Video amplifier circuit: TDA6103

TDA6103 contains three sets of video output amplifiers with a video bandwidth of 7.5MHZ. It has built-in overheating protection and anti-CRT flashover protection. The picture shows the application of TDA6103 on Changhong D2191 model.

Pins (1), (2), and (3) of TDA6103 are R, G, and B input pins, and pins (7), (8), and (9) are R, G, and B output pins. RP1504 and RP1506 are dark balance adjustment potentiometers, and RP1513, RP1514 and RP1515 are bright balance adjustment potentiometers.

V1501 and peripheral components form a shutdown dimming circuit. During normal operation, 8V voltage is added to the B pole of V1501 through R1526, and at the same time, it is added to the E pole of V1501 through V1502. Due to the existence of V1502, the B pole voltage of V1501 is about 0.6V higher than the E pole voltage at this time, and V1501 is cut off. V1501 has no effect on the audio amplifier circuit. At the same time, C1507 is charged with a voltage of nearly 8V.
When the power is turned off, the 8V voltage disappears. However, since the voltage on C1507 cannot mutate, V1501 is turned on due to forward bias, and the voltage on C1507 The C pole of V1501 and V1503-V1505 are added to the (1), (2) and (3) pins of TDA6103, causing the internal three-view amplifier tube to saturate and conduct, and the voltage of (7), (8) and (9) pins drops rapidly. , the picture tube bundle current increases, and the accumulated charge on the high-voltage capacitor of the picture tube is quickly discharged, achieving the purpose of shutting down and eliminating the bright spots.