vcr head crashes or tracking error

80 percent of vcr poor picture flickering is not dirty heads some times the clutches on supply reel or take up reel starts slipping or the belt is worn also their is back lash breakes that stick tracking is effected flickering on top of pix speed in sound wrong sometimes threading belt does not thread in tape all the way and tape is loose on post. also i have seen it where the tape transport does not set cassett down in machine all the way will cause edge damage on tape and tracking is effected.most of this can be prevented with maintance every three or four month just even a visiual inspection to make sure their no objects inside will stop this a little 3-1 oil here and there would not hurt use in places spareingly. and know i have found jelly and peanut butter sandwich in tape transports form children play small toys you name it i seen it cookies toast, paper pictures, pens, pencils coloring cranyons art supplies children would use. the signs of head damage is the following.1-flickering snow on ep and not sp sp ok this is adamaged heads.for ep tips are missing this is caused by tape cleaners.or bad roll of tape with wrinkles damage tape should be thrown away.2-a sign of a bad heads is black lines appearing through the picture now and then this is a sign of a head with a lot of hours of playing or recording the gold tip is badly worn.another sign is recording has a muddy look video look dull this is ware.picture has snow over entire picture flickering is dirty heads and should be cleaned manually no tape cleaners and no quick fixes or short cuts their is not any way. by hand is the only way to save the heads.q-tip with shammy.in comming editiorals i will explain how tape tracks are layed down by a vcr. my trainning is by sony type 5 vtrs 2600 vtr 2800 vtr, beta max, beta vcr-c ,vhs-beta-c,and vcr retail.



in a four headed machine only two heads are used at a time one pair ep is tune for that speed only for max preformance.same goes for sp.the only time all four heads are used is in still frame or pause head speed is advance to accomplish this.each head scands 262.5 lines at a time odd lines first.even lines second remember the vertical circuit trouble shooting editioral. know remember in the U.S.A. we scann analog crts with 525 lines. heads being 180 degrees apart from each other this emulate 60 cycles. head speed is only 29.5 rpm or 30 cycles times two heads 525 lines emulates 60 cycle scanning speed which is the vertical sync source per frame which is are 110volt ac 60cycle here in the U.S.A.vertical locks to 60 cycles to prevent picture rolls up or down.



some times a vcr will unload cassett in rewind mode the vcr thats noted for this is rca.this is caused by serveral malfunctions first is the threading belt does no position mode selector switch attached worm gear or shaft and its not in right mode or bearly in mode.grease the factory to lub these gears gets old creammy and thick slows down gears or drag and belt slips while threading.clean off some of the grease use some 3-1 oil just a dot.also rewind clutch will disengage if tape slack a little it will unload in rewind.under take up reel is an l-e-d sensor to detect reel movement if reel hesitates it will unload in rewind.also dirt or grease gets on l-e-d foil reflector under the take up reel vcr will eject in rewind.if you main drive belt slips in rewind it will eject. and findly system control chip for the mechanics over heats or going bad will eject in rewind rca .emerson.symphonic.sylvania.anything by faniua of china are prone to do this just to name a few vcr.

Post edited by: hobbist, at: 2008/05/07 16:20

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Post edited by: hobbist, at: 2008/05/07 21:38

a standard four head vcr lays five signal tracks at the same time C.T.L (CONTROL TRACK LOGIC) along the top edge of the tape. then two video track helico scanned video heads are tilted angle to right the video track is scand at an angle also the head spins aganist the tape movement head spin counter clock wise tape comes out for supply reel on left side of the cassett and takes up in the right side of the cassett.and at lower edge of tape two audio tracks.track one is on the very edge of tape track two is farther in from edge of the tape a few centimeters.between the two video tracks theirs a guard band track.the guard band is used sometimes in stereo hi fi four an audio track.will cover later.

C.T.L track is simular to sprockets on old movie film a ditigal signal in inplanted just above odd scand numbers 3,6,9,12, of the 262.5 half frame lines to sync the tv to the vcr from correct frame rate.the second head for the even scand numbers 2,4,6,8 other half of the frame rate lines.this head lines up automatically.remember the scand rate in the U.S.A is 525 lines on a standard analog crt.to be continue.

Post edited by: hobbist, at: 2008/05/08 18:59

Post edited by: hobbist, at: 2008/05/08 20:25

the helico scan at an angle to try to give the longest track possible to accomadate as much of the 262.5 lines as possible not all of the data is capatured head conditions tape quality and other factures all play into this.last 8 dots on each scand is reserved for horizontal and vertical sync pulses before heads leaves the edge of tape that goes for both heads so theirs not much tape in one half inch width tape.if you notice picture quality seems better in sp speed then in ep speed.know for the purpose of explaination bear with me.in ep speed the tape track for video is shorter using a degrees let say in ep the track is laid about 4 degrees the 262.5 lines data the second head comes by and lays the other half of the 262.5 lines data making a full frame of 525 lines of scan in so many centimeters lets say 2 centimeters.know we switch to sp know track is being laid about 6 degrees tape is moving faster laying a longer track about 9 centimeters more video info is being put down increases video quality more data color increases detail in picture improves the draw back is run or record time is shorter because tape is running faster so on short movies lets say two hours you use a four hour tape so and so forth. three hour movie use a six hour tape. to be continued.

Post edited by: hobbist, at: 2008/05/08 21:08

Post edited by: hobbist, at: 2008/05/08 21:14

C.T.L HEADS AND AUDIO :
as tape leaves video heads to the right side around threading post go to take up reel tape passes through the audio head and control track logic or C.T.L on the right side of tape transport..the audio heads are two slots at the bottom and the single head slot at the top is C.T.L. of the same head assemble.left channel is recorded at the very bottom of the tape and the right channel is few nano meter just from the very edge at the bottom.this head operates just like a standard audio ihead in a stereo deck except for C.T.L.CONTROL TRACK LOGIC is DIGITAL SIGNAL to position video heads with tape an set correct speed relation ship tape to head spin speed.this head is the one that tape slugs and dirt will cause tracking errors and audio problems clean on regular bases and tape guides also will cause tape sticking if dirty.to be continued.

these editiorals info is written for the common person on the street.theirs more to vcr serviceing then is mention.their is things as tape guide alignment their is vedio head mechanical and electrical aligment.tape back tension brake aligment etc.this requires an o-scope special scales for brakes and special alignment tapes with signals is not avaibles to the street.so with that said i was just giving some ideas what to look for. to point out for regular owners and some owners may be able to figure out solve for them selves.know my final entry to this subject on tape loaders and on no rewind no eject and no threading will be continued it the next editioral.to be continued.

Post edited by: hobbist, at: 2008/05/09 13:39

Post edited by: hobbist, at: 2008/05/09 13:40

Post edited by: hobbist, at: 2008/05/09 13:43

the first thing you do is remove is the cover look for grand childern contribution such a toys ,penicels,crayons.and penut butter and jelly sandwiches,cookies i am serious i have seen this in my career.clean first.the next thing is you will have to shade the in side with a peice of paper or a book the light will effect the sensor in the deck and cause it to eject.so lets begain the first thing insert tape watch loader should accept and set down in machine.then comes the tape out and just before reaches video heads they should start to spin.then on the right side the pinch roller should start moving into position capstan motor should be spining.click should be vedio and audio.this functions are control by:

a:loading motor
b:loading belt
c:mode selector switch

then the take up reel should be moving this controled by:

a:capstan motor
b:main belt
c:clutch assembly between reels tables

if the machine ejects

a reel table take up clutch
b:belt broke or loose or slipping incorrect speed
censors under take up reel is dirty or burnt out
d:or one of the end of tape sensors is bad

out side loader on both sides their is two l-e-ds emitts light to the center post looks like a crystal. this conducts light to a infra sensor on main board .in some vcrs the sensor is in the center infra receivers out side loaader.when cassett in and down pin holes line up for the sensors sometimes grease from loader blocks these holes.can not sense tape.
the other possible is mode selector switch is not in correct position.this is caused by threading belt slipping lubcration on mechanics or weak motor or incorrect b-plus voltages.

also tape slack from take up reel can cause eject.either capstan motor main belt or worn clutches or b-plus voltages.


the mechanics in all machines are controled by system control micro for tape transport functions.so do this:

first clean,check belts.oil mechanics clean off old grease.clean tape path heads, guides,remove insects,mice,spiders,cob webs,lint etc. i a not kidding i have seen this also machines stored garages and barns then brough in for repair after being their for a few years.i had one with a baby mouse inside.


this ends this serious on vcr i have given basics this should give you the ability to fine you problems.i will be adding to these editiorals as i think of additional info so you want to check these know and then.feel free to ask questions if needed.i am ill and if i am still around i will answer.

Post edited by: hobbist, at: 2008/05/09 15:24

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Post edited by: hobbist, at: 2008/05/09 16:58