Television and Video Advice
January 2009. Welcome to our cockamamie video hints page. Please bear with us as we move over from the former AOL Hometown; some links may take awhile to get fixed.
Ideas, hints and inside information to help everyone better understand video and electronics and help choose a TV set or other video equipment. Comb filters, DVD, HDTV, resolution, remote controls, we try to present it in an easy to understand manner.
All parts (c) Copyright 1997-2009, Allan W. Jayne, Jr. unless otherwise noted or other origin stated.
Major Video/TV/Computer Topics:
How This Web Page Got Started (2/99)
Glossary of Video Terminology
My Movies (list) (3/02)
Some Frequenly Asked Questions
External Doubler Good As Progressive DVD Player (4/02)
Anamorphic DVD (9/98)
Audio Cables for Video? (3/00)
Audio/Visual Receivers (7/98)
Video Bandwidth (for 480p, HDTV) (10/01)
Buying a TV, My Wish List (2/99)
Buying a VCR, My Wish List (2/99)
The DVD Chroma Upsampling Bug (11/01)
Color Resolution (10/98)
Commercial Skip Feature Shortens Life of VCR (2/99)
All About Component Video (2/01)
Composite Video History (6/01)
Connecting Up Your Equipment (7/98)
What is a Digital TV? (3/02)
Don't Drill Hole In Tape Cassette (8/98)
Dot Pitch Limits, RPTV's Have It Too (5/99)
Downconversion and Scaling, the Lowdown (5/99)
Understanding Encoding and Decoding (7/98)
What is a Fresnel Lens (2/00)
PC Hard Drive Partitioning
Irritating Problems with VCR's (10/98)
HDTV (High Definition) for You and Me
Buyer Beware -- Non Hi-Def HDTV sets (1/06)
HDTV Improves Diagonals Over Details (2/99)
HDTV Converter Tuners (set top boxes) (10/99)
HDTV -- 1000 x 1000 Pixels For Now (10/00)
Should I Buy 1080p? (1/06)
History -- Electronic circuit building toys
What Is A Home Theater? (8/99)
Make Sure All Jacks Work (7/98)
Line Doublers (5/99)
Move TV Before Calling Serviceman (3/00)
Nyquist Theorem Fallacy (2/00)
Progressive Scan (5/99)
Progressive Scan DVD Players (2/00)
TV Resolution, Explained
Rewinders for Video Cassettes
(Front) Projection Screens
Souvenir Videos, Correct Format
What is a Tint Control? (11/99)
Universal Remote Controls
Wall and Desk Brackets (avoid them)
Wide Screen Movies
Other video web sites and forums
Articles on other subjects.
Why Does This Web Page Exist?
In 1993 I worked for Digital Equipment Corp. (now part of Hewlett Packard Corp.) There was no Internet as we know it but DEC had an on line forum for employees only where people asked and hopefully got answers to questions.
I saw over and over such questions as:
"When I play a wide screen movie half the screen is black. I need to call a repairman."
"This TV is advertised as having 800 lines of resolution. But I thought NTSC was 525 lines."
I started answering some of these questions in that forum. When I heard of the Internet I promised to get some of those essays published for the benefit of everyone. I think the first message I wanted to get across was this from a technical book on video: "Lines of resolution is correctly measured in the largest perfect circle that fits in the space we are talking about. (For a standard TV screen that represents 3/4 the width.)".
Answers to questions on other topics followed -- health, travel, family relations to name a few. Also I have started to editorialize on some of the current events of the day Of course I don't agree with everybody on these. The web pages you are looking at is the result of this project.
UHF/VHF Antenna for HDTV
In many cities, some TV stations will be broadcasting digital and HDTV shows after February 2009 on actual channels 2-13, which are VHF channels. Therefore you may need an antenna for both VHF and UHF (a regular antenna, that is). This is true whether you have an HDTV set with built in ATSC tuner for digital broadcasts, or an ATSC set top box feeding an older TV set. (If you use cable TV or satellite TV you probably don't need to do anything come February 2009 although some cable companies may require that you use a different cable box that they rent to you.)
Bad Picture? Move the TV
Before you call the serviceman, try moving the TV to another place in the room and also face it in a different direction.
A reader of Home Theater Forum wrote in their Advanced Topics, "I moved to a different apartment and all of a sudden there was red and blue smearing in the picture even when viewing VCR tapes. They took the set to the shop several times and the problem never showed up there."
It turned out that there were some electrical cables on the other side of the wall causing interference, not with reception but with some of the TV's internal circuits. Broadcast signals went through the affected circuit and were smeared but so did the VCR playback. In this instance the DVD player was connected so as to skip the affected circuit so it played back clearly. So the TV set suffered the jostling of several trips to the shop for no good reason.
By moving the set to a different room or at least to a different place in the same room, and also turning the set to face a different way just for a few minutes, you can sometimes get an idea of whether it is the set that is at fault or something else in your home or a neighboring apartment.
Washing machines, cable TV junction boxes, lawn sprinkler control boxes, neighbor's TV's or stereo sets, etc. could all be causes of interference.
We are not absolutely sure that modern plasma and LCD TV sets are immune from interference from nearby electrical equipment.
Beware Using Commercial Skip On VCR
If your VCR has a "commercial skip" feature for recording, using that feature may shorten the VCR's life.
For some brands of VCR's the commercial skip works this way: After the VCR records the program, it rewinds, "plays the program back to itself", and records flag signals on the tape where it thinks commercial breaks start and end. This uses up the finite hours of life of the tape heads and also forces you to do the head cleaning procedure more often.
When you play the tape, the VCR automatically fast forwards through the sections of tape it marked off, just as you might otherwise do manually with the remote control.
The VCR has a way to turn off this feature when you don't want to use it. Commercial skip is not foolproof in finding and marking all of the commercials and it may also skip some program material here and there.
Buying a TV Set
For those of you planning to buy a non-HDTV ready TV set, here is my wish list for features. When shopping, bring this with you as a checklist. Try out the TV in the store as much as possible rather than bring it home first. (For HDTV, all of the items below still apply, click here also.)
1. S-video input jack as a minimum. Component video input jacks are desirable for future planning. even though you pay more for them and opinions on improvement in picture quality range from "hardly noticeable" to "noticeable but small".
2. Irritating problem to avoid: Inability to select programs coming in the composite jack and the S-video jack, (and the component video jack cluster if any) without having to crawl around back and unplug the other cables. If the set has several banks (groups) of jacks with a composite jack in each bank, an S-video jack in most banks, etc. it does not have a problem here. If there is only one jack of each kind, try it out in the store using different sources plugged into the jacks.
3. Comb filter without lots of dot crawl. This requires at least a "three line 2D" or "three line adaptive" comb filter. The "3D" comb filter is generally better although more expensive. There should be almost no dot crawl going across, very little going straight up and down. (Very few comb filters can eliminate all the dot crawl along diagonals.)
4. For a 4:3 aspect ratio set, the ability to reduce the picture height to 16:9 easily including any tweaking such as pincushion distortion or convergence. Try it out in the store.
5. Ability to fine tune picture width and height to set the desired amount of overscan.
6. No more than one scan line's worth of convergence error anywhere on the screen. Examine up close, using a magnifying glass if desired.
7. Accurate interlace, even lines almost centered between the odd lines. Examine up close, using a magnifying glass if desired.
8. Picture does not expand noticeably or bounce when the amount of light colored material increases (power supply regulation). Try going from a really dark scene to a really light scene, also from scenes with different contrasting colors predominating. The solid color screens at the end of the Video Essentials disk are good to try. You may be able to see this just by watching the program already playing on the TV in the store.
9. Black does not become grayish when the amount of light colored material increases (poor black level retention). This can be tested by setting the black level for a dark subject so that scan lines don't show at all, and then check to see if scan lines appear in the black areas.
10. Above minimum color resolution using composite video jack. The only test I know is on the Video Essentials disk, the Snell and Wilcox zone plate. There should be a lot of red and cyan throughout the "1.0 MHz" stripes at the lower left center. If there are black gaps among the stripes at lower dead center, they should be much narrower than the blue and yellow stripes. (Using S-video jack and DVD version of VE, there should be lots of red and cyan in the 1.5 MHz stripe set.)
11. Geometric uniformity, that is no gradual stretching or squishing in different places about the screen especially at the edges. On poor quality TV sets the picture is squished at the edges (horizontal and/or vertical sweep waveforms rounded off) and lots of overscan is used to get those parts off the screen.
12. Irritating problem to avoid: Aspect ratio locked on a particular setting (e.g. 16:9) when certain inputs (e.g. progressive scan) are being received.
Also see Consumer Reports magazine for other desirable characteristics of TV sets.
While we are on the subject of buying a TV, when you do bring one home, first thing you should do is turn the contrast down to a third of maximum. This prevents burning the screen without your knowing it.
NTSC (U.S. standard) Video Resolution -- Numbers to confuse you with
We have expanded this topic and moved it to a new page. Click here.
(The page URL is http://members.aol.com/ajaynejr/vidres.htm)
Proposing a New Standard for Resolution (10/98 revised 6/99)
A new school of thought has adopted a two number resolution rating for pixels across the entire screen and pixels vertically. I suggest the term "MPA" for "maximum pixels across" to distinguish the numbers from "TV Lines" which imply the first 3/4 of the width of a standard TV screen.
In addition I have added the "a" suffix for analog, and "d" for digital. NTSC examples:
VHS (tape): 320a details across., 482d scan lines vertical
Broadcast; cable: 440a across., 482d vert.
Laser disk: 560a across. by 482d vert.
DVD (4:3 and 16:9) (approx) 720d across by 480d vert.
1080i HDTV 1920d by 1080d
VGA computer 640d by 480d
The significance of "maximum pixels" is that in analog reproduction, picture details don't have to be an integral number of pixels in width and do not have to be aligned with an imaginary grid with the published number of pixels. For analog reproduction, resolution may as well be rounded to the nearest ten "pixels" because it reaches its limit by having the adjacent fine details faded to subjectively nearly indistinguishable shades of gray.
All video uses horizontal scan lines so the picture is always pixellated, or digitized, in the vertical direction. For this new suggested standard, therefore, the vertical resolution expressed as number of scan lines always has the "d" suffix.
An advantage of using the entire screen width is that we don't have to state the aspect ratio. However the traditional "lines of resolution" measured across the largest circle that fits the space makes it easier to compare the resolution of small portions of a picture.
We already have a convention for interlaced versus progressive scan. For example, NTSC, which has approximately 480 illuminated scan lines (out of 525) and even-odd interlace, the term 480i has been used. For VGA computer screens which have 480 pixels vertically and the scan lines are not interlaced, we have seen the term 480p, the "p" stands for "progressive scan".
How does analog relate to digital? Today, nobody agrees. The only published formula I have seen so far is to multiply the digital number of pixels or lines by 0.7 (an "extended" Kell factor) to get the equivalent analog "lines of resolution". Applying this Extended Kell factor, 480 scan lines equals 337 analog lines of resolution vertically. DVD resolution as 720d by 480d would be equal to 504a by 337a. Actually I think the Extended Kell factor for moving subjects in video is around 0.85. Extended Kell factors are derived by having people look at test patterns with alternating dark and light lines and making subjective evaluations.
Of the 525 lines in a video frame, 480 are used to make the picture. On each line, laser disk claims 425 lines or dots of resolution. Since, correctly, lines of resolution is computed in the largest perfect circle that fits in the 4:3 aspect ratio screen, we multiply by 1.33 to get the number of pixelsborder to border. We can think of the picture as being 480 pixels (picture elements, tiny rectangles) high by 565 pixels wide or 271200 pixels in all. Let's call this size B. For "memory" the number 512 is more of a standard number so let us also call a 512 high by 512 wide memory a size B; it is close enough.
But if you use a 271200 unit memory to hold the picture for a still frame, it will look worse compared with the picture being refreshed constantly from the spinning disk. In analog video, a tiny dot can occupy a fractional pixel position, say 43-1/3 horizontally and storing the picture in memory requires that that dot be moved to one side or the other (digitized). Words and text in the subject matter are degraded.
You can think of the picture as being projected on a large silk screen, where each hole has to be all one color, if a spot of color wants to land between two holes, it has to be moved to fit entirely in one hole.
When a picture is displayed on a video screen as a matrix of pixels (is digitized), the lines of resolution rating according to some experts is approximately 0.7 (called a Kell factor) times the number of pixels across the largest circle that fits in the screen. A video motion picture of a moving test pattern will show the blur out point averaging at about that value on the scale. In order to "have 425 lines of resolution" there must be 607 pixels across the largest circle (807 pixels border to border). Now we need 387360 units in the memory. Call it size C.
Putting the subject on video already digitized all vertical detailing onto the 480 scan lines resulting in some distortion from the original scene. Applying the Kell factor, the vertical resolution is said to be 336 lines. Adding memory units to handle more than 480 pixels vertically gains you nothing.
I said that the blur out point averages 0.7 times X pixels on the resolution test pattern's scale. A video scene may show the man in a striped jacket but a still frame selected from that scene may have the jacket blurred to solid gray because the pixels straddled the stripes halfway. In the next frame the man may have moved slightly so the pixels line up better and the jacket shows as striped. In order for the blur out point to never be less than X, we must have X at least twice the "number of lines we want to have". For 425 lines we want 850 pixels wide in the perfect circle (1130 pixels border to border), or (times 480 scan lines high) 542400 units of memory in all. Call this size D.
A size C (see above) memory will hold a much more accurate digitized picture compared to the original analog video frame than a size B. Most people can't see the difference if we go the extra distance to the size D memory in a disk player or VCR. Except in the cases of moving striped objects shimmering as they go in and out of gray blur in some scenes, you would need a magnifying glass to see defects. The value of the larger and much more expensive size D memory comes in mastering. So long as the horizontal and vertical pixel format stays the same, a digitized image can be copied repeatedly without degradation. But if the picture is redigitized into a different sized memory, degradation is severe with just one copying using size C or B memories. Using size D memory during mastering, a few memory size changes plus the final transfer down to size B or C in the final consumer product can be tolerated.
What is size A which I skipped up unti now? Here I consider it a "field" memory, that holds only the even scan lines or only the odd lines -- half the picture. A 131072 unit, or 256 (high) by 512 (wide) memory would fit my description of size A, and it is very common on today's high end laser disk players that do CLV still frame. Its resolution is 168 lines high by 269 lines wide (the horizontal is the same as size B).
Color horizontal resolution for all NTSC video sources including laser disk is much worse, never better than 120 lines and at best 50 lines (in the largest circle) when greens next to purples are involved. Tiny spots of color horizontally will often be wrong, smeared too wide, or maybe have gray, black, or white substituted. Notice especially that small colored lettering tends to have black shadows. Multicolored detail such as a flower bed not close up looks decent in a video motion picture because from field to field, 60 per second, a different color may win over a particular tiny spot on the screen. On a still frame, multicolored detail will be very grainy and incorrect looking. The limitations of color resolution may make it difficult to see the difference between having a size C memory versus a size B memory but I would wait until something at least halfway between B and C became available.
Units of memory here are arbitrary and don't stand for bits or bytes. The are just used to differentiate the relative amounts I called A, B, C, and D. Resolution is not as good as described above if invisible format data at the end of every line and also the invisible format lines (#481-#525) between fields have to share that memory.
Digital Video Disks (DVD's) officially have picture dimensions of 704 to 720 pixels wide by 480 to 496 pixels high. Using 480 pixels high matches the 480 scan lines that actually hold the picture in a standard NTSC video frame. The 720 pixels wide actually matches one of the digital video standards (D1) used in video production for several years before DVD was introduced. Some data compression techniques used for DVD work better with a 704 pixel wide video frame. Click here for more information.
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Some Other Reasons For Resolution Less Than Expectations
1. Program material. Not all broadcast programs have the full broadcast resolution. News crews nowadays sometimes use home grade VHS camcorders with the usual 250 line (or maybe less) horizontal resolution. Video cameras have shutter speeds just like film cameras, and if the shutter speed is too slow, moving objects will be blurred.
2. Bad interlace. The even lines should land between the odd lines on the screen. Occasionally a badly adjusted or poorly designed TV set will have the even lines landing on top of the odd lines and this cuts the vertical resolution in half.
3. For camcorders, sometimes the optical pickup element is divided into pixels horizontally as well as pixels vertically. A 512 by 512 pixel pickup will have at most 512 times the Extended Kell factor (subjective but approx 0.7) lines of left to right resolution when dots cannot occupy fractional pixel positions on a line. The result of 358 has to be multiplied by 3/4 to take into account fitting in the largest perfect circle that in turn fits in the 4:3 aspect ratio picture. The horizontal resolution is therefore 270 lines which incidentally is all a standard VHS tape can accommodate. Some camcorders only have a 256 by 256 pixel pickup so that pairs of even and odd lines are always the same, losing half the vertical resolution as well as having half of the horizontal resolution compared to a 512 pixel wide pickup.
4. Less than top quality electronics. Even back in the days of black and white TV, over 75% of the TV sets made had no more than 250 lines of horizontal resolution because they did not have adequate frequency response to use the entire 4.2 MHz video bandwidth where the finest details are out at the 3.2 to 4.2 range. When color information was put in the 2.5 to 4.2 range (color carrier at approximately 3.58 MHz) this vast majority of sets did not experience any interference. More expensive B&W sets showed a fine grained but noticeable dot pattern somewhat like silk finish photographs when receiving color broadcasts.
5. Poor convergence. It is difficult to get the three electron beams that produce red, green, and blue on most TV sets to match up at all points on the screen. An error of one fifth of one percent of the screen height puts the errant beam on the next line, enough to cut the resolution in half. Poor convergence shows up as color fringes around objects in a black and white picture (turn the "color" control to minimum to demonstrate this).
6. Dot size and dot pitch. For small consumer grade TV screens, dot size is not proportionately smaller. A seven inch diagonal screen has dot clusters about 1/2 of a millimeter in size, or 215 clusters across in the largest circle (4.2" or 10.75 cm) that fits in the screen. Although smaller dots can be reproduced subject to the capabilities of the electronics and other components, they will not be white if the beam does not hit all three colors red, green, and blue. A 20 inch screen has dot clusters about 4/5 of a millimeter in size, or about 375 clusters across the largest circle that fits. Even today (1998), small (under 14 inch) consumer grade color TV sets do not have the fine 0.28 mm and smaller dot pitches found on good computer monitor screens.
7. Electron beam spot size. If the beam is not finely focused, the image is of course less sharp. Some TV sets have a sharpness control up front; all other sets have a focus control in back. It is not easy to achieve the finest focus over the entire screen surface and it is acceptable if the spot becomes twice the size or slightly elongated at the screen edge. Getting acceptable brightness also prevents making the spot too small and this makes it more difficult to get a sharp picture on a small screen.
Color horizontal resolution for broadcast, laser disks, and any source materal fed in through a composite video input is never more than 120 lines, and is as low as 48 lines for some colors. All consumer VCR tape formats have theoretical color resolution of less than 40 lines due to bandwidth limitations. In actual practice it is likely to be around 25-30 lines given manufacturing cost cutting. If the adjacent thin colored objects at least alternate light and dark, they will still be resolved (be distinguishable) but they will be discolored. More on color resolution, click here.
Buying a VCR, My Wish List
Before buying a VCR, try it out in the store, including setting the timer to tape five minutes' worth of a program five minutes from "now".
1. No menu should ever change by itself without your pushing a button on the remote. Here is a particularly irritating problem:
1a. When I am trying to verify what programs are in its memory (program review) it does not give me enough time to read the display before it flips to the next one and then the next one. A few years ago Toshiba had the Consumer Reports top VCR ranking. Unfortunately that model had this problem and I therefore passed it up in favor of number six on the list.
1b. (Related to the problem above) When I no longer want it to record something and I press the delete or cancel key it might wipe out the wrong program. This is because I am supposed to display the program I want to delete but it flipped to the next program before I could press the delete key.
2. Displaying the channel it is on while recording. Just in case I made a mistake programming it just before the show started and want to hurriedly correct it..
3. Let me modify a memorized program without deleting it completely and starting over. For example the football game runs overtime and I want to record "60 Minutes" starting and ending half an hour later for just that week, then change it back.
4. It should not grind the head wheel against the tape after I press "Stop". This forced me to eject the cassette and then the tape counter position was lost and went back to zero.
5. Front panel controls for common functions like channel selector or fast forward. so I don't have to go find the remote.
6. Record button should be away from play button, to avoid accidentally eraseing tapes.
7. I forgot to turn it on and put in the tape until after the program started. It should go into timer recording to pick up what is left of the program, I don't want to have to manually press Record and when the show is over manually press stop. I don't want to cancel the program from memory and reprogram it for the current recording, then reprogram it back to the original start time for next time.
8. Backward single step and visible (scanning) rewind. Saves the awkwardness of stopping, rewinding, and going back into play if I wanted to still frame and missed the spot.
9. Ability to record for a specific number of hours or minutes starting from "now" with a simple button pushing sequence. For example if I press the button once, it will start immediately and run for 15 miinutes, if I press the button a second time, the recording time extends to 30 minutes and so on.
10. On screen tape counter doesn't keep disappearing, forcing me to keep pressing to Display button on the remote to see where to stop the tape.
Universal TV Remote Controls
1. The models that are easiest to set up (preprogrammed) may not include all the features of your VCR or TV.
2. Some models (learning) let you arrange the TV and VCR functions and features among the buttons in any order you wish, although it may take awhile to set them up.
3. I recommend models with both preprogrammed and learning capabilities.
In addition to the convenience of only one remote control unit sitting on the coffee table, the universal 'remote' gets the day to day wear and tear while you put aside the original remotes for safekeeping. If an 'original remote' breaks, replacing it is generally expensive, and sometimes almost impossible if the set model was discontinued.
Every universal remote has several memory banks, one for your VCR, one for your TV, etc. A switch in front selects which bank is in effect at any given time. The more banks, the more different devices you can control with the same remote. If there are lots of keys, you may be able to have two sets (e.g. TV and cable box) controlled by the same bank, so you end up changing banks less often.
If two or more sets actually use the same infra-red codes, for example are the same make and model, the universal remote will not solve the problem of trying to activate one set and undesirably activating both.
Some sets require hold down repeat, or 'typamatic' capability. Some Panasonic VCR's advance the start time by only one minute per keystroke, or faster only if the key is held down.
Kinds of Universal Remotes
By entering, say, three keystrokes you set up the remote for your Sony KV18 or your General Electric MA-32, etc.
Advantages -- Only a few keystrokes to set it up for your sets.
Disadvantages -- Some functions require cumbersome and hard to remember multi- keystroke sequences, for example setting your VCR may require Gold (or 2nd), Play, Two to advance the start time one minute, or Gold, Play, Three, Three to pull it back two minutes. Some set functions may not be available at all.
Point the universal remote and the remote that came with your set at each other. Hold a button on the original remote and hold a button on the universal remote and that function is memorized by the universal remote. Repeat for each function.
Advantages -- (Usually) any key can be used for any function. If there are leftover keys, you can add a few VCR functions to the bank used for the TV, etc. You can put all the frequently used functions on one bank as opposed to assigning a bank to each set.
Disadvantages -- Takes longer to program; you have to "teach" each key.
3. Combination preprogrammed and learning.
Enter three keystrokes to program in most of the functions for a TV or VCR and then use the learning feature to assign additional frequently used functions to extra function keys provided.
Advantages -- Only a few keystrokes to set up most of the functions for your sets. Shortcut keystrokes can be added for often used functions via the learning feature. If there are enough keys, you can add a few VCR functions to the bank used for the TV, etc.
I strongly recommend the Combination remote. I have one of those, a Gemini MAC20, which costed about $15.00 at K-Mart and has three banks.
Things to Look For:
That you can try the remote out at home and return it if unsatisfactory. Once in awhile a specific function or even all the functions for a particular TV set doesn't work.
That there are enough banks for your sets (sometimes two small remotes cost less than one large one).
For preprogrammed remotes, that the makes and models of your sets are listed on the package and therefore available for use. If the remote is several years old or if your set is a new model, there is a good chance the remote does not have your set in its repertoire.
That if you have two TV's, etc. you can set up one on the TV bank and the other on the Cable box bank (or other unused bank).
Whether holding a key down will repeat that function, e.g. channel up or start time advance.
For learning remotes, that there are enough keys for the functions you use regularly (not all keys are 'teachable' on combination remotes).
That the remote has enough memory to hold/learn all the functions of all your sets.
That for sets with numeric keypads on the original remote and only channel up/down on the set front panel, the universal remote numeric keypad will work.
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1. Generally videocassette rewinders are very rough on the tape and can break it.
2. A VCR uses an electric eye to stop the rewinding before the tape hits the end. Almost all rewinders do not have an electric eye.
3. I do not recommend a rewinder that does not have an electric eye.
When the cheap rewinder slams to a stop at the end of the tape, it can also "cinch" the tape pack and cause a wrinkle that repeats for every revolution of tape in the pack for some portion of the pack. Sometimes such repeating wrinkles look like a waviness or a thin pie slice on the tape pack surface that can be seen through the window in the cassette.
Then when the tape is next played, such wrinkles may produce horizontal bands of snow that slowly move down the screen every so often.
If you make such a wrinkle when rewinding the tape, you have to wind it to the far end and then rewind it again, hoping that the wrinkle wasn't imparted with so much force or wasn't left there for so much time as to become permanent.
Some cheap rewinders have moving parts so poorly shaped or molded that the tape spools in the cassette wobble. This causes the edges of the tape to rub the sides of the spool and also puts unnatural stretching stresses on one edge and not the other. This also leads to wrinkles, this time one edge of the tape is wavy but not the other. I once dismantled a rewinder and carved off flash and burrs of plastic from the spindles to make the spools run true, and it was still necessary to slap the rewinder body after inserting the tape cassette to make sure the spindles engaged the spools correctly.
Not quite sure fire guidelines to tell how gently a rewinder stops when it is done rewinding the tape:
1. Try out the rewinder several times and listen as the tape comes to the end (or beginning). If you hear a thump before the button releases or the lid opens, the rewinder is probably letting the tape slam to a stop.
2. After removing the cassette, look in the right side window. If the transparent leader points right into the spool for having been pulled literally to the limit, that is what the rewinder probably did. If it appears that there is still a turn or maybe a half turn of leader left on the spool, the rewinder stopped in advance of the limit which is much better. Make at least three tries, if the tape was pulled to the limit on any try, the rewinder probably does not have a gentle stop.
3. If the rewinder has a window through which you can see the tape rewinding, simply observe as the rewinding nears completion.
4. Does the instructions or labeling on the box state the the rewinder stops before pulling the tape to the limit? Does it state the rewinder actually has an electric eye to accomplish this?
Don't Drill Hole In Tape Cassette
I would not advise the average viewer to drill a hole in a videocassette to fool the VCR into thinking it is High-8 or whaterver. It is too easy to get plastic crumbs or shavings inside the cassette where they will get on the tape and then carried into the VCR, gumming up the works and likely causing severe head damage.
But it is OK if you can dismantle the cassette first, do the drilling and scraping off the burrs somewhere else, and (can be difficult) re-assemble the cassette.
If you have dissassembled a cassette in the past and know that the hole is not near moving parts or the tape pack, you might be able to use a heated paper clip to melt away a hole of the proper shape and size. You would have to trim away a burr on the outside and be careful not to let crumbs fall inside.
Other selected web sites with video topics (subject to availability).
Crutchfield's Home Audio & Video Information Library
Columbia University Audio & Video Terminology
inSync -- Sweetwater Video Information
S.M.R. Home Theater
Video Bulletin Boards and Forums -- Ask questions and add comments.
Digital Theater Forums
Home Theater Forum
S.M.R. Video Forum
(subject to availability)
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All parts (c) Copyright 1997-2005 Allan W. Jayne, Jr. unless otherwise noted or other origin stated. All rights reserved.
We do not have experience with many specific makes and models of TV sets and other equipment and therefore cannot give you any recommendations on what to buy. While you may find useful hints on this and other web sites, we still recommend going through checklists that Consumer Reports magazine publishes from time to time.