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The most common cause of a VCR eating tapes is a dirty/worn idler tire preventing the takeup reel from turning. See section: "General guide to VCR cleaning and rubber parts replacement". The idler tire transfers motor power to the appropriate reel hub. If dirty, worn, dried out, glazed, cracked, or otherwise deteriorated, it will slip and cause the takeup reel (in play mode) to stop turning at some point. Hopefully, the microcomputer senses this and tries to wind the tape back into the cassette. But, you guessed it, this requires the idler tire so you end up with a mess of tape inside the machine. When you go to eject, you may get the cassette with a tape loop hanging out. If you are careful, you may be able to extract the tape without crinkling it too badly but don't just pull - it will break or be hopeless damaged. You will need to remove the top cover and carefully lift the tape loop out of the machine and wind it back into the cassette. If there is any significant crinkling or a partial break in the tape, discard the cassette. If it is priceless and irreplaceable, see the section: "Recovering damaged or broken tapes". DO NOT try to use it or just return it to the video store without informing them of what happened - it is unfair the next renter as a badly crinkled or partially broken tape can destroy expensive video heads.
(This may also apply to other modes for a VCR with a 'quick start' or 'instant start' transport.) If your VCR aborts playing unexpectedly and shuts down and then, pushing EJECT results in a tape loop hanging out of the cassette when it is removed, this is considered tape eating - refer to the section: "VCR eats tapes". However, if all other functions work normally but ejecting results in a tape loop, this section is for you. Using a garbage cassette, try to observe exactly what is happening during EJECT. Specifically, is the operation terminating early or is there some problem with the appropriate reel not turning or not turning reliably or quickly enough? Is the tape getting hung up on the roller guides or on some other guideposts? As with tape eating, the most common cause is dirty, old, deteriorated rubber parts - particularly the idler tire - preventing the tape from being fully wound back into the cassette. Therefore, the first step is to follow the procedures in the section "General guide to VCR cleaning and rubber parts replacement". If this only started happening after you had the VCR apart for any reason, recheck your work - you may have neglected a connector, have the mode switch slightly out of position, or have gears which are improperly timed. Many VCRs determine that the tape is completely wound back into the cassette by sensing rotation of the non-driven reel indicating that the tape is pulling on it as a result of being tight and pulled by the driven reel. If this sensor is defective, disconnected, the signal is noisy, or the associated electronics are faulty, the operation may be terminating early. As an experiment to confirm this, use a cassette cheater and while the VCR thinks it is winding the tape back into the cassette, turn the non-driven spindle by hand - this should stop the operation instantly. If it stops too quickly - before you turn the spindle, there could be a problem with this sensor. It is also possible for a failure of one of the reel brakes to allow one of the reels to continue spinning even after motor power has been shut off. Alternatively, a sticky brake band may increase the driven reel torque and fool the microcontroller into thinking that the tape slack has been taken up. If the roller guides get hung up on the tracks while being retracted, even for an instant, the tape may become tight around the roller guides, pull on the non-driven reel, and stop the operation before the tape is fully wound back into the cassette. Check for obstructions and for adequate lubrication of the roller guide tracks. If it is a late model Sony, the 'half loading arm' could need lubrication. See the section: "Late model Sony VCR munches tape on eject".
(From: Gary Woods (gwoods@albany.net)). Usually under humid conditions, but not condensation of tape path, tape has excessive amount of drag around the scanner. S-tension is OK, or even a little light, but there is so much drag around scanner that the capstan skids. * Reducing S-tension helps. * Cleaning scanner helps. * Cleaning capstan and treating pinch roller with PRB "conditioner" (smells like ether) helps. None of these is a *real fix* and the problem recurs eventually. Somewhat dependent on the tape, but real problem appears to be drag around lower drum. Anyone know of a fix other than a new scanner? (From: Daniel Schoo) This seems to happen mostly on machines with a lot of play time. There is supposed to be an air film between the tape and drum to facilitate the reduction of friction. When the drum gets worn and polished the air is squeezed out and the tape sticks. Little can be done for this. You could replace the drum but this is expensive and not worth the effort for most machines. The other option is to try and rough up the drum surface by light sanding with 3M Scotchbrite(tm). I don't need to go into detail about how difficult this is to do correctly but what the heck you don't have anything to loose. Just be careful and stay clear of the heads. BTW I have seen "cleaning" tapes that rough up the drums very well! Picture jittering vertically may be similar problem. Tape is not moving smoothly over the head drum.
Check whether the backtension on the tape is applying so much pressure to the drum that it is slowing it down. Backtension should be just enough to keep the tape in good contact with the drum. If it is too tight, then you backtension felt may be worn or adjusted too high. There is a lever just as the tape exits the cassette - push this to the right to reduce tension. Someone may have attempted to repair a broken backtension band and reduced its length - I got a VCR for repair once where this was done. If it is not the backtension, check free rotation of the drum when it stops - I bet it turns as freely as always. Could be a part in the motor driver that is faulty and failing when hot. However, the bearing could be worn or dry which would require disassembly and lubrication or replacement of the lower cylinder (assuming this is where the drum bearings are located).
Typical symptoms: front panel display is active, it may be possible to
set the clock or timer and change channels, but all transport related
buttons are totally inert. Perhaps there is no response to any button.
The VCR may or may not refuse to accept or eject a cassette.
This could mean many things including motor problems as well as a general
power supply or control system failure. However, here are a several things to
try first:
0. Check for cockpit errors - Someone may have accidentally set it for 'timer
record' or in 'parental lock mode'. Is there a little clock or key symbol,
'L', (or something else you don't understand) displayed? Inspect the
position of any slide or push-push switches.
* Timer mode may be set by a pushbutton, push-push, or slide switch, or from
the remote control.
* Parental lock is usually accessible only from the remote control. See the
section: "VCR shows LOCKED in the display".
Consult your user manual if in doubt about how the thing is supposed to
work!
1. Cycle power - unplug the VCR from the wall (don't just use its power
switch) for a minute or two to see if the microcontroller simply got
into a confused state. This is more common than you would think. A
random power surge can do it. The VCR may have gotten into a bad
(mechanical or electrical) state.
2. Unplug the VCR and remove the covers. Rotate the shafts of each of the
motors (cassette loading and tape loading or main motors depending on
your VCR) clockwise a couple of turns (assuming there is no resistance
to turning). Plug it in and listen for initialization sounds - it should
detect that the mechanism has been moved and then reset to a safe position.
See if it is now behaving.
3. If (2) doesn't do anything, try several turns counterclockwise instead.
4. If still no improvement, there may be more serious power supply, motor,
or control system problems.
If any of these appears to solve the problem, it is quite possible that you
will never experience it again. However, a dirty mode switch (see the
section: "VCR mode (sensor) switches" may have resulted in an overshoot
to a bad mechanical state and without cleaning or replacement, the same
thing may happen again.
The clock runs either off the power line (zero crossings of the 50 or 60 Hz waveform) or from a crystal (possibly a reference derived from one of the other frequencies used elsewhere in the VCR). Conceivably, a bad backup battery or supercap might result in the clock remaining in setup or power fail mode. Unfortunately, this probably isn't much help since identifying and locating the relevant components will be next to impossible without a schematic :-(.
You turn power on or just plug in the VCR to the AC outlet and it goes through the whirring sounds of playing a cassette - but there is not cassette present. However, first try unplugging it for 30 seconds or so and plugging it in again. The microcontroller may just have had a bad day and gotten confused - either a bad reset or a power glitch. Assuming this doesn't help: This could be due to a faulty end sensor or a bad LED or light bulb that provide illumination for the end sensors. If either sensor's output is the same as when a cassette is present (blocked), it very likely that the microcontroller will be confused. In some designs, this is indistinguishable from a cassette actually being loaded. If the 'cassette in' indicator is on, then this is likely. BTW, if a VCR uses an actual light bulb for that central light source and it is not lit when you attempt to load a cassette, it is burnt out. The LEDs used in most modern VCRs are IR and invisible, however. With somewhat similar symptoms, it is also possible that the VCR is not able to complete the startup initialization due to a slipping belt, gummed up lubrication, or other mechanical or motor problem. The clincher would be if you manually load a cassette (by turning the appropriate pulleys, etc. with it unplugged) and it then plays the cassette properly and acts normally until you try to eject. However, don't try this unless you are sure of how the mechanism works as it is easy to cause damage.
You press PLAY and the VCR gets halfway through loading the tape and suddenly aborts and shuts down. Or, you put a cassette in and it is immediately spit out as though it tasted bad to the VCR. Or, you press PLAY and the VCR goes into REWIND mode. Or, you pressed REVIEW and it ejected or attempted to eject the cassette. Before you break out the screwdriver or shotgun, cover up the IR remote sensor and cassette slot. Some types of electronic ballasted fluorescent lights may confuse the remote control receiver. Or, someone or something may be sitting on the remote hand unit or it may be defective and continuously issuing a REW command! Excessive general illumination may even make its way into the tape start and/or end sensors and trick the VCR into thinking the tape is at one end. (If you are working on the VCR with its cover removed, block any stray light from hitting the area of the tape transport to see if behavior returns to normal.) Assuming neither of these is the source of the problem: First, eliminate the possible mechanical causes such as slipping belts or a bad idler tire which could prevent the VCR from completing your requested action - it then shuts down or attempts to return to a 'safe' position. Bad connections are a possibility but not as likely as in a TV or monitor, for example. However, some VCRs (certain JVCs and clones, for example) ground parts of the circuitry via the circuit board mounting screws and simply tightening these are all that is needed to affect a cure. The microcomputer or its associated circuitry could be defective as well - but this is not as common most people fear. Occasionally, a faulty power supply may result in similar behavior. Its output voltages may be marginal, drop under load, or have excessive ripple due to dried up filter capacitors. However, a more likely possibility than any of the above is that a sensor assembly present on most VCRs called the 'Mode Switch' or 'Mode Sensor' is dirty or bad. See the section: "VCR mode (sensor) switches". Failure of the Mode Switch is a very common problem with numerous VCRs of many makes and models.
In order for the microcontroller in a VCR to confirm correct functioning and
completion of various operations like cassette and tape loading and roller
guide position, some mechanical sensor feedback is normally used. The most
important sensor assembly in most VCRs is called the 'Mode Switch' or 'Mode
Sensor'. The purpose of the Mode Switch is to inform the microcontroller
of the gross position of the mechanism at all times. For example, the mode
switch may have 5 positions:
1. Tape unloaded and cassette out.
2. Tape unloaded and cassette in.
3. Tape half loaded against A/C head but not around drum.
4. Tape fully loaded around drum and roller guides at V-Stoppers.
5. Pinch roller pressed against capstan - play/record position.
The microcomputer monitors the outputs of the Mode Switch continuously when
it is executing a mechanical operation (some monitor it at all times even
with power 'off'). If an operation takes too long to move from state to state
or an incorrect state transition occurs, the operation will be aborted and
an attempt - possibly several - will be made to return the transport to a
'safe' position - unloading the tape and possibly ejecting the cassette.
If the Mode Switch contacts are dirty or worn, or if it has somehow loosened
on its mountings and shifted slightly, one or more of these positions will
report back incorrectly or erratically signaling an error condition. For
example, a transition from state 1 to state 4 directly would totally confuse
the poor controller. A Mode Switch that shifted out of place (or where
other timing relationships in the VCR are messed up) might result in certain
operations stopping at the wrong position as well. For example, if the
Mode Switch shifts one way, the pinch roller may never quite press against
the capstan or the roller guides may not snuggle up to the V-Stoppers as
they should in play mode. If it shifts the other way, operations may fail to
complete and run against the mechanical stops - stripped or broken gears may
even the result.
A dirty or worn mode switch can result in cassette or tape loading, or
unloading or eject operations aborting and resetting or the VCR shutting
down. For example, some Emerson VCRs will move part way when loading and
then shut down. Repeated attempts may get them fully loaded and then PLAY
or other tape movement operations will work properly. However, unloading
will result in similar cranky behavior.
Mode Switches are usually linear or rotary slide switches with 4 or more
output terminals. They may or may not be easily accessible. On some, they
are visible once the bottom cover is removed. On others, they are buried
beneath a bunch of mechanical doohickies (technical term). Some are
removable with a screw or two and a connector. Others require desoldering
and the removal of a whole lot of stuff - all of which must be carefully
replaced with exactly the same timing relationships - just to gain access.
Once, you get at them, you can often snap apart the housing and use contact
cleaner on the sliding contacts and surfaces. I usually do not use any
kind of lubricant as it can gum up on the contact surfaces resulting in
erratic outputs - possibly the cause of the original problems in the first
place. Some may not come apart and replacement is the only option if
squirting contact cleaner through any visible openings does not help.
Note that without disassembly, there is no way of knowing if there is
still dirt or gummed up grease inside or if the contacts are actually
pitted. Conversely, if squirting in some contact cleaner does not help,
the mode switch may still be the problem since you have no way of knowing
how far the contact cleaner penetrated or whether it had any effect.
Sometimes, bad solder connections to the mode switch are the only problem.
However, be very careful about not moving anything and take careful notes
on the position of any parts that you disconnect as critical timing
relationships are controlled by the gear positions. Stripped gears or
other broken parts may result when the mechanism cycles. Also, in certain
positions, levers or sliders operated by the mechanism you remove may
spring out of position and you will need to make sure they get put back
into the correct slots in any cams when you are done. Mark all gear
positions even if they do not seem to be critical. See the section below
on how not to mess up your day by ignoring timing marks or more simply:
"Mechanical relationships in VCRs".
Note that if you experience erratic behavior with a VCR manufactured
by Sharp, the probability of a dirty mode switch is very close to 1.
See the section: "Erratic behavior of Sharp VCRs".
The complexity of the mechanism in a VCR can be quite intimidating. To avoid total frustration and really messing up your day, before you remove anything mechanical, take careful notes of precise relationships of any gear, lever, switch, anything that might possibly get back together in an ambiguous way. Often there are 'timing' marks on the gears just as you would find in a lawnmower or automobile engine. These will be little arrows or holes which will line up with stationary marks or with each other on adjacent gears when the mechanism is in a particular position. Often, it is best to put the mechanism in the position where the timing marks line up because there may be fewer levers, cams, etc. which are under pressure or tension in this position and thus fewer things to pop out at you. If there are no apparent timing marks, make your own with a scribe or pen. Sometimes mechanisms that at first appear not to be critical are obscured in such a way that they really control critical timing. So, when in doubt, make more notes than necessary - with diagrams.
This may mean that pressing on a circuit board, flexing a cable, or operating
the VCR in different orientation affects behavior. Sometimes this is affected
by temperature as well.
Note: if this only happens while servicing, confirm that excessive light is
not affecting the start/end sensors.
Do not confuse these sorts of symptoms with those indicating a faulty or dirty
mode (sensor) switch. See the section: "Erratic behavior in various modes".
* Unlike TVs and monitors which have high power circuitry and are prone to
cold solder joints from poor manufacturing or thermal cycling, most of the
circuitry in a VCR is low voltage and low power. Although problems with bad
connections to these components is relatively rare, visual inspection
should still be performed where erratic behavior is noted.
Exceptions include:
- Power supply regulator(s) or switchmode power transistor (depending on
type).
- Motor driver (power) transistors or ICs - particularly those for the
main (capstan/reel) drive and video head drum.
- RF, video, and audio jacks since they may be stressed mechanically.
* Internal multiconductor (crimp terminated) cable connectors. These may just
deteriorate with age and use. Clean and reseat the connector(s).
* Circuit board ground screws. One or more of the screws holding a circuit
board may also be providing a ground connections. These can work loose or
corrode. Remove screw, scrape corrosion, and/or tighten.
* Hairline cracks in circuit boards. If the VCR has been dropped, this is
very common. Sometimes, these are very difficult to locate visually but
locate them you must! See the section: "VCR was dropped".
* Broken or shorted wires. Some of the individual wires in various signal
cables are quite thin and fragile. Overzealous movement of circuit boards
while replacing belts or other maintenance operations can easily pinch
these resulting in immediate or delayed failure. This may also take place
when replacing boards. It seems that the manufacturers seem to make it
impossible to squeeze all the wires back in where they came from!
CAUTION: Always try to avoid pulling on the wires when removing a connector.
This will minimize stresses which could result in the wire conductor breaking
off inside the insulation - this would be very difficult to locate.
You were watching your favorite tape and suddenly the VCR emits a mechanical eek and is now dead - or you press eject and the VCR shuts down without regurgitating your tape. Worse yet, someone (we will not point fingers) forcibly removed the tape to return it to the video store. Assuming that 'forcibly' does not mean that permanent damage was done, then the first place, as always, to check is the idler tire and then all other rubber belts. At this point it is hard to say whether your problem was compounded by the removal of the tape. If any gears were shifted with respect to one another, parts bent, or springs sprung, then without a service manual, it would be difficult for a technician let alone someone not familiar with your VCR to repair it. An error at power on usually means that the microcomputer thinks that it is unable to put the mechanism into a 'safe' position. This could be due to slipping belts, broken gears, a bad motor, shifted sensors, or faulty electronics. The original symptoms may have been a slipping idler preventing the takeup reel from rotating allowing tape to spill into the machine. Power on problems may be more serious. See the section: "VCR is failing the power-up sequence".
Here is a true story of forced eviction of a tape and the consequences. :-( This teaches you two lessons: Don't use violence to remove a stuck cassette and mark all gear, lever, sliders, etc. timing relationships before you disturb anything! (From: AL (kb8wcq@tir.com)). "I have a Panasonic VCR (model PV-4820) that will not acknowledge tapes. The original problem I found was in the power supply. I replaced all the electrolytic caps, and the PS now works- all the outputs measure OK and the display and tuner controls seem to work OK. But once the PS went bad, it would not take in tapes, so the owner decided to force one in. He sheared half the teeth off of the 'link gear', which I replaced, but it still will not accept a tape. I can manually push a tape all the way in, with some resistance, until it sits down on the reels, but it is not acknowledged in any way. If I don't hold it down, it springs back out." It sounds like you possibly failed to retime the link gear in relation to the rack gear on the loader assembly. If that's the one I think it is and you have not timed one (of course this is something the average person does, say once a week? :-) --- sam) before, you probably should get the manual. Or try this: Remove the carriage assembly, turn the VCR on its side, press and hold the little height change lever (bottom side, near the solenoid), manually turn (CCW) the large belt-driven pulley until the mechanism is in the full eject position, note the position of the link gear, turn the large belt-driven pulley in the opposite direction until the link gear makes exactly one revolution, re-install the carriage (in the eject position) making sure the carriage gear and the link gear mesh properly. Other than that it's pretty simple... Assuming of course nothing was disturbed with the gears below the deck, and that the link gear, mode switch, pressure roller lift cam, etc', are in their proper position. Sounds simple enough! --- sam :-)
This often means that the internal microcomputer found the mechanism in
an unusual state and was unable to reset it. Some VCRs will actually
move portions of the mechanism to make sure that everything is ok
to accept a tape. Failure here may be the result of a slipping or broken
belt or a belt that has popped off of its pulleys, gummed up lubrication,
or some other mechanical fault. How old is it? Rubber parts tend to
become smooth and lose their elastic properties ('rubberiness') after
a few years. Does the VCR make any kind of whirring sounds before
shutting down? This would mean that it is attempting to move something
back into position. Is there a tape in the machine? How about a toy, peanut
butter and jelly sandwich, or a little applesauce? It could be a sensor
or other electronic problem, but check out the mechanical possibilities first.
On a VCR which has been cleaned and with good rubber parts:
VCRs have a light or LED (IR, infrared) in the middle of the mechanical
assembly that detects the end of tape. When a tape is loaded the
tape will cover the sensor. The controller can tell if the tape is at the
beginning, middle, or end by the sensor. The is achieved by a clear
leader at the beginning and end of the tape. The microcontroller will detect a
problem if the sensors do not detect the light or LED (middle of tape)
and the carriage assembly is up (no tape loaded). The VCR will shut down.
1. If you have an incandescent light and it is not lit, it is burned out.
If you have the LED type you can buy an IR tester from an electronic
parts supplier or construct one as described at the end of this document.
Replacement LEDs are readily available.
2. The VCR might be in a confused state. Many VCRs have a belt that
drives a loading motor. This is the motor that drives the tape around
the heads. If those guides are not fully retracted, the VCR shuts down.
Check the belt and replace if necessary.
3. Ensure the tape guide assembly is fully retracted by physically turning
the appropriate gears.
4. Some obstruction is preventing part of the mechanism from resetting.
Visually inspect for foreign objects or rough edges on something preventing
full movement. Dried up grease can also cause this.
5. A gear has slipped a tooth and one part of the mechanism does not track
another. This may happen if a tape was forcefully ejected after being
eaten. You may find that a tooth has actually broken off.
6. If this occurred after having disassembled part of the mechanism, confirm
the timing relationships. Make sure belts are installed in the correct
locations - and on the correct sides of any intermediate pulleys where
belts link more than two pulleys.
Without a service manual, determining the correct relationships for all
gears may be impossible, but if only one has slipped you may be able to
locate timing marks near the edges of the gears which should line up -
usually when the tape is unloaded. (portions from michael@marconi.nsc.com)
Your VCR has worked fine for several years but now you get the 'DEW' warning in the display and no tape functions work. The dew sensor is intended to prevent operation of the tape transport if the humidity is so high that moisture would build up and cause the video tape to stick to the rotating drum and damage the heads or get hopeless tangled as a result. First, perhaps the dew warning is telling the truth. If you have just moved the VCR from a cold area to a warm one, let it sit for an hour or so and see if the dew warning goes away. If you just fished it out of the toilet or scraped stewed peaches from the interior, well, dew may be the least of your problems. Assuming that there is no reason for a dew warning, the dew sensor may be bad or have changed value. There may or may not be an adjustment for this. Before you go inside, try unplugging the VCR to clear any spontaneous fault condition - see the section: "VCR has gone whacko". The dew sensor is a resistor that changes value when there is condensation. If the sensor is bad, you should be able to replace it with a resistor and keep the VCR happy. You should be able to determine the appropriate resistance by trial and error. If it is the type where the resistance decreases with moisture and the controller does not care if the resistance is too high, then you can just remove it. Either way, you have now lost the protection that the dew sensor provides. Replacement is obviously best. Don't overlook the possibility of a bad connection - it may be plugged in and just need to be reseated. One type looks like a ceramic board, maybe 1/4" - 1/2" on a side with a silver/gray printed circuit pattern. If the A/D or whatever is used to determine when there is dew is faulty, then you will most likely need a service manual to troubleshoot it.
You go and try to play a tape and the VCR displays the word 'LOCKED' or perhaps just a flashing 'L' in the display. This may mean that the VCR has somehow been programmed to prevent use by unauthorized kids (you are not reading this if you are a kid, right?) Even if your model does not have this feature, the same basic chassis is probably used for a range of models so it could have gotten into a confused state. * Sometimes, just pressing the PLAY, POWER, VCR1, VCR2, (or other much more obscure) button on the remote control (it may be designed not to work from the front panel) for 10 to 20 seconds will clear this mode. Some remotes have a little 'key' symbol. How logical! Press it. * Unplugging the VCR for a minute or two may work. Unplugging for long enough to drain the backup battery will probably work but you may then need to reinitialize the clock, channel selection, and programming. * Best bet is to check your instruction manual (you can locate your user manual, right???).
Suppose your just-out-warranty VCR is now acting up for no apparent reason - making strange sounds, forgetting its programming, refusing to cooperate, etc. I don't know what kind of recourse you may have as an unsatisfied consumer, but I would try to get some resolution through your place of purchase. Such a VCR has all the symptoms of Alzheimer's disease - it should not be failing in these ways so early in life unless it is under penalty of hard labor in the damp snake infested dungeon of an English castle! Or it has been the depository for peanut-butter-and-jelly sandwiches, applesauce, or marbles! All the usual recommendations of cleaning and checking rubber parts and so forth apply to units that have seen significant use or are a few years old or both. Something this new under normal use should not be causing this amount of grief. However, sometime I wonder whether using a machine very little contributes to problems. First try your place of purchase - there may still be some degree of interest in maintaining customer satisfaction. If you have given up on the store, start by checking the rubber parts for dust and deterioration (with that kind of use, dirt should not be a problem, but dust or smoke can accumulate), check for adequate lubrication (but don't add any unless it is definitely needed and then only the smallest amount - VCRs do not need much oil or grease and too much will just compound your problems - and check for foreign objects especially if there are small kids about.Go to [Next] segment
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