Notes on the Troubleshooting and Repair of Computer and Video Monitors


  11.56) Fred's comments on monitor interference problems

(From: Fred Noble) Fred_Noble@msn.com)).

Monitors are very susceptible to electromagnetic fields. If any of the
following is "yes" it may point to an 'electrical' cause of the Monitor

* Do you have a ceiling fan in the same room turned on?
* Do you have a wireless telephone in the room?
* Do you get similar effects on your TV?
* Are you near a large transformer, substation, or high voltage overhead wires?
* Is your computer located close to the meter on the other side of the wall?
* Do you have speakers next to the monitor? Are they shielded?
* Do you have a phone or other device with a magnet in it near the monitor?
* Is the cabling routed too near a printer cable?
* Do you have a surge/power strip or UPS near your monitor?

Reposition the monitor or move it to a different location. Also make sure that
you are turning the monitor on first and then the system to ensure that the
video card is properly recognizing the monitor.

Check cable connections (make sure no other cables are crossing the monitor
cable. If you have an extension on the monitor output cable then remove it as

Try swapping out the monitor to verify if it really is the monitor or take
your monitor to another system and see how it responds there.

If you are plugging the monitor into a surge strip, remove it from there and
plug the monitor directly in the wall outlet.


There might be an ambient RFI/EMI electrical or magnetic field present around
your computer location.  Some of the electrical field or the conducted RFI/EMI
electrical "noise" causes are considered here.

Rough summary of excessive magnetic & electric fields:

* Cause: Electrical wiring errors.

  Electrical wiring errors such as inappropriate or non-NEC code neutral
  to ground bonds in the facility (not at the common bus in the mains), and
  other non-NEC Code wiring that results in the HOT wire fields not being
  OFFSET by the neutral wire fields.

  Incorrect wiring will be aggravated (and will be noticed first) on a circuit
  where there is an Air Conditioner, copier, laser printer.

  Correction: This is an electrical problem that has resulted in a *net
  current* flowing in the facility and is also a shock hazard.

  Don't use devices that dump current onto the neutral line, and have an
  electrician correct the wiring to NEC code.

* Cause: Magnetic flux linkages.

  It is normal for transformers to use magnetic flux linkages (to couple
  primary to the secondary).

  Correction: Keep transformer based equipment away from sensitive equipment.

  There are other corrective measures here that can be discussed on the design
  level and on the application level.

  If the transformer is used to power a "noisy" load (high harmonics) perhaps
  a good harmonic filter can be used between the transformer and the load
  (example a good UL 1283 noise filter or Surge suppressor with UL 1283

* Cause: Motors also use magnetic flux linkages in normal usage.

  Correction: Keep large, active, motors away from sensitive equipment (and
  try to keep them on a different circuit if possible).

  The use of a good harmonic filter on that circuit will help reduce the
  harmonics (for example, a good surge suppressor with a UL 1283 RFI/EMI
  filter, or a Line Conditioner).

* Cause: UPSs, especially when on inverter (during brownout or blackout)
  create magnetic & electric fields.

  Correction: Keep them away from sensitive loads, and advise manufacturer of
  problems encountered with the UPS.

  The UPS may have a faulty inverter circuit or part, or may be in need of a

  11.57) Loss of color after warmup

If there is a general loss of picture but there is light on the screen
if the brightness is turned all the way up, then this is a video input,
video amplifier, RGB driver, or power supply problem.

If it recovers after being off for a while, then you need to try a cold
spray in the video/controller to identify the component that is failing.
Take appropriate safety precautions while working in there!

If it stays broken, then most likely some component in the video circuitry,
controller, or its power supply as failed. There is a good chance that
it is a bad colder connection - the trick is to locate it!

Chapter 12) Miscellaneous Problems

  12.1) Contour lines on high resolution monitors - Moire

These fall into the category of wavey lines, contour lines, or light and dark
bands even in areas of constant brightness.  These may be almost as fine
as the dot pitch on the CRT or 1 or 2 cm or larger and changing across the
screen.  If they are more or less fixed on the screen and stable, then
they are not likely to be outside interference or internal power supply
problems.  (However, if the patterns are locked to the image, then there
could be a problem with the video board.)

One cause of these lines is moire (interference patterns) between the
raster and the dot structure of the CRT.  Ironically, the better the focus
on the tube, the worse this is likely to be.  Trinitrons, which do not
have a vertical dot structure should be immune to interference of this sort
from the raster lines (but not from the horizontal pixel structure).

You can test for moire by slowly adjusting the vertical size.  If it is moire,
you should see the pattern change in location and spatial frequency as slight
changes are made to size.  Changes to vertical position will move the patterns
without altering their structure - but they will not remain locked to
the moving image.

If they are due to the raster line structure - your focus is too good - the
patterns will remain essentially fixed in position on the face of the CRT
for horizontal size and position adjustments - the patterns will remain
fixed under the changing image.

How to eliminate it?  If moire is your problem, then there may be no easy
answer.  For a given resolution and size, it will either be a problem or
not.  You can try changing size and resolution - moire is a function
of geometry.  Ironically, I have a monitor which is nicer in this respect
at 1024x768 interlaced than at 800x600 non-interlaced.

Some monitors have a 'Moire Reduction Mode' switch, control, or mode.  This
may or may not be of help.  One way to do this is - you guessed it - is to
reduce the sharpness of the beam spot and make the picture fuzzier!  Another
approach adds a high frequency dither to the beam spot position which may
result in a headache!  You might find these cures to be worse than the

Another cause of similar problems is bad video cable termination
creating reflections and ghosting which under certain conditions can be so
severe as to mimic Moire effects.  This is unlikely to occur in all colors
with a VGA display since the termination is internal to the monitor and
individual resistors are used for each color (RGB).

I think it is ironic that some people will end up returning otherwise superb
monitors because of moire - when in many cases this is an indication of most
excellent focus - something many people strive for!  You can always get rid of
it - the converse is not necessarily true!

  12.2) Moire and shadow mask dot pitch

(From: Bob Myers (myers@fc.hp.com)).

The density of the holes in the shadow mask set an upper limit on the
resolution supported by that monitor.  Lower resolutions work just fine;
there is no need to have the logical pixels in the image line up with the
physical holes in the mask (nor is there any mechanism to make this happen),
and so you can think of this as the "larger pixels" of the lower-res image
simply covering more than one hole or slot in the mask.

As the effective size of the pixels in the image approach the spacing of
the mask holes, individual pixels are no longer guaranteed to cover enough
phosphor dots on the screen to ensure that they are constant color or constant
luminance, but an image will still be displayed which ON AVERAGE (over a
reasonably large area) looks OK.  Actually, the specified "top end"
format ("resolution") for most monitors usually is at or slightly beyond
this point - the effective pixel size is somewhat UNDER the dot pitch.

  12.3) Interference between monitor and VCR or TV

"I've got a desktop computer with a VGA monitor above it.  To the left of
 it (a few inches away), I have a VCR with a Commodore composite monitor
 above it (1084 model).  I don't have Cable TV or anything special, just a
 simple antenna connected to the VCR to pick up the two local TV stations.

 The reception is pretty good with the computer off, but the problem arises
 when I turn the computer on.  The VCR is already plugged into a different
 outlet than the computer.  Since I am into video production, I need this
 setup as it is laid out (close together).

 So, how can I shield the VCR from the interference from the computer?  Can
 I do something with the antenna to make the signal stronger, or can I
 place some kind of material between the VCR and computer?"

Your PC is a serious RF emitter.  Areas of leakage include the case as well
as the possibly the monitor and cable.  Turn off the monitor and/or unplug
the video cable to see if it is the latter.

You PC's case may not have adequate shielding. Better cases have grounding
fingers and proper RF shielding throughout - that is one reason they are
more expensive.  This may be an option.

The VCR may be picking up the interference internally or via its antenna.

There may be some options but you first need to determine where the
interference is coming from and where it is being picked up.

  12.4) Cable installed upside-down - now monitor does not sync correctly

"I have an old vga monitor that I screwed up.  I plugged it into the vga
card upside down.  Now I know that seems impossible, but believe me, it isn't.

Now the vertical is fine, but the horizontal is all screwy.  (is that a word? 
screwy?)  It's about 8" wide and can't be adjusted to normal size.

The result is a very, um, interesting image.  Is it possible that I did 
some minor damage like blowing a cap, diode, or horizontal transistor?"

I'll give you 100:1 odds that you bent the H sync pin and it is now bent over
and not inserted in its hole.  Remove the connector, and examine the pins - if
this is the case, take a pair of needlenose pliers and **very carefully**
straighten it out.  If it was pushed in, grab hold and pull it out to
the same length of the other pins and if necessary, put a drop of adhesive
at its base to prevent it from being pushed in again.  If it breaks off or
is unreachable, you will need to replace the connector (unless the shell
comes apart which is usually impossible or at least not easy on newer

  12.5) Isolated spots on display

These could be a problem with the video source - bad pixels in the video
card's frame buffer or bad spots on a camcorder's CCD, for example.
Or, they could be dirt or dead phosphor areas in the CRT.  Except for
problems with the on-screen character generator, it is unlikely that the
monitor's circuitry would be generating isolated spots.

You can easily distinguish between video problems and CRT problems - missing
pixels due to the video source will move on the screen as you change raster
position.  CRT defects will remain stationary relative to the screen and will
generally be much more sharply delineated as well.

There is a specification for the number and size of acceptable CRT blemishes
so you may have to whine a bit to convince the vendor to provide a replacement
monitor under warranty.

  12.6) Power saving problems

Modern monitors are usually designed to permit software to control
various levels of power saving ('green') features from blanking the screen
to totally shutting down.  Problems can occur if the software to control
these features is not compatible with the monitor or not set up
correctly or is attempting to control a monitor that lacks power saving
modes or is defective or incompatible.

A monitor that behaves normally under most conditions but emits a
high pitched whine when the computer attempts to direct it into power
saving mode is probably not understanding the commands or does not have
the appropriate power saving features.  It probably behaves about the
same as if there is no video signal - which indeed may be the case as
far as it is concerned.

Many monitors not receiving proper sync signals are perfectly happy
driving everyone in the office insane with that high pitched whine.
Others will blow up eventually.

Recommendation: don't use power saving until you have the proper software.
Of course, your monitor could be defective and your current software is
actually fine.  Check your user manuals to determine compatibility and
setup parameters.  Also see the sections: "Monitor life, energy conservation, and laziness" and "Implications of power saving modes".

  12.7) Monitor drift?

Problem: I have a 17" monitor that has an image that EVER SO SLIGHTLY drifts
to the left (and stops) after a long day's work (heat, I suppose).  Also, 
the vertical height shrinks a little bit.  Is this at all normal/acceptable?

How much is 'ever so slightly'?  There are a fair number of components whose
values could alter the position/size of a monitor image.  I do not find it
at all surprising that there should be a small shift due to heat.  It really
depends on many factors including the basic design, quality of components,
ventilation/cooling, etc.  Of course, it is possible to have a monitor that
has a component that is worse with respect to temperature.  Could also
be related to line voltage depending on the regulation of your monitor's
power supplies.

In general, my feeling is that if it is not objectionable (a 1/2" shift
would be objectionable) AND it's severity is not changing with time, you
can ignore it.

Many monitors do this.  TVs do this but you are not aware of it since they
are already 5-10% overscanned for just this reason, as well as compensating
for component aging and line voltage fluctuations.

A can of cold spray or a heat gun will be useful to track down the bad
component but it could be a frustrating search.

  12.8) Monitor shuts down or goes blank at certain scan rates

It could be the monitor's components have drifted and are now marginal
at your one or more of your scan rates.  However, first check with an
oscilloscope if possible to confirm that your horizontal and vertical
timing are indeed as expected.

Some video cards modify horizontal and vertical frequency as part of their
software size adjustment in their Setup program.  For example, with ATI
cards, even though the general resolution option in the DOS Install program
may be 800x600 at 75 Hz, adjusting the horizontal size can actually vary the
horizontal frequency over a greater than 10% range.  A similar variation
is possible with the vertical rate.

Does just the picture go away or does power die to the monitor?  If
you can see the neck of the CRT, the filaments glow orange when it is
operating.  Does this glow disappear indicating that the deflection/HV
is shutting down?

There could be a number of possibilities - no way of knowing if it
will be easy or inexpensive to repair without testing.  It could be
power supply, HV supply, X-ray protection, etc.

  12.9) Monitor flickers when disk accessed

This is almost certainly a software problem.  First, try moving the monitor
away from the PC as far as the cable will stretch.  If it still occurs,
then it is probably not the monitor.  Could have to do with power saving
(just a guess) or some other incompatibility.  Nothing the PC does should
affect the monitor in any way once the refresh rate is set.

  12.10) Buzzing monitor

Do you actually mean buzz - low frequency as in 50 - 120 Hz?  Or,
do you really mean high pitched whine.  If the latter, see the section:
"High pitched whine or squeal from monitor with no other symptoms".

The size of the monitor is not a strong indicator of the severity of the
problem but there will be some relationship as the power levels are higher for
larger sets.

* If it is from inside the monitor - make sure it is not your multimedia
  speakers or sound card picking up interference - it is in the deflection
  (probably vertical) or power supply.  Either of these can vary in severity
  with picture content due to the differing current requirements based on
  brightness.  It could be a power supply transformer, deflection yoke, or
  other magnetic component.  Even ferrite beads have been caught buzzing when
  no one was looking :-).  Any of these parts could vibrate if not anchored
  securely or as they loosen up with age.

  Some hot-melt glue, RTV silicone, or even a strategically wedged toothpick
  may help.  A new part may or may not quiet it down - the replacement could
  be worse!  For yoke noise, see the section: "Reducing/eliminating yoke noise".

* There is a slight possibility that the AC power in your home or office has
  some harmonic content - the waveform is not sinusoidal.  This might be the
  case if you try to run on the same circuit as an active dimmer or something
  else with thyristor control.  Proximity to heavy industry could also cause

  Relocating the offending device to another branch circuit may help.  You
  could also try a line conditioner (not just surge suppressor) which includes
  filtering.  Else, petition to have that paper manufacturer move out of the
  neighborhood :-).

* Sometimes, it is simply a design or manufacturing defect and the only
  alternative is a replacement - possibly a different brand.  It may be more
  difficult to quiet down a buzz than a high pitched whine.

* Some monitorss are simply poorly designed.  You cannot infer the severity of
  this annoyance from any specifications available to the consumer.  It is
  strictly a design (e.g. cost) issue.  The size of the monitor is not a
  strong indicator of the severity of the problem but there will be some
  relationship as the power levels are higher for larger units.  The best you
  can do is audition various monitors very carefully to find one that you are
  satisfied with.

* One those rare monitors that have a cooling fan, its bearings may be worn
  or in need of cleaning and lubrication, or a blade may be hitting something.

  12.11) High pitched whine or squeal from monitor with no other symptoms

Sometimes this is continuous.  In other cases, it comes and goes almost as
though there is an intelligence at work attempting to drive you crazy.  All
the more so since a technician may not even be able to hear what you are
complaining about if their hearing is not as sharp at high frequencies as
yours.  Even high resolution computer monitors running at high horizontal scan
rates (beyond human hearing) can have these problems due to the switching
power supplies as well as subharmonics of the horizontal scan rate exciting
mechanical resonances in the magnetic components.

If it is a new monitor and think the sounds will drive you insane, returning
it for a refund or replacement may be best alternative.  However, you may get
used to it in time.

Note: if the whine only occurs when the monitor is unplugged from the computer
or the computer is turned off, this is probably normal.  Without valid sync
signals the monitor defaults to a horizontal rate which is within the audible
range (less than 20 KHz).  Any vibrating components will be readily heard.
It is usually not a sign of impending failure.

In most cases, this sound, while annoying, does not indicate an impending
failure (at least not to the monitor - perhaps to your mental health) or
signify anything about the expected reliability of the set though this is not
always the case.  Intermittent or poor connections in the deflection or power
supply subsystems can also result in similar sounds.  However, it is more
likely that some part is just vibrating in response to a high frequency
electric current.

There are several parts inside the monitor that can potentially make this
noise - the horizontal flyback transformer and to a lesser extent, the
deflection yoke and associated geometry correction coils would be my first
candidates.  In addition, transformers or chokes in the switching power
supply if this is distinct from the horizontal deflection circuitry.

You have several options before resorting to a 12 pound hammer:

* As much as you would like to dunk the monitor in sound deadening insulation,
  this should be avoided as it will interfere with with proper cooling.
  However, the interior of the computer desk/cabinet can be lined with
  a non-flammable sound absorbing material, perhaps acoustic ceiling tiles.
  Hopefully, not a lot of sound energy is coming from the front of the monitor.

* Move the monitor out of a corner if that is where it is located - the corner
  will focus sound energy into the room.

* Anything soft like carpeting, drapes, etc. will do a good job of absorbing
  sound energy in this band.  Here is your justification for purchasing those
  antique Persian rugs you always wanted for your computer room :-).

If you are desperate and want to check the inside of the monitor:

* Using appropriate safety precautions, you can try prodding the various
  suspect parts (flyback, deflection yoke, other transformers, ferrite beads)
  with an insulated tool such as a dry wooden stick.  Listen through a
  cardboard tube to try to localizing the source.  If the sounds changes, you
  know what part to go after.  Sometimes a replacement flyback will
  cure the problem unless it is a design flaw.  You do not want to replace
  the yoke as convergence and other adjustments would need to be performed.
  Other transformers can be replaced.

* Sometimes, tightening some mounting screws or wedging a toothpick between
  the core and the mounting or coils will help.  Coating the offending part
  with sealer suitable for electronic equipment may quiet it down but too much
  may lead to overheating.  A dab of hot-melt glue or RTV silicone may help.
  Even replacement is no guarantee as the new part may be worse.  For yoke
  noise, see the section: "Reducing/eliminating yoke noise".

* A few monitors have internal cooling fans.  The whine may be due to worn or
  dry bearings.  If this is the case, the fan must be serviced as it is not
  likely doing it job and damage due to excessive temperatures may eventually
  be the result.

Note that the pitch of the whine - the frequency - may not even be audible
to a technician assigned to address your complaint.  The cutoff frequency
for our hearing drops as we get older.  Someone over 40 (men more so than
women), you may not be able to hear the whine at all (at least you can look
forward to silence in the future!).  So, even sending the monitor back for
repair may be hopeless if the technician cannot hear what you are complaining
about and you are not there to insist they get a second opinion!

  12.12) Monitor whines in power saving (standby) mode

(From: Bob Myers (myers@fc.hp.com)).

In standby, the monitor is not being supplied with horizontal sync, and
so the horizontal deflection circuits are free-running.  (If they're still 
powered up in a given monitor design when in standby mode, that is; there
are no standards governing what actually gets shut down in the various
power-saving states.)  It's likely that in this case, the horizontal is
free-running at a frequency which is audible, and you're hearing a whine
from a vibrating transformer core (for example, the flyback).  This will NOT
have anything to do with the timing used when the monitor is on and running
normally, so it's no surprise that changing the refresh rate didn't affect

You can either have a technician try to track down the offending component
and try to keep it from making the noise (usually by adding some "goop" to
prevent or at least reduce the audible effects of the vibration), or you
might try (if your system permits it) using one of the other power-management
states instead of standby.  Removing BOTH the horizontal and vertical 
sync signals places the monitor in the "off" condition (I'm assuming 
compliance to the VESA DPMS standard throughout this discussion), in which
just about everything should be shut down.  However, since this will remove
the heater supply from the CRT as well, it WILL take longer to recover from
the off state.

  12.13) Reducing/eliminating yoke noise

(From: Terry DeWick (dewickt@esper.com)).

Carefully look under vertical core next to plastic liner, on top and bottom is
a plate called the astigmatism shunt, it has come loose.  Work RTV, epoxy, or
service cement onto it to glue it down and noise should quit.

(From: TVman (tvman@newwave.net)).

I have fixed a total of 27 of these sets with noisy yokes by removing the
yokes and using motor armature spray sealant.

If you carefully mark the EXACT position of everything (yoke, purity magnets),
and slide the yoke off the CRT, then once the yoke has been sealed with motor
armature spray sealant and has dried thoroughly, put the yoke back EXACTLY
where it was, there should be no problems.

The only thing I have had to do was set the purity on one set, but it
was off a little to begin with.

  12.14) Monitor was rained on

Was the set plugged in when the leak started?  Any piece of equipment with
remote power-on capability has some portions live at all times when plugged
in and so there may have been damage due to short circuits etc.  Substantial
damage could have already been done.

Otherwise, you may just need to give it more time to dry out.  I have
had devices with keypads getting wet that required more than a week but
then were fine.   There are all kinds of places for water to be trapped and
take a long time to evaporate.

If the monitor got wet while unplugged or it has a mechanical (hard) on/off 
switch, then give it a lot of time to dry out completely.  Assuming all
visible water is drained, a week represents a minimum safe time to wait.
Don't rush it.

Generally, some moisture will not do any permanent damage unless the
set was on in which case you will simply have to troubleshoot it the
old-fashioned way - one problem at a time.

  12.15) Monitor was dropped

If your work area is maintained like that of Nedrie in the movie "Jurassic
Park, you might not even notice if one your monitors fell off the table!
This is no way to treat a monitor.

However, mishaps do happen.

Assuming it survived mostly intact - the CRT didn't implode, you could
still have a variety of problems.  Immediately unplug the monitor!

If you take it in for service, the estimate you get may make the national
debt look like pocket change in comparison.  Attempting to repair anything
that has been dropped is a very uncertain challenge - and since time is
money for a professional, spending an unknown amount of time on a single
repair is very risky.  There is no harm is getting an estimate (though
many shops charge for just agreeing that what you are holding was once
a - say - a monitor, or was it a fishtank?)

This doesn't mean you should not tackle it yourself.  There may be
nothing wrong or very minor problems that can easily be remedied.  The
following are likely possibilities:

1. Cracked circuit boards.  These can be repaired since monitors usually have
   fairly wide open single or two sided boards.

2. Broken circuit components.  These will need to be replaced.

3. Broken solder connections particularly to large heavy components
   on single sided boards.  Reflow the solder.  If the trace is cracked
   or lifted, repair as in (1).

4. Broken mounting brackets.  These are usually made of cheap plastic
   and often don't survive very well.  Be creative.  Obtaining an
   exact replacement is probably not worth the trouble and expense.

5. Components knocked out of line on the CRT envelope or neck  - deflection
   yoke, purity magnets, convergence magnets and coils, geometry correction
   magnets.  These will need to be reattached and/or realigned.  Some CRTs use
   little magnets glued to the funnel portion of the CRT envelope.  If any
   of these have come loose, it could be quite a treat to figure out where
   they went and in what orientation.

6. Internal damage to the CRT - popped or distorted shadow mask, misaligned
   electron guns.  Unfortunately, you will probably have no way of
   identifying these since you cannot see inside the CRT.  They will not
   be apparent until all other faults have been remedied and the TV set
   is completely realigned.  At that point, extremely severe purity or
   convergence problems that do not respond to the normal adjustment
   procedure would be one indication of internal damage.  Give the TV a
   nice funeral.

If you still want to tackle a restoration:

As noted, unplug the monitor even if it looks fine.  Until you do a thorough
internal inspection, there is no telling what may have been knocked
out of whack or broken.  Electrical parts may be shorting due to a broken
circuit board or one that has just popped free.  Don't be tempted
to apply power even if there are no obvious signs of damage - turning
it on may blow something due to a shorting circuit board.

Then, inspect the exterior for cracking, chipping, or dents.  In addition
to identifying cosmetic problems, this will help to locate possible areas to
check for internal damage once the covers are removed.

Next, remove the cover.  Confirm that the main filter capacitors are
fully discharged before touching anything.  Check for mechanical problems
like a bent or deformed brackets, cracked plastic parts, and anything that
may have shifted position or jumped from its mountings.  Inspect for loose
parts or pieces of parts  - save them all as some critical magnets, for
example, are just glued to the CRT and may have popped off.

Carefully straighten any bent metal parts.  Replace parts that were
knocked loose, glue and possibly reinforce cracked or broken plastic.
Plastics, in particular, are troublesome because most glues - even plastic
cement - do not work very well.  Using a splint (medical term) or sistering
(construction term) to reinforce a broken plastic part is often a good
idea.  Use multiple layers of Duco Cement or clear windshield sealer
and screws (sheetmetal or machine screws may be best depending on the
thickness and type of plastic).  Wood glue and Epoxy do not work well
on plastic.  Some brands of superglue, PVC pipe cement, or plastic hobby
cement may work depending on the type of plastic.

Inspect for any broken electronic components - these will need to be replaced.
Check for blown fuses - the initial impact may have shorted something
momentarily which then blew a fuse.

There is always a risk that the initial impact has already fried electronic
parts as a result of a momentary short or from broken circuit traces and
there will still be problems even after repairing the visible damage and/or
replacing the broken components.  This is most likely if the monitor was
actually on but some modern monitors have circuitry that is energized at
all times.  (If power is controlled by a tiny tiny pushbutton this is the

Examine the circuit boards for any visible breaks or cracks.  These will
be especially likely at the corners where the stress may have been greatest.
If you find **any** cracks, no matter how small in the circuit board, you
will need to carefully inspect to determine if any circuit traces run
across these cracks.  If they do, then there are certainly breaks in
the circuitry which will need to be repaired.  Circuit boards in consumer
equipment are almost never more than two layers so repair is possible but
if any substantial number of traces are broken, it will take time and patience.
Do not just run over them with solder as this will not last.  Use a fine
tipped low wattage soldering iron and run #22-26 gauge insulated wires
between convenient endpoints - these don't need to be directly on either
side of the break.  Double check each connection after soldering for correct
wiring and that there are no shorts before proceeding to the next.

If the circuit board is beyond hope or you do not feel you would be able
to repair it in finite time, replacements may be available but their cost
is likely to be more than the equipment is worth.  Locating a junk unit of the
same model to cannibalize for parts may be a more realistic option.

Degauss the monitor as any impact may magnetize the CRT.  Power cycling may
work but a manual degaussing is best.

Once all visible damage has been repaired and broken parts have been replaced,
power it up and see what happens.  Be prepared to pull the plug if there
are serious problems (billowing smoke or fireworks would qualify).

Perform any purity, convergence, or other realignment as needed.

Then proceed to address any remaining problems one at a time.

  12.16) Really cleaning a monitor inside and out

(From: Dr. Ludwig Steininger (drsteininger@t-online.de)).

Often I get defective monitors, which are more than 5 years old, and have been 
run in offices for 8 to 10 hours/day. So, their case and pcbs usually are very
dirty and dusty.

What do I do (it's no joke!): After removing the case I carefully put them in
a bath (on a flexible layer) and let them have a intensive shower of pure cold
water (for 1 to 2 minutes).  Additionally, the case is cleaned with soap or a
detergent containing liquid (being careful, not to spill to much of it onto
the PCBs). After rinsing with fresh clear water, dust and other kinds of dirt
are removed and the monitors look new again.  Then I allow all drops of water
to run off. This can effectively be supported by turning the monitor on
another side from time to time (duration: approximately 1 hour). Before
turning on AC again, I let the wet monitor dry in ambient air for about 2 days
(in the  sunshine this can be finished in 1 day only).

This procedure has been applied for many monitors. I've never had any bad 
experiences (it's very important to wait, until the pcbs are really dry!). 
Considering this experience, I just can't imagine, that it might not be 
possible, to "save" a TV set or computer monitor, which has been drowned or 
some liquid has been spilled, and AC has been plugged off ASAP (although I've 
never had such a case). I think, that in such a case, it's important to have a
rapid shower in order to prevent corrosion and deposits.

By the way: I know a German company, which uses water from cleaning PCBs of 
computer hardware for cleaning them after being contaminated by smoke from 
a fire.

So, in case of spillage, one has nothing to loose. Just try to shower your 
monitor or TV set!

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