User manual GRUNDIG CUC 7303 F SERVICE MANUAL

[. . . ] The regulations and safety instructions shall be valid as provided by the "Safety" Service Manual, part number 72010 800 0000, as well as the respective national deviations. You can order these test equipments from the Service organization or at the address mentioned below. We refer to you that these test equipments are already obtainable on the market. This identification gives information on the technical/mechanical state of production. [. . . ] The only way to check the data and clock leads when servicing is by measuring the TTL-levels (L 0. Service note: The I2C-bus data is also present without a command from the IR remote control handset. To localize the fault, the modules and components connected to the data bus must be unsoldered or unplugged one after the other. With the start command, the processor feeds out a "High" level at Pin 40 and the voltage UStandby starts the TV via CT826, IC676-(1) by means of the voltages +B, 12V (see Power Supply). After switching on, the processor (IC850) transfers the operating data from the internal memory via the I2C-bus to the bus-controlled modules and circuits. By evaluating the different voltage levels, the processor IC850-(27), -(28) knows which button on the keyboard has been pressed. The character generator feeds out the display data via the output ports 47, 48, 49 of the microprocessor at an amplitude of 4. 7 Protection Circuit USchutz The base of the transistor T511 is connected via R511 to the low-end point of the vertical output stage, and via R512, D512, D513 to the reference pulse F from the horizontal output stage. 6V and higher switches the transistor on; via its collector the transistor switches IC850-(32) to ground. If the voltage +D fails there is no direct voltage present at the output of the vertical output stage IC400-(5) and consequently the proctection circuit input IC850-(32) is pulled to ground. at the same time the collector (SB lead) is connected via R513 , D514 , and CD516 to the low-end point of the high-tension winding. When the Zener voltage is exceeded due to too high a beam current the collector voltage decreases to 0V so that the TV switches to standby. 1 Overview: With this TV design the whole signal processing is carried out in a single IC, i. 4 External CCVS Signal At the signal source switch IC150-(15) either an external CCVS signal from the Scart socket or the RF-CCVS signal is present. The voltage UVQ at IC150-(16) decides which signal shall be passed on, the CCVS signal from the Scart socket or else the RF-CCVS signal. However the CCVS signal from the tuner can be measured at output Pin 19 of the Scart socket. In one path, the demodulated and uncontrolled AF signal is fed out at IC150-(1), it is then amplified by the transistors CT917, CT916 and passed on to the Scart socket. In another path, the demodulated and controlled AF signal is present at IC150-(50) and is fed to the AF-IC TDA7233. the luminance signal passes through the colour trap integrated in the IC. The delay line provided in the IC is used to correct delay time differences between the luminance and chrominance signal. The colour transient improvement (peaking) which follows is also realized in this IC. From this chroma signal, the burst is separated which is used to synchronise the colour oscillator in phase and frequency. [. . . ] From this line oscillator the "vertical oscillator" is derived by counting the number of lines. After having counted 312 lines, the counter feeds out a field sync signal so that the horizontal and also the vertical deflection is achieved without using an external synchronising signal. On reception of a synchronising signal, the line oscillator will first be synchronised. In this case too, the line counter supplies a field deflection signal. [. . . ]