DIRTY VIDEO HEADS –

THE FULL STORY

Although now considered to be 'old technology' today, the VCR or Video Cassette Recorder, was a widely used piece of home entertainment equipment. There are still many in use today and the following article, although posted many years ago, is retained as it may be of assistance to users. 

About 25% of the Video Cassette Recorders (VCRs) received for repair come to us with the fault listed as no picture or snowy picture on playback. This problem is frequently caused by "dirty heads". Dirty heads, or to be more accurate, CLOGGED VIDEO HEADS usually results from playing a defective tape in the VCR.

 There are two video heads used to record or replay a picture. The heads are mounted on a polished aluminium drum, which rotates at high speed against the surface of the videotape. One of the two video heads is always in contact with the surface of the videotape.

What goes wrong:                                                                                                                                                                                               

 If the tape being used is defective in any way - this could be a crease, a grease spot, or the tape might be just plain worn out - some of its oxide coating may be deposited onto the video drum and the tiny video heads mounted on it. This material can clog one or both of the video heads, which will cause the picture to become snowy or disappear altogether.

Tapes:                                                                                                                                                                                                             

 Firstly it must be recognised that tapes wear-out. The oxide coating on the tape can start to peel off. This can happen due to moisture, age, rough handling and of course continual playing.

Moisture:                                                                                                                                                                                                     

 Because the video drum is very smooth, any form of dampness will cause the tape to stick to it. This results in the oxide coating being stripped off the tape by the rotating action of the head drum. The oxide actually sticks to the drum and of course the video heads. This will happen instantly. Most VCRs have a moisture (dew) detector to prevent the VCR from playing if the head assembly is damp or cold.

Again, this will cause the tape to adhere to the video drum, with similar results to above.

Damaged tapes:                                                                                                                                                                                                 

 Any tape that has been jammed or damaged by a VCR should be discarded immediately. The cost of a new tape is quite low compared with the cost of repairing your VCR. Damaged or creased tapes will not sit flat against the video drum; the oxide on the raised creases may be scoured off by the rotating action of the video head drum, this will generally cause head clogging.

Children’s tapes:                                                                                                                                                                                             

 These tapes are often much loved and played over and over. Tape wear can lead to the oxide coating peeling off. It is also our experience that many of these tapes, even though the purchase price is high, are recorded onto poor quality blank tapes.

Hire tapes:                                                                                                                                                                                                       

 These are the most frequent cause of dirty heads. Very few video rental shops inspect or clean their tapes between rentals. If the customer who had the tape before you had a dirty or poorly maintained VCR, it is quite possible that the tape may have picked-up dirt or grease from that VCR. When played in your VCR, that tape may transfer the dirt or grease into your VCR, which can clog your video’s heads. Old hire tapes (often hired out for a $1.00 a week) are particularly suspect, many of these are in very poor condition, and well past their useful life.

Cleaner tapes:                                                                                                                                                                                                 

 These are great for emergencies and will often clean the heads and get the VCR operating again. They generally clean only the rotating head drum, and will not clean the whole tape path. Over-use should be avoided, as most are somewhat abrasive and can cause premature headwear. Care should also be taken, to ensure that the brand of head cleaner is compatible with your VCR. Some brands of cleaner tape may jam in the VCR. If in doubt, check with the maker of your VCR for his recommendation.

Care of tapes:                                                                                                                                                                                          

 Videotapes should be kept free of dust and moisture, and should be placed back in their protective covers. They should never be placed where they can come into contact with drink spillage, food particles, moisture, children’s fingers, etc.

 If the picture starts to break-up, lines appear, snow comes and goes or the picture disappears into snow, the tape should be considered suspect and removed from the VCR

The picture was good one minute and quick as a flash it went snowy:                                                                                 

The rotating video heads have become clogged. The tape passing over the rotating head drum has deposited oxide onto the video heads and they are no longer able to ‘read’ the videotape.

I tried another tape, but the VCR still wont play:                                                                                                                                 

Once the heads have become clogged, they can no longer either record or play, regardless of the tape.

If you haven't had problems until recently:                                                                                                                                                       

Your tapes may have become contaminated. This can be an on-going problem often resulting from the use of a single dirty or damaged tape (often a hired tape). It happens this way … oxide or grease from the defective (hired) tape deposits itself onto the video head drum. Another (perhaps new) tape is played in the VCR to see if it will work, which it wont. The VCR is taken in for service, it is cleaned and tested and returned as being OK.

 Now the problems start … that second tape is used again in the VCR. Remember, this was a new tape, so it should be OK. But the original tape that was used deposited muck onto the video head drum and that new tape was played in the VCR BEFORE it was cleaned, some of the contamination was transferred to the new tape. That new tape has now contaminated the video heads again.   If you get into this cycle, the only answer is to have the VCR thoroughly cleaned and then start off with some new tapes.

Remember, a contaminated or faulty tape can cause the heads to become clogged IMMEDIATELY the faulty section of the tape comes into contact with the rotating video head drum.