Technology of Q 2500 colour TV set
Technology of Q 2500 colour TV set
Technology of Q 2500 colour TV set
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<strong>Technology</strong> <strong>of</strong> Q <strong>2500</strong> <strong>colour</strong> <strong>TV</strong> <strong>set</strong>Q<strong>2500</strong> Operating ControlT8101Standby transformer3 5MP04W8613VH-JSTws 7R92 3pol3from BB21R8134D8133DF08SF8133B8103R10C81334u7/400VT630mAMP031C813647nI8131VIPER1228734MP0265MP01R81380RD8131LL4148C813210u41D8138LL41482 8C8106470uI8122TLP621(BL)-D44132D8121BYG20DR8121470RI8123TL431ACLPR81221kC8123100nR81231k2R81241k5R812612kC8107100nL8106FE_PEC8103100nC8104100uU5SBU5SBW8181JST sw s8W86112pol sw 7R92to BB21642Overtravel contactL810121D8106LL4148Standby-LEDOvertravelON/OFF7654Mains21W81032pol ge 7R92531S8101C8118100nQ8114BC847BWR8113Q8111BC847BW2k2R811122kR811222kD8114R82041kLL4148R82191kR82020RD8202C12VD8201C12V321D8207redgreenD8207D8204C12VThe rectified secondary voltage is applied topin 2 <strong>of</strong> the relay winding L 8101. via protectiveresistor R 106. The cold end is open sinceQ114 is non-conducting and the receiver is instandby mode. This is indicated by illumination<strong>of</strong> the red LED.Transistor Q 8114 is blocked, if the workingcontact is open, the device is in standby,which is indicated by illumination <strong>of</strong> the redLED.If the processor receives an ON commandfrom the infrared detector it <strong>set</strong>s its appropriateswitch output to low level. This is then fedto the base <strong>of</strong> Q 8111 via pin 5 in plug W 8181which is blocked. Via R 813, U5 SB makestransistor Q 8114 switch. The cold end <strong>of</strong> therelay coil is earthed, the working contact isclosed and the main voltage flows to the mainpower supply circuit via pin 1 <strong>of</strong> W 8613,thereby switching the receiver on.2.2 Blocking oscillator type powersupplyThe voltage supply in the Q 2400 chassis isdrawn once again from a free-running blockingoscillator type power supply. TDA 4605 isused as the control and regulating circuit. Interms <strong>of</strong> its function, this IC resembles thewell-known TDA 4601.It has, however, a different type <strong>of</strong> outputstage. The 4605 is designed to control a fieldeffect transistor.This circuit uses a BUZ 91 MOS-FET as theswitching transistor. Since control <strong>of</strong> field effecttransistors requires virtually no current,reducing the need for heat dissipation, it hasbeen possible to eliminate the heat sink in theTDA 4605 control IC and house the circuit in adual-in-line package.Dokument Q <strong>2500</strong> 13 © Loewe ProCollege
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