Question about Samsung HC-P4752W 47" Rear Projection HDTV-Ready Television
Hello i have a samsung projection tv 42 inch until recently it was working fine.The problem now is the colour is distorted and it is like there are 2 pictures in differnt colours overlapping each other ,can this problem be fixed if so can you HELP please. Thanks
This problem happens to many sets of all different manufacturers and models of c.r.t proj. type tv's. What has happened to your tv is most likely that one of the 2 ic's (large black modular looking things about 2" by 1" by 3/8" fastened to a large aluminum slab of metal called a heat sink) on one of the large circuit boards has SHORTED OUT. The number on these ic's is stk392-***. If the asterisks shown are 110 then there is an upgrade of 180. If say the last 3 numbers are 040 then there is no upgrade. Anyway both Ic's need to be replaced and any associated resistors in the circuit area that have burned open or got hot and changed value also must be replaced..in addition a calibration of the convergence may need to be done either according to your operators manual or factory service manual by using your remote control and/or buttons on the front panel of the tv. Sometimes a samsung will have a small circuit board separate from all neighboring circuit boards that only has the convergence circuit on it. In that case the complete board should be replaced if possible. Do not attempt to do this repair yourself unless you are expert in electronics or guided by one. Above all do not attempt to make any repairs without being sure that the set is NOT plugged in. Invariably the heat sink compound (white pasty looking material sandwiched in between the ic metal backing and the heat sink) has dried out or was not ample enough and/or the screws fastening the ic's were not tight enough to secure properly the ic's mentioned. This heat sink compound material is PARAMOUNT to allow proper heat transfer and needs also to be replaced with known excellent silicon heat sink compound that exhibits excellent heat transfer properties and will not dry out. Careful soldering and de-soldering measures must be taken as well to insure a no-damage repair procedure as well as being careful to create no solder bridges between the pins of the ic's when the new ones are inserted. Be very careful of static charge when handling all delicate electronics boards and their parts. Before beginning also make sure there are no large charged capacitors that have not been discharged using a 1k ohm resistor and a piece of wire usually an alligator type test lead. This entire procedure usually takes up to 3 hours if done properly. In addition before new compound is applied the old compound must be thoroughly removed with anhydrous alcohol(99% isopropyl ). Finally because of this problem it is highly recommended that cool airflow around the back of the tv is insured. Good Luck
Posted on Aug 23, 2007
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