In the narration below, we will introduce the breakdown example that encounters in overhauling a process actually, in these breakdown, some has certain difficulty, some has catholicity, the hope can maintain working reference as the reader. Because of movement the circuit of all sorts of model televisions pursues basic and identical, which kind of model are not referred in particular to in the following introduction so, circuit graph can consult TC2125C, the test data that mentions in article, it is marine MF10B ammeter measures above those who get. Exemple 1. Screen shows without grating, but character shows be in normally most when beginning to overhaul this breakdown, because be opposite,the working principle of A3 movement still is not to understand very much, took not little roundabout way so. The output that what think above all is luminance signal cites a base, namely N101(24) foot. Measure this foot voltage to be 7V, very more than normal 4.5V tower above, but examination periphery component is normal, try even change N101 also of no help. Combine actual condition analysis, image brightness is taller, (The voltage of 24) foot is lower, and brightness control is in N101 (35)(36) foot, measure discovery this 2 periphery that cite a base all normal, measure (the contrast control of 12) foot is normal also, maintain temporarily get into trouble. Discover in the experiment after, this breakdown appears below condition of S-1, S-2 only, and it is normal that the TV set issues in S-3, from this consideration, the problem ought to appear on circuit of appropriative of S-1, S-2, and special circuit basically makes type centrally on changeover board, try era to change the whole transition that make type board: A3 board trouble removal. The changeover making type below trade board the component one by one that go up is measured, discover diode VD06 to basically already did not guide, change a normal switch diode, the changeover that make type board change former position, breakdown is eliminated thoroughly namely. Because of VD06 to basically do not guide those who cause is signal of the video below type is made cannot enter brightness to handle circuit and travel field synchronism in PAL detached circuit, pass the overhaul so this breakdown, make we realize the impact between this kind of breakdown of this machine and video signal, pass farther test, the parent that tells this breakdown truly depends on N101(33) foot, namely the input of synchronous depart cites a base. In the following overhaul, encounter S-1, S-2 for many times grating is not had below condition, have character but the regular breakdown below S-3 condition, great majority and diode VD06 guide knows character undesirable about.

[1] [2] [3] [4] [5] [6] [7] issues one page