User manual LG 28LB457B

[. . . ] Only for training and service purposes -2- LGE Internal Use Only SAFETY PRECAUTIONS IMPORTANT SAFETY NOTICE Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by in the Schematic Diagram and Exploded View. It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent Shock, Fire, or other Hazards. Do not modify the original design without permission of manufacturer. [. . . ]  end into a "U" shape the end of each of three leads remainB ing on the circuit board.  end into a "U" shape the replacement transistor leads.  onnect the replacement transistor leads to the corresponding C leads extending from the circuit board and crimp the "U" with long nose pliers to insure metal to metal contact then solder each connection. power Output , Transistor Device Removal/Replacement 1. Heat and remove all solder from around the transistor leads. Remove the heat sink mounting screw (if so equipped).  arefully remove the transistor from the heat sink of the circuit C board. nsert new transistor in the circuit board.  older each transistor lead, and clip off excess lead.  emove defective diode by clipping its leads as close as posR sible to diode body.  end the two remaining leads perpendicular y to the circuit B board.  bserving diode polarity, wrap each lead of the new diode O around the corresponding lead on the circuit board. nspect (on the circuit board copper side) the solder joints of I the two "original" leads. If they are not shiny, reheat them and if necessary, apply additional solder. fuse and Conventional Resistor Removal/Replacement 1.  lip each fuse or resistor lead at top of the circuit board hollow C stake.  ecurely crimp the leads of replacement component around S notch at stake top. S CAUTION: Maintain original spacing between the replaced component and adjacent components and the circuit board to prevent excessive component temperatures. 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 to separate from or "lift-off" the board. The following guidelines and procedures should be followed 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) After enter Service Mode by pushing "ADJ" key, 2)  nter "White Balance" by pushing "►" key at "9. White balance adjustment (Do not adjust white balance) (1) Equipment 1) Color Analyzer: CA-210 (LED Module : CH 14) 2)  dj. , RS-232C protocol is A needed) 3) Adjust Remote control RGB Gains are fixed data for each model. Insert RS-232C Jack which is connected with PC for White Balance or equivalent device. [. . . ]