Cleaning VCR Heads
Its very important more now than ever, to maintain your vintage video recorder heads. Replacements are nigh on impossible to source, your main option being to purchase donor machines. These too may have worn or contaminated heads. Below are the steps necessary to ensure you clean your video heads properly and safely.
Important to Note: Warning
Extreme caution is advised when cleaning heads, particular care with older VCR’s like the early versions.
One reason that can be attributed to poor head cleaning, it is that technicians are applying insufficient pressure to the head face during cleaning. It has been drummed into us that the head face should be cleaned very lightly, (if at all) this is true but this can lead to not applying enough pressure to get a good clean. Newer VCR’s had more robust modern heads which were glass infilled; the head face should in fact be cleaned by pressing firmly (but carefully) against the drum/head. The older first generation VCR’s require a lighter more careful approach. It is obvious that damage can result to the head if the utmost care is not taken.
Recommended cleaning method
- Chamois Leather Sticks or Chamois leather cloth
- In the absence of the above, A4 Paper Strips
- Isopropyl Alcohol (IPA)
Warning Note: Never under any circumstances use a ‘cotton buds’ (Q-Tips if you’re across the pond) to clean the video heads.
1. Gain access to upper-drum assembly area.
2. Inspect for the following:
a) Damage to video heads and scores and scratches on the drum surface. Replace upper-drum assembly if
b) Tape debris around tape guides and upper/lower drum area. Remove if present.
3. Using the sticks or wrapping the chamois leather firmly around your index (pulling it tight) or holding an small A4 paper strip.
4. Moisten the Chamois or paper with the cleaning fluid.
5. Clean the video heads and surrounding area by holding the Chamois/Paper against the upper drum where the heads protrude. Manually rotate the upper drum in a clockwise direction whilst maintaining steady, uniform pressure. Rotate the drum six to seven times. Do not clean in a vertical direction. Only apply sufficient pressure to the upper drum to be able to feel the video head profile through the chamois/paper
Note: Do not attempt to clean the heads whilst the drum is in full drive rotation.
6. Using a dry clean chamois or paper strip, repeat step 5 to dry and remove any oxide dust which may remain.
7. Check the performance using a suitable test tape and, if necessary, repeat the cleaning procedure. If results are
still unacceptable after the third cleaning attempt, it may be concluded that the head is unsalvageable and
must be replaced.
Symptoms of video head contamination, wear or damage
|‘Snowy’ picture, picture visible in background.||One head giving low/no output because of oxide contamination, wear or due to a cracked ferrite.|
|‘Snowy’ picture, picture obliterated.||Both heads giving no output. Causes as above.|
|Playback lacking LF & HF with noise.grain in the background||Worn or oxide-contaminated heads giving low FM outputs.|
|Poor ‘search’ (on models with it) pictures and excessive noise bands||Worn or oxide-contaminated heads.|
|Black/White streaking||Worn or oxide-contaminated heads|
|Frame bounce/variable noise bands.||Worn or oxide-contaminated heads|
Maintaining good head performance
The main principle in obtaining good quality record and playback signals is that of maintaining good head-to-tape
contact. Two important factors in maintaining this relationship are:
a) Head protrusion
An unused video upper drum assembly will have a video head protrusion of 45-55uM (see below). With use, the protrusion will be reduced to a limit of 20-30uM before the noise content in the picture becomes objectionable. The reduction in head protrusion can be displayed on an oscilloscope as a reduction in the FM output level. It should be noted that the signal to noise performance can be affected by scratches and chips to the head face before any such reduction in FM output is noticeable.
b) Video head cleanliness
A major cause of high noise levels (reduced or no FM output from one or both heads) is oxide contamination on the head face area. The accumulation of debris on the head face, or surrounding metal work, acts as a buffer or insulator between tape and head resulting in reduced pick-up and loss of FM output.
The oxide accumulation on the head face increases the friction between head and tape, resulting in an increase in head operating temperature and in the oxide being baked on to the head face. In most cases where this has occurred, two to three sequential cleaning operations will be required before the video head will perform normally once again.
The, taken from life, examples of contamination illustrated above, together with many similar specimens, have been successfully reclaimed by energetic cleaning.
Utilising a high powered microscope can help show a high degree of video head condition, of which the illustrations below are typical and which were the actual state of three heads examined.
Never, ever use cleaning tapes, either wet or dry, these are to be avoided at all costs. Ignore this advice at your peril. Replacement video heads are pretty much unobtanium now. Don’t say you have not been warned.