MARANTZ LC3050
Service Manual

SERVICING PRECAUTIONS
CAUTION! ! Before servicing receivers covered by this service manual, read and follow the SAFETY PRECAUTIONS on page 2 of this publication. General Servicing Precautions 1.Always unplug the receiver AC power cord from AC power source before; a. Removing or reinstalling any component, circuit board module or any other receiver assembly. b. Disconnecting or reconnecting any receiver electrical plug or other electrical connection. c. Connecting a test substitute in parallel with an electrolytic capacitor in the receiver. CAUTION! ! A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an explosion harzard. 2.Do not spray chemicals on or near this receiver or any of its assemblies. 3.Do not defect any plug/socket voltage interlocks with which receivers covered by this service manual might be equipped. 4.Always connect the test receiver ground lead to the receiver chassis ground before connecting the test receiver positive lead. Always remove the test receiver ground lead last. 5.Do not connect the test fixture ground strap to power supply heatsink in this receiver Electrost atically Sensitive(ES) Devices Some semiconductor(solid state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive(ES) Device.Examples Circuit Board Foil Repair Excessive heat applied to the copper foil of any printed circuit board will weaken the adhesive that bonds the foil to the circuit board causing the foil th separate from or �lift-off� the board. The following guidelines and procedures should be flollowed whenever this condition is encountered. At IC Connections To repair a defective copper pattern at IC connections use the following procedure to install a jumper wire on the copper pattern side of the circuit board.(Use this technique only on IC connections.) 1.Carefully remove the damaged copper pattern with a sharp knife.(Remove only as much copper as absolutely necessary.) 2.Carefully scratch away the solder resist and acrylic coating(if used) from the end of the remaining coopper pattern. 3.Bend a small �U� in one end of a small guage jumper wire and carefully crimp it around the IC pin. 4.Route the jumper wire along the path of the out-away copper pattern and let it overlap the previously scraped end of the good copper pattern. Solder the overlapped area and clip off any excess jumper wire.

SERVICE MANUAL

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