Notes on the Troubleshooting and Repair of Video Cassette Recorders


  12.10) Rainbow pattern in recordings made over previously recorded tapes

Unless your VCR has a flying erase head - located along with the normal
video heads on the rotating drum - you will see a faint rainbow pattern near
the start when recording over a previously used tape.  The reason is that there
is a separation of a few inches in the tape path between the video heads
and the full width erase head.  When you start recording at an arbitrary
point, it takes several seconds (actual time depends on recording speed)
totally erased tape to make it to the video heads.  You are seeing
an interference pattern between the old and new video signals.  The pattern
will slowly wipe from top to bottom as the diagonal tracks of new video
intersect more and more of the erased tape.

This effect will not occur (except possibly at the very beginning of the
tape) as long as you record from start to end without backing up the tape
at any time.

If the rainbow pattern is present whenever recording over previously
recorded tapes and does not go away, then your full width erase head
is not working.  This could be due to an electronic failure or simply a bad 
connection to the full width erase head.  Alternatively, a mechanical
problem such as a broken or popped spring or gummed up lubrication might
prevent the pivoting full width erase head from contacting the tape properly.  

  12.11) Barber poling - bands of rainbow or color

Some rainbow patterns are normal for the first few seconds of recordings
made on previously recorded tapes on non-flying erase head VCRs.  See the
section: "Rainbow pattern in recordings made over previously recorded tapes".
However, alternating bands of rainbow or color indicate a fault sometimes
referred to as 'barber poling'.

This  is likely an electrical fault in the chroma playback circuitry buried
deep in the bowels of your VCR.  The chroma reference is not locking or is
locking erratically with the chroma signal.  Unless you can find some bad
connections or other obvious problem, this will be difficult to troubleshoot
without schematics.  Don't be tempted to twiddle internal controls even if
they appear to deal with color - you will just mess things up for whoever
finally repairs your VCR!

  12.12) Flag waving - top portion of picture wiggling back and forth

You have just loaded a videotape sent to you from your long lost cousin and
you notice that the top of the picture is wiggling back and forth.

First, if this wasn't the original complaint, make sure the flag waving
problem exists with the TV that will actually be used with the VCR - it
may just be your test TV or monitor that is unhappy.

(Parts of the following from: Andrew Morphitis, Andrew@andrewsm.demon.co.uk).

This fault is sometimes known as flag-waving when associated with video 
recorders. If the tape back-tension provided by the tension arm and 
supply reel-table is not the same as the back-tension provided when the 
tape was recorded (possibly on another machine) then the field timing of 
the video tracks being played back will be inconsistent . Your back- 
tension can be checked using a back-tension cassette gauge (a typical 
reading would be about 35g-cm for VHS) or you could adjust the back 
tension using a known good test tape (or reliable pre-recorded tape) 
until the waving disappears. If your back-tension does turn out to be 
incorrect and you adjust it according to the manufacturers spec. then 
all of the tapes you have previously recorded will probably still 
exhibit this waving problem - adjust to spec. or to your tape library - 
take your pick. 

Thats the theory - now the practice. Back-tension refers to the tension 
of the tape over the head drum, this is provided by the felt covered 
metal band (tension band) which is wrapped around the supply reel 
(left-hand reel from the front), the friction providing the tension. 
There are usually two adjustments associated with back tension and these 
can be found near the opposite ends of of this tension band, the tension 
arm operating position and the anchor point of the band.  Adjusting the 
latter position will increase or decrease back tension (you will want 
to increase your back tension which has dropped due to excessive wear 
on the belt).  If you do give it a bash then be aware that poorly 
adjusted back-tension can, at worst, give rise to premature head wear.
Because of the differences between the back tensions of different 
machines, all modern TV's have a dedicated video channel button 
(usually channel 0) which has a shorter flywheel line-timing duration 
allowing the TV timebase to lock up more effectively to unstable video 
sources such as video machines.  Are you using the video channel? - try 
playing the video through different channels on your TV.

Chapter 13) Audio Problems

  13.1) Poor quality sound on non-HiFi VCR

There can be several non-electronic causes for poor quality sound on linear
audio playback:

1. The audio head needs to be cleaned.  A cleaning tape may not be
   effective.  You can use Q-tips and medicinal or pure isopropyl
   alcohol or tape head cleaning solution.  You might as well clean the
   tape guides as well while you are at it - a speck of dirt can cause
   the tape to wander and produce erratic sound.

2. The audio/control head needs to be aligned - particularly the azimith
   adjustment which is the angle the head gap makes with respect to the
   direction of the tape's long axis (I hope this is clear).  You can do this
   if you are so inclined.  Before you adjust azimith, a test for this would
   be to record and then play back a tape on this machine - regardless
   of how far off the azimith adjustment is, the recording should sound good
   (at least as good as one can expect from the linear audio) track.  See
   the chapter: "Tape Path Alignment and Backtension Adjustment".

3. The audio head (and other parts) needs to be demagnetized - use an audio
   tape head demagnetizer.  Stay away from the video heads.  Some
   demagnetizers are powerful enough to damage them.  Make sure the
   demagnetizer you use has a no sharp ends to damage anything - cover with
   electrical tape if in doubt.  Turn on the demagnetizer and move it slowly
   near all metallic parts that the tape contacts - guides, levers, erase and
   audio/control head.  As mentioned, do not go near the video heads.  See
   the section: "Head demagnetizing".

4. The audio head is worn.  If the poor sounds quality really bugs you,
   these can be easily replaced but they are not cheap since generic
   replacements are rarely available.  Alignment will then be needed.

5. Tape path problem causing bad tape-head contact.  See chapter: "Tape Path Alignment and Backtension Adjustment".

6. Your expectations for audio quality on the linear audio tracks on a
   non-HiFi VCR are unrealistic.  The worst will be a stereo VCR in EP
   mode since the stereo tracks are less than half as wide as non-stereo
   tracks.  Best will be SP non-stereo but even this is very poor for music.
   Once you get used to HiFi quality, linear audio sounds like crud.

  13.2) Identifying source of one-channel line (non-HiFi) low audio/hum/buzz

Perform the following 'screwdriver and short tests' to narrow down a
one-channel low audio problem:

* While the VCR is playing a tape, CAREFULLY touch the tip of a screwdriver
  (or other metal tool) to each of the pins on the A/C head - you should be
  able to locate the L and R channels by the buzz resulting from signal
  pickup from the screwdriver.  If the bad channel doesn't respond at about
  the same level as the good one, there is probably an electronics problem,
  not A/C head alignment.

* If you can locate the signal ground for the A/C head, CAREFULLY short the
  output pin of the bad channel head to ground - the hum/buzz/whatever should
  disappear if there is a head or alignment problem.

  13.3) Excessive flutter on VHS linear (non-HiFi) audio playback

While general quality of VHS linear audio is almost always mediocre, there
should not be excessive flutter - wavering in pitch.  Certainly it should
not be noticeable for speech.   How bad music sounds will depend on your
expectations as well.  Here are some possible causes:

* Dirty/gummed up stationary guides or A/C head.

* Lack of lubrication of the capstan or roller guides.

* Excessively tight idler or other clutch.

* Bad capstan motor, especially if direct drive type, or motor driver.

* Bad pinch roller/bearing.  Sometimes aftermarket replacements may be
  inferior and result in the same or worse behavior.  However, usually they
  are fine.

* Video head drum (upper cylinder) which is mounted off-center or which has
  excessive runout or wobble.  This would most likely show up after the video
  heads are replaced.  Sometimes, this may be detected by resting a dry finger
  very gently against the rotating drum - there should be NO detectable

* Servo system problems.

* Power supply problems.

* 'Stiction' between tape and lower cylinder.

* Unrealistic expectations of linear audio quality.  Some VCRs are downright
  terrible, especially at EP speed.  This is normal.

  13.4) No (non-HiFi) sound on new recordings

Sound is fine on pre-recorded tapes or tapes recorded on this VCR prior
to the problem developing.  New recordings have no sound whatsoever.

Make sure your tape isn't bad.  Yes, I know, this is unlikely, but very
old tapes tend to lose oxide along the edges and guess where the audio goes.

If the previous audio is erased but you now have silence, the problem could
be that erase is working but no new audio is being recorded on the tape.
First, check any audio mode or dubbing switches for proper settings.

If you are using the RF input, see if the same problem exists with
the RCA inputs.  Sometimes, dirt/bad connections on the RCA inputs will
trick the VCR into thinking you really want to use those instead of the
RF.  Pushing an RCA plug in and out a few times may clean these off.

(From: Raymond Carlsen (rrcc@u.washington.edu)).

I first saw this problem in Wards (Sharp) VCRs, then later in some
Samsungs. The real problem is a bit of resistance in the connector on
the full erase head. The FE head arm swings back and forth when
loading and unloading the tape, causing the connections to weaken.
That bit of resistance cause the bias/erase oscillator to fail to
start up in record mode. If allowed to run that way, it can burn up
that transistor and other components on the audio board. Just
replacing the bad parts will not fix it for long. Cut off the plug and
direct-solder the full erase head wires directly to the head.

End of problem. Done a bunch of 'em.

  13.5) Audio not present through VCR

Tapes play fine but audio is missing to the TV and when making recordings
using the VCR's tuner.

How is the TV connected?  Through the RF/antenna input?  If through the RCA
jacks, of course, it could be a TV/cable problem.  Bypass the VCR and check.

For the RF, this could be many things:

1. There may be an incorrect source select or dubbing mode setting or a dirty
   set of contacts on a related switch.  Check your instruction manual and
   cycle and/or clean the contacts of any suspect switches.  Unplug the VCR
   for a few minutes to reset the controller - it may be in a weird mode.

2. Dirty contacts on the RCA audio in jack - some automatically assume you
   want to record from there if anything is plugged in.  (Or, you may have
   left your CD plugged into the jack several months ago when you last used
   it!)  Usually, inserting an RCA plug into the jack a couple of times will
   clean the contacts at least well enough to confirm that this is the

3. Bad cable or bad connections inside the VCR.  There is often a separate
   cable for audio (and video) between the tuner and the mainboard - reseat
   and/or test it.

4. Electronic fault resulting in not selecting the audio.  This will require
   a schematic.

  13.6) Previous (non-HiFi) audio is not erased on new recordings

If the old audio track is unchanged - you get the new video but old
audio, check that any dubbing switches are set correctly - to enable audio.

If you are getting a mixture of old and new audio, then there could be
a problem with the audio erase head (part of the A/C head stack) or its

Clean the audio/control head (the stationary head to the right of
the video drum near where the tape re-enters the cassette.  Check for
dirt or tape oxide on or around the audio/control head.

Beyond this, testing will probably require a schematic.  However, if you
can locate the connections to the audio erase head, use an ohmmeter to test
for continuity of the coil.   Check with an oscilloscope for the high
frequency erase signal during record.

  13.7) Poor quality sound on HiFi VCR

The VCR may be switching between HiFi and linear audio at random (with
the HiFi light also flickering on and off or simply not selecting HiFi
audio at all.  This may be happening with only one audio channel (usually
the right channel in this case).

The sound out of a HiFi (not just stereo) VCR should be virtually
indistinguishable from the original and for good quality source
material, nearly as good as a CD.

What to look for if it is really playing HiFi (try at slowest tape speed
as this will have little effect on HiFi quality but will turn the linear
track quality to crud).  Use a tape with a musical recording for this:

* Almost no tape hiss (background should be virtually silent).
* Excellent frequency response (treble notes should sound natural).
* Excellent dynamic range (loud louds and soft softs).
* No detectable wow or flutter (no short or long term wavering in pitch).

However, problems are possible:

* Since the HiFi heads are on the rotating video head cylinder, they are
  subject to the same problems as video heads - and the same difficulties in
  diagnosing head problems.  Dirt, damage, or electronic defects can cause the
  HiFi sound to be absent or distorted.  A broken or badly worn HiFi head will
  simply cause the VCR to switch to the linear audio tracks.  HiFi head
  alignment is more critical than video head alignment so this may need to be

  Try adjusting the manual video tracking control as this will also affect HiFi
  audio tracking and see if this clear up the sound.

* As with video heads, poor quality playback of self recorded tapes but fewer
  or no problems when playing pre-recorded tapes is one sign of worn heads.

  Like video, recording HiFi audio needs to use the heads twice.  Thus, a
  slight loss in sensitivity or frequency response may still enable
  pre-recorded tapes to work reasonably well but will result in problems of
  playing back self-recorded tapes.  Note that slight tape path misalignment
  would not affect self-recorded tapes anyhow but would result in poor
  playback of others - the opposite effect.

* Old, worn, dirty, or bargain basement tapes will have many more dropouts
  than new name brand tapes.  These will show up as noise, streaks, or dots
  in the picture *and* as pops or increased noise in the HiFi audio output.

* It is possible that only one audio channel is affected.  The audio may be
  missing, scratchy, distorted, or fading in and out.  Where problems mainly
  affect one audio channel, it is usually the right one.  One reason for this
  is that it is recorded at a higher carrier frequency (1.7 versus 1.3 Mhz for
  the left channel).  Thus, problems are more likely to show up in the right
  channel due to either worn heads or a misaligned tape path.  Since some of
  the audio processing is separate, electronics problems can easily affect one
  channel as well.

* A whine, buzz, or hum in HiFi audio playback may indicate that the A/C
  head is too high - recording the control track on top of the ends of the
  video and HiFi tracks.  However, other problems - particularly with tape
  interchangeability would almost certainly result.

  Note that A/C height doesn't change on its own - someone has likely been
  mucking with your adjustment screws (and who knows what else)!

  To confirm, record a couple minutes on a brand new or bulk erased tape.  If
  the last 5 to 10 seconds of the recording is clear, the A/C head alignment
  is at fault since it is writing over the ends of the HiFi tracks 5 to 10
  seconds *after* they are laid down and the end of the recorder will be

* A hum or buzz may be the result of problems in concealing the head switching
  point for the HiFi track.  This could require an adjustment or be a failure
  or design flaw.  See the section: "Hum or buzz in HiFi audio".

* Electronic adjustments or faults in the HiFi audio circuitry could of course
  also result in record or playback problems.

  13.8) Help for marginal HiFi heads

Also see the chapters: "Video Heads and Upper Cylinders" and "Tape Path Alignment and Backtension Adjustment".

(From: Jerry ()).

The HiFi heads are more critical than the video heads.  If they are warn down
a bit, they can be very instable.  Sometimes I can get a bit of a better
response by increasing the tension arm tension a little.  If you do this, you
may have to touch up the guides.

(From: Anthony Falvo (afalvo@borg.com)).

I have had good luck making the HiFi tracking point meet the video head
tracking point with slight adjustment of the 30 Hz switch point.

  13.9) Hum or buzz in HiFi audio

(From: Liam Keane (106350.3410@CompuServe.COM)).

The noise you are hearing is FM audio track switching noise - from the
changeover between the hi-fi audio heads on the head cylinder. The difference
between video and audio switching noise is that the video noise can be shoved
out of sight in the vertical blanking interval.  The trouble with the audio is
that our ears listen all the time!  Some VCR's exhibit this worse than others.
You can try adjusting the switching point to minimize it, but by the same
token, some precorded tapes are particularly bad, with Disney tapes being
about the worst I have ever heard.

  13.10) Fluttering or noisy HiFi audio

Where a VCR has seen a lot of use, the video and HiFi audio heads are likely
to be worn.  However, evidence of video problems may or may not proceed HiFi
audio degradation:

(From: (Parker C. (parkerc@halcyon.com)).

Your hifi audio is, technically speaking, not fluttering.  The distortion
you hear is the head switching noise becoming audible as the hifi heads
are wearing out.

On the outside chance you are not dealing with a worn out upper drum, you
should first check the video envelope and confirm that your machine is
mechanically adjusted correctly - i.e. check that the drum guides have not
slipped.  Hifi audio would typically become distorted if the tape path is
not adjusted correctly.  Audio playback level will not help the situation.
Hifi Record levels almost never need to be adjusted, unless someone has
been tweaking them in the field. (hint, hint).

A note on record levels:  occasionally we find that decreasing the video
record levels on machines with poor hifi audio recordings will quiet
things down for a little while.  Did everyone get that?  (decreases the
video penetration into the hifi region of the tape).

  13.11) Squealing noise from VCR in certain modes

Unusual noises from inside the VCR may be an indication of a problem or just
a badly made cassette - try a different one.

The most common cause for a squealing noise are tired weak belts that are
slipping.  Less likely is the need for lubrication.

* A squeal when entering play or record mode - with the VCR perhaps aborting
  the operation -  is usually caused by a slipping loading belt.

* A squeal during fast FF or REW may indicate a slipping drive belt.

* A squeal or whine during play or record (perhaps intermittently when the
  video head drum is spinning) could be a worn video head drum bearing
  or dirty or improperly positioned static brush (see also: "High pitched whine from inside VCR").

See the appropriate sections on cleaning, rubber parts, and lubrication.

* A whine or buzz from the audio during playback of tapes not recorded on this
  VCR may indicate a grossly misadjusted A/C head - the linear audio heads are
  picking up the ends of the video tracks due to the A/C head being too low.

  Note that A/C height doesn't change on its own - someone has likely been
  mucking with your adjustment screws (and who knows what else)!

* A whine from the audio (of the TV) while using the VCR may indicate
  bad grounding of the internal shields, other bad connections, or
  electronic problems.

  13.12) High pitched whine from inside VCR

Your first thought is probably of an expensive repair to a motor bearing
or replacement lower cylinder.  If there is a high pitched whine coming
from inside the VCR when in PLAY, REC, or other mode which spins the video
heads, you may simply have a dirty or improperly positioned antistatic brush.

There is usually a metal strip with a carbon contact pressing against the
center of the video drum spindle either above or below the deck.  In rare
instances, the bursh may be BETWEEN the upper and lower cylinders requiring
more disassembly.  It is very common for it to vibrate is just the right way
to sound like a cat being strangled.  Gently press on this strip or lift it
off of the spindle while you hear the sound.  If the whine disappears,
cleaning and slight repositioning of the strip should be all you need to do.
Do not remove this strip - it is needed to ground the rotating drum to prevent
static buildup and video noise problems (see the section: "Firing (static) lines in picture during playback".

  13.13) Tapes play back in a foreign language

"Have recorded tapes with a Mitsubishi U52 that play back in English on
 same, but play back in Spanish with some other VCR's.  What's up?"

(Portions from: David R Mulligan (skipper@interlog.com)).

It sounds like you are recording the SAP audio channel on the mono audio track,
but normal on the HI-FI track.  This would indicate that your television
station broadcasts a Spanish dub over the SAP channel for those who prefer
that language.

Check the position of the audio playback source select.  Also, any problem with
the HiFi record or playback would also result in the VCR defaulting back to
linear track playback.

Chapter 14) Signal and Interference Problems

  14.1) VCR color problems

There are two typical situations:

* Playback is always in B/W.
* Record is B/W but playback has normal color.

If you can play pre-recorded tapes in color but tapes recorded on this VCR
do not play back in color, there may be several possible causes.  The
simplest is that your input signal is too weak - a misadjusted antenna or
cable with a large number of splitters - and the VCR's color killer thinks
there is no color.  Sometimes the threshold for detecting the color signal is
set higher on the VCR than the TV which you are using to monitor the

Some questions:

* Is the color TV's fine tuning set correctly?
* Does it play pre-recorded tapes in color?
* Does the tuner output produce color?
* Does the video output work in color?
* Is the problem the same for all recording speeds?
* Do the tapes you record on this VCR play in color on another one?

If the answer to all but the last question is 'yes', then the problem is most
likely in the video/chroma circuitry associated with recording function.  It
could be as simple as the color killer setting being too low.

Possible sources of problems with color recording:

1. Weak signal - check and/or adjust antenna.
2. Color Killer set to low.
3. Problems in tuner - does the video output work in color from the tuner?
4. Problems in chroma circuits.
5. Sometimes, marginal heads - less likely if it plays in color.

If recording works fine as indicated by tapes made on this VCR playing
fine on another one but pre-recorded tapes do not play back in color and
the VCR works fine in all other respects there could be several possible

1. Weak chroma signal level from VCR.
2. Color Killer set to low on TV.
3. Problems in chroma circuits.
4. Marginal or dirty video heads.

Note that in all cases of missing color, checking with another TV and/or
adjusting the TV's controls should be tried first as slight differences
in signal levels between tuner and playback may cause a TV with marginal
settings (fine tuning, color killer, chroma circuits) to switch unexpectedly
between color and B/W.

  14.2) RF signal problems

First determine whether there is a problem with broadcast or cable, playing
tapes, or both.  If it is only broadcast or cable, then your source may be at
fault.  If it is fine with the VCR off but noisy when using its tuner, the
problem could be in the tuner itself.

Verify that the direct video output (RCA jacks) works properly with a
pre-recorded tape.  If this is noisy as well, then there are problems
with the video circuitry or video heads.

If there are problems with the Channel 3/4 output but the direct video
outputs are fine, then suspect a weak or dead RF modulator.  This is
a little metal metal box with the Antenna In and TV Out connectors.
It has circuitry which switches between the VCR's internal video
signal and the antenna input.  It also converts the video baseband
signal to the channel 3/4 output required by the TV.

Before you conclude that the RF modulator is to blame, check that the channel
and fine tuning of the TV are properly set and that there are no other
problems with the TV.  Test the VCR with another TV.  It could be that
the signal from the VCR is just a little weaker than it is used to be.
Try moving the channel 3/4 switch back an forth - it may have developed a
bad contact.  Try the other channel (3 or 4) - it may work better.  Try
moving the VCR away from the TV - sometimes interference from the TV will
degrade the video quality.

If you do conclude that the RF modulator is at fault, generic
replacements are available from the parts sources listed near
the end of this document or other electronics distributors for less than
$25.  Replacement is straightforward since there are only a couple of
soldered connections but getting to the unit physically is sometimes a

  14.3) VCR will not tune broadcast or cable

Are you sure that the input signal is making to the VCR?  Does the pass-
through connection work?  Double check the connections.  Connect the cable
you have on the ANTENNA IN of the VCR directly to the TV.  Make sure it's
center pin is not bent over or broken off.  Try a new cable.  Is the tuning
mode switch (broadcast, CATV, etc.) set correctly on the VCR?

If the signal is preset into the VCR, there still may be a bad connection
inside preventing it from making it to the VCR's tuner.  Sometimes, there
are RCA style plugs inside that work loose.

Otherwise, the tuner of the VCR is not working.  This could be because it
is broken or power to it is bad or missing.  If all other functions
of the VCR are working, it is likely (though not guaranteed) that the
power supply is fine.  There could be bad connections or dirty connectors
as well.

Beyond probing for bad connections and verifying your antenna hookup, there
is not much that can be done without a service manual and test equipment.

  14.4) Interference patterns such as parallel or diagonal lines

This may be due to the proximity of the VCR to a TV or other component,
outside interference, or a fault in the VCR.

Determine if it in the video signal or is it only present when the VCR is
close to or sitting on/under the TV?  If so:

* Have you rearranged your setup recently?  It is common for TVs and VCRs to
  interfere with each other's operation.  Your only easy fix may be to shuffle
  the components in your entertainment center.

  One simple test to see if it is the TV doing the interfering is to record
  a program partially with the TV off and then with it on - without changing
  anything else.  If the quality of the recording is noticeably worse with
  the TV on, you know what is at least partly to blame.

  It is probably interference from the TV's switching power supply, deflection,
  or other circuits getting into the low level video circuits of the VCR.
  Either the TV or VCR or both are inadequately shielded.  Hey, but the makers
  saved a few cents!

  Is probably isn't the cables but see if moving them around changes anything.
  If it does, then better (shielded) cables might help.

  It might be worth trying a position a grounded copper sheet between the TV
  and the VCR.  I don't know how much if at all it will help.

Does it happen when watching from the antenna/cable or only when a tape is
playing or recording?

* Interference patterns on cable may indicate a problem with the cable company
  or the hookup.  It may even be system wide and under investigation - such
  temporary service problems are not uncommon.

* If you are using one or more splitters to distribute the signal to multiple
  locations, be aware that each one introduces some signal loss and eventually
  this results in noticeable degradation making the system more susceptible to
  even low level interference which might otherwise be undetected.

* Interference patterns while using the antenna may indicate just generally
  poor reception.  Try repositioning the rabbit ears or outside antenna (if
  you have that option.  Also check the connections and wiring - all the
  twisting and maneuvering can break or damage antenna cabling.

  If you live in an apartment complex - especially newer building of steel
  or steel reinforced concrete construction - reception may be inherently
  dreadful.  Many of these offer a rooftop antenna feed or cable and for good
  reason.  Try relocating the equipment - sometimes a different part of the
  room will have fewer problems.

* Interference patterns only on recorded tapes that was not there in the
  original program may indicate a problem in the record circuitry of the VCR
  or interference from the TV (only if on).

* Interference patterns only on playback of tapes regardless of where they
  were recorded may indicate a problem in the playback circuitry of the VCR
  or interference from the TV.

Did this just start suddenly without you changing *anything*??  Does it now
happen at all times of day?

* If it does not happen all the time, try to determine what is common about
  when it does occur.  Consider other sources of interference - local ham
  radio operators or other transmitters, light dimmers, compact or other
  fluorescent lamps, vacuum cleaner - even your microwave oven.  Although
  less likely, it may be a neighbor's appliance doing the interfering.

* To eliminate the VCR as the source of the problem, you may need to take it
  on a field trip to a friend or relative in a different neighborhood.  If
  the patterns are still the same, it is probably a fault in the VCR and
  not outside interference.

  14.5) Firing (static) lines in picture during playback

These may be described as static or short bright or dark lines in the picture.
They usually have a sharp start and may trail off or stop abruptly.  They may
be occasional (once every few seconds) or frequent (multiple instances per
video frame).  Also see the section: "Are your video heads really bad?" video
head problems as large quantities of firing lines may be due to dirty, worn,
or defective video heads.

First, try a different tape - preferably a new recording made on a different
VCR or a new commercial video.  It is possible that these streaks are simply
due to dropouts on the tape - missing bits of oxide or dirt causing momentary
loss of video signal.  Old, worn, or cheap off-brand tapes are particularly
prone to dropouts.

One characteristic of dropouts is that they may span video lines as well as
video frames.  If your lines are very short and random, they may be caused by
a dirty, missing, or improperly positioned video drum static brush.  In most
VCRs, you will see a metal strip with a carbon contact pressing against the
center of the video drum spindle either above or below the deck (or in rare
instances, BETWEEN the upper and lower cylinders).  The brush is there to
provide electrical contact between the rotating video drum and the stationary
lower cylinder and chassis.  This is necessary since the bearings on which the
upper cylinder rotate may not provide adequate contact and any static buildup
caused by the spinning head cylinder rubbing against the tape may discharge
through the bearings resulting in these firing lines.  Carefully remove the
static brush and clean the end of the spindle and carbon contact.  This may be
all you need to do to remove the static lines from your picture.

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Written by Samuel M. Goldwasser. | [mailto]. The most recent version is available on the WWW server http://www.repairfaq.org/ [Copyright] [Disclaimer]