Hafler 915 Service Manual

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NOTICE - IMPORTANT SAFETY INFORMATION RISK OF ELECTRIC SHOCK00 NOT OPEN WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE. The lightning flash with arrowhead symbol withinan equilateral triangle is intended to alert theuser to the presence of uninsulated dangerous voltage within the products enclosure, that may be of sufficient magnitude to constitute a risk of electric shock to persons. The exclamation point within an equilateral triangle is intended to alert the user of the presence of important operating and mainte- nance (servicing) instructions in the literatureaccompanying the appliance. 1. 2. 3. 4. 5. 6. 7. 8. 9. READ INSTRUCTIONS All the safety and operating instructions of your Hafler equipment shoul\ d be read before power is applied to the equipment. RETAIN OWNERS MANUAL These safety and operating instructions should be retained for future re\ ference. HEED WARNINGS All warnings on the equipment and in the operating instructions are impo\ rtant and should be followed. FOLLOW INSTRUCTIONS All operating and use instructions are important and should be followed.\ HEAT The equipment should be kept away from areas of high temperature, such a\ s heater vents, radiators, stoves/ovens, fireplaces, etc. VENTILATION The equipment should be used in an area suitable for proper ventilation.\ Care should be taken not to impede airflow in and around the cabinet. Do not mount on a carpeted shelf or in a sealed enclosure. Allow for pro\ per clearance above the equipment. WATER AND MOISTURE The equipment should not be used in or around water, such as a bathtub, \ sink, or swimming area. Also, the equipment should not be used in areas prone to flooding, such as a basement. POWER SOURCES The equipment should be connected only to a power source of the same vol\ tage and frequency as that listed on the rear panel above the power cord entry point. POWER CORD PROTECTION Power cords should be arranged so that they do not interfere with the mo\ vement of objects in the room: people, fan blades, utility carts, etc. Also, care should be taken that the cord is \ not pinched or cut, and placed so that it is not in danger of being pinched or cut, as in under a rug, around a tight corner\ , etc. 10. POWER CORD GROUNDING The power supply cord is of a three wire grounded type, designed to redu\ ce the risk of electric shock sustained from a live cabinet. It is assumed to be of suitable length for most uses of the equipment. T\ he use of extension cords and power strips is discouraged unless they are of suitable rating to delive\ r the required total current for safe operation of all connected equipment. Furthermore, extension cords or power strips must provide the same three\ wire grounded connection. It is important that the blades of the equipments plug be able to fu\ lly insert into the mating receptacle. Never remove the round grounding pin on the plug in an attempt to mate t\ o a two wire ungrounded receptacle: use a grounding adaptor with the grounding tab or wire suitably connected to earth ground. -l-

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11. NON-USE PERIODS During periods of extended non-use, the power cord should be unplugged f\ rom the power source. 12. CLEANING The equipment should be cleaned only as detailed in the operating instru\ ctions. 13. OBJECT AND LIQUID ENTRY Care should be taken so that objects and/or liquids, such as cleaning fl\ uids or beverages, are not spilled into the enclosure of the equipment. 14. DAMAGE REQUIRING SERVICE Hafler equipment should be serviced by qualified service personnel when:\ A. The power supply cord or plug has been damaged, or B. Objects have fallen, or liquid has been spilled into the equipment, or C. The equipment has been exposed to rain, or D. The equipment does not appear to operate normally or exhibits a marked c\ hange in performance, or E. The equipment has been dropped, or the enclosure has been damaged. 15. SERVICING The user should not attempt to service the equipment beyond that which i\ s described in the operating instructions. All other service should be referred to qualified service personnel. 16. CARTS AND STANDS The equipment should be used with carts or stands only of sufficient str\ ength and stability for the use intended. An equipment and cart combination should be moved with care. Quick stops\ and starts, excessive force, and uneven surfaces may cause the equipment and cart combination to topple. -2-

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INSTALLING CARTRIDGE LOADSCHANGING UNE VOLTAGE RATlNG Optional cartridge loading is a fine tuning matter. Many cartrid\ ges are not sensitive to loading and work well without it. Only a cartridges manufacturer can provide recommended loading, as every cartridge is different. And only the user can say for sure whether\ or not it produces meaningful sonic improvement. Components suitable for cartridge loads may be obtained from electronic \ parts or specialty audio component suppliers. should be 1% tolerance, metal-film, l/4 watt types. should be axial lead, 10% (or better) tolerance, miniature polypropyle\ ne or polystyrene types. As supplied from the factory, the 915 Preamplifier has been fitted with \ and pF capacitors installed in the appropriate sockets. While these values are\ suitable for most cartridges, the procedure described below may be used to alter these val\ ues. Review the installation instructions before attempting this procedure. If any doubt\ s exist about ones ability to install the cartridge loads, it is advisable that the procedure be co\ nducted by a qualified technician. WARNING! UNPLUG THE UNIT FROM AC POWER BEFORE ATTEMPTING THIS PROCE- DURE. FAILURE TO DO SO CAN RESULT IN SEVERE ELECTRICAL SHOCK AS WELL AS DAMAGE TO THE PREAMPLIFIER AND/OR PHONO BOARD. 1) Place the preamplifier on a soft, protective surface. Remove the four allen head screws (two on each side), and three phillips head screws, securing the bottom cover. Remove cover. 2) Refer to the diagram Installation Of Optional Cartridge Loads fo\ r the location of the appropriate sockets, and how to form the component leads. Make sure that the component leads are only long enough to securely mate to the sockets. Be sure not to stress the component lead where it enters the body of the part. Observe carefully w\ hich sockets are for MM (capacitors) and for MC (resistors). 3) Replace cover. NOTE: Even while experimenting with different optional loads, the cover must b\ e replaced before re-applying AC power, not only for safety reasons, but to shield hum and\ interference which can totally invalidate any attempts at sonic evaluation. CAUTION: When low value resistors are installed and selected by the MC switch pos\ ition, accidentally using this setup for a high output moving coil cartridge ca\ n result in deceptively normal output levels, but with improper cartridge frequency response. The 915 Preamplifier can be internally wired for two different AC line v\ oltage ranges: 100 - 120 VAC, or 200 - 240 VAC, 50/60 Hz. The configuration is labelled above the power cord connector. If the preamplifier will be used in a location that requires a different\ line voltage, it is possible to change the configuration. Review the modification instructions before at\ tempting this procedure. If any doubts exist about ones ability to change the line voltage, i\ t is advisable that the procedure be conducted by a qualified technician. NOTE: As supplied from the factory, units wired for 100-l 20 VAC have five Con\ venience Outlets, and the Power Switch controls the Switched Convenience Outlets only. (P\ ower is applied to the preamplifiers circuitry as soon as the unit is plugged in.) For units factory wired for 200-240 VAC, no Convenience Outlets are supplied, and the Power Switch controls appli\ cation of power to the preamplifiers circuitry. Note that changing the Line Voltage affects only the operating line volt\ age: the above described switching arrangements will remain the same. WARNING! UNPLUG THE UNIT FROM AC POWER BEFORE ATTEMPTING THIS PROCE- DURE. FAILURE TO DO SO CAN RESULT IN SEVERE ELECTRICAL SHOCK. -14-Resistors Capacitors 100 ohm resistors 220