TAPE PATH CLEANING
After many hundreds of hours’ use a video deck will be in need of cleaning and servicing. Every component that the tape contacts along its entire path is cleaned with alcohol, applied with a soft cloth or cotton bud as necessary. The inside angles of tape guides require special attention, since grease, oxide and other debris can build up there to upset tracking. The drum surfaces often develop patches of black dirt, most easily removed by scrubbing with a solvent- moistened cotton bud; this same agent can be used to clean out and polish the guide rabbet on the lower drum. The front surface of the audio/control head is treated in the same way, then polished off with a soft cloth. In some types of deck (that shown in Fig. 18.2 is an example) the audio-control head face is not easily accessible or visible. Here the use of a bent cotton-bud stick is recommended for scrubbing, and an angled dental-type mirror for inspection.
The capstan shaft will often be found to have built-up rings of encrusted dirt at points corresponding with the upper and lower edges of the tape ribbon; these can be difficult to remove, and are best tackled by soaking them with solvent initially, leaving it to soak in and soften the deposits while other cleaning is progressing; hard vertical rubbing with a cloth held between thumb and fore-finger will then prevail. The use of a fibre pencil (available from component distributors) makes the task of capstan cleaning very easy. The pressure roller requires similar surface treatment, though the process is easier. Do not apply any abrasive agent to the surfaces of capstan or pressure roller. Any defect in the pinch roller beyond the need for cleaning should be dealt with by replacing it with a new one; it is not good practice to attempt repair, refurbishment or lubrication.
Where a general service of the deck mechanics is required, variousother components need to be checked. Specific details of these depend very much on the type and age of the videorecorder, and are fully covered in the maker’s service manual. In general it will be necessary to check and replace as necessary drive belts and idlers which are showing signs of (or are prone to) slipping. In the case of idlers used for tape-loading or reel drive, removal, degreasing and a roughening of their drive surfaces with fine glasspaper is good precautionary practice. For sliding and bearing surfaces a drop of light machine oil is required, but several cautions must be observed: most drive motors must not be oiled – follow maker’s instructions; nylon and plastic bearing surfaces may need no lubrication, or a special type; and beware of contaminating friction surfaces (belts, idlers, pulleys) and particularly tape-contact surfaces (guides, heads, rollers) with lubricant. Where old grease, which may well have hardened, is being replaced, a light graphited grease is recommended.
Other aspects of routine deck maintenance or fault diagnosis are checks of reel-brake operation; confirmation of correct winding and take-up torques; checking and adjustment of back-tension; alignment of tape guides; adjustment of audio/control heads; and the position-setting of such things as spool turntables, loading-rings/ gears, and sensor- and mode-switches. The more important of these will be covered in the following sections.