and/or wedge bits of plastic or wood into strategic spots
  to quiet it down.  However, this may be a symptom of an unbalanced fan,
  loose fan blade, or electrical problems as well.  Check that no part of
  the rotating blade assembly is scraping due to a loose or dislodged

* Sluggish operation - blades should turn perfectly freely with power off.
  If this is not the case, the bearings are gummed up or otherwise defective.
  Something may be loose and contacting the casing.  (This would probably
  make a scraping noise as well, however).

  7.39) Lubricating ceiling fans

(From: Chris Chubb (cchubb@ida.org)).

I use synthetic transmission lube, 80-130 (manual gearbox, not automatic
transmission fluid which is very thin --- sam).  I imagine that any similar
lubricant, synthetic or not, would work as well, but the synthetic flows down
in better and works well.

Do not use WD-40, 3-in-1 oil or any other lightweight oil. Motor oil is good
as well, but it does not stick to the bearings as well.  DO NOT use automatic
transmission fluid - extremely thin.

Grease would be perfect, white lithium, divine!  But, getting the grease
down into the bearings would be very difficult.

Just about three or four drops should be all it takes. Getting it
on the lower bearings of the ceiling fan will be tough. I have an
oil can that I pump a drop to the tip of, then hold it against the 
bearings until they wick the oil inside. This is very slow. It takes
about 15 minutes per fan to oil, clean the top of the blades, oil
a little around the hanging ball, pull the globe off and clean 
the globe inside, and make sure everything is OK. 

  7.40) Variable speed ceiling fan on normal circuit

It is usually not possible to use a normal light dimmer to control the fan
as this uses an AC induction motor.  A dimmer can only be used on the built
in light if a separate wire is available to power it.

Doing this will likely result in a nasty hum or buzz at anything other than
full brightness (speed) or off.  This is both annoying and probably not good
for the fan motor as well.  A dimmer works by reducing the power to the
light by controlling when the voltage is applied on each cycle of the AC.  If
it is turned on half way through the cycle half the power is provided, for
example.  However, with cheap lamp dimmers, this results in sharp edges on
the waveform rather as peak voltage is applied suddenly rather than with the
nice smooth sinusoid.  It is these sharp edges causing the coils or other
parts of the fan to vibrate at 120 Hz that you are hearing.

Special speed controls designed for ceiling fans are available - check your
local home center or ceiling fan supplier.

Here is another alternative:

(From: Rick & Andrea Lang (rglang@radix.net)).

Here's a potential solution if you don't mind spending a little more for 
a ceiling fan (If you already have one in that location, perhaps you can put
it in another room).  Ceiling fans with remote control are now available. 
They only require power to the ceiling fan (2 wire) and a remote 
control. With the remote you can dim the lights, slow the fan or both. 
You can then use the existing new wall switch as a power ON/OFF switch 
also. If you choose this route, be careful of interference with garage 
door openers. Usually, the remotes have at least 4 frequency selections 
to help avoid interference with other remote systems. I put one in that 
three of the four frequencies opened the garage door. I lucked out on
the 4th one!

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