STA-235 (310-2065) Care and Maintenance Faxback Doc. # 16066 TAPE RECORDER CARE A clean, demagnetized recorder will give its best performance for many years, while a dirty recorder can mangle or ruin pre-recorded tapes in a very short time. An inexpensive demagnetizer (degausser) removes residual magnetism from the tape heads. This will insure the lowest possible hiss and distortion and the best possible high frequency response. Always clean and demagnetize the recorder before making critical recordings. Under normal conditions you should demagnetize the recorder after every 10-15 hours of play. With normal use you should clean the heads and metal tape guides once or twice a month with a special solvent such as Realistic Recorder Cleaner (catalog number 44-1010). Moisten a clean cotton swab with the fluid and rub the heads with short circular movements. Then, clean oxide deposits from all metal tape guides. There are also a number of cloth cleaning tapes which can be played like a tape for fast, easy cleaning. You can even use the demagnetizer to help remove oxide particles trapped deep in the head gaps. Place a cleaner-moistened cotton swab over the gap and bring the demagnetizer into contact with it. Move the swab and demagnetizer in short, circular sweeps. Gradually withdraw the demagnetizer and remove the dirty swab. Yearly preventative maintenance by an authorized technician reduces the possibility of expensive major breakdown and keeps the recorder in peak operating condition. RECORD & PHONO CARE Even a small record library is a large investment, which, with proper care, can give years of full-fidelity musical enjoyment. Generally speaking the best way to reduce record wear is to decrease the stylus force - but only if the cartridge and tonearm are designed for light tracking. If the force is less than the cartridge or tonearm is designed for, the needle will bounce around in the groove. This causes breakup, distortion, skipping and excessive wear. Always track your cartridge within the range suggested by the manufacturer. If you play mostly rock or classical records (typically recorded at high volume) you should use one the heavier suggested tracking forces. Records often carry dust-attracting static charges and should be cleaned before use. Playing a dirty record grinds dust against the record walls until it wears away the high frequencies and increases background noise. The most effective cleaners use an ionizing formula to remove the static charge and a cut velvet pad to lift particles from the groove. Occasionally you will need to remove dust and dirt from the needle. For best results trim the bristles of a #2 or smaller camel's hair brush and then dip in rubbing alcohol and touch the needle lightly. Brush forward very gently to remove the dust. CAUTION: Brushing from front-to-back or side-to-side may cause permanent damage. To reduce record wear and maintain top performance, you should examine the stylus carefully every 6 months. You can take it to the nearest Radio Shack store for a free checkup. While you're there, look over the wide selection of record care accessories. CARING FOR THE RECEIVER The STA-235 is built for a lifetime of precision musical reproduction. The receiver's wood case should be polished periodically with lemon oil. NOTE: Wax produces a glossier finish but may eventually cause a dull wax buildup.) If the front panel requires cleaning use a soft, damp cloth (DO NOT use solvents). Speaker Protection Relay Circuit You may have noticed some stereo systems which produce a loud "pop" in the speakers when power is turned "on". This "pop" noise has been known to blow speakers - especially with high-power amplifiers such as the STA-235. But don't worry - it won't happen with this Receiver. We've built in a special relay-protection circuit to prevent such damage. The high-power output stages are kept off for a couple of seconds after power is turned on, till the power supply circuit and audio preamp stages have had a chance to stabilize - then the relay circuit switches in power to the audio output stages. Of course, this means you don't hear sound for a couple of seconds after power is first turned on - but you won't mind that, now that you know the speakers are protected! Overload Protection We've got another important protection circuit - which protects the Receiver from overload. If too much current flows in the output circuit (from excessively low impedance [combinations less than 4 ohms], shorted speaker terminals, etc.) a protection circuit activates immediately and the output connections and the speaker impedance (don't use 4 ohm speakers if you use more than one pair). Thermal Protection The Receiver has built-in thermal overload protection. That means that it can not become abnormally hot and damage some portion of the circuitry. If internal temperatures do rise abnormally, the Receiver will automatically silence itself. If this happens, check to be sure you have not placed something over the ventilation holes - if you have, remove it. If you are using speakers with excessively low impedance, the amplifier circuit may be over-driven and thus producing excessive heat. This can be caused by using 4 ohm speakers on main and remote - if you use remote with main speakers, be sure to use either 8 or 16 ohm speakers. In any case, if the Receiver does turn itself off, set POWER to off, check ventilation and then check to be sure the speakers are properly connected and that you are not using a combination of 4 ohm speakers for both main and remote. The protective circuit is triggered by temperature, thus it may take a few minutes for the circuitry to cool down and allow the unit to come back on. If everything is OK, turn power back on. If the Receiver does not come back on, you may have to wait a few more minutes for everything to cool adequately - it should never take more than about 20-30 minutes for this cool down cycle, or, check the fuse (4A) on the rear panel. Replace only with the same size and rating. (llg/all-07/21/95)