LG / GOLDSTAR FB915B free download

File name monitor_©_.pdf

BLOCK DIAGRAM DESCRIPTION OF BLOCK DIAGRAM 1. Line Filter & Associated Circuit This is used for suppressing noise of power input line flowing into the monitor and/or some noise generated in this monitor flowing out through the power input line. That is to say, this circuit prevents interference between the monitor and other electric appliances. 2. Degauss Circuit & Coil The Degauss circuit consists of the degaussing coil, the PTC (Positive Temperature Coefficient) thermistor (TH901), and the relay(RL901). This circuit eliminates abnormal color of the screen automatically by degaussing the slot mask in the CRT when turn on the power switch. When you need to degauss while using the monitor select DEGAUSS in the SPECIAL on the OSD menu. 3. SMPS(Switching Mode Power Supply). This circuit works with power of 90~132Vac/196~264 Vac (50/60Hz). The operation procedure is as follows: 1) AC input voltage is rectified and smoothed by the bridge diode (D901) and capacitors (C912,913). 2) The rectified voltage (DC voltage) is applied to the primary coil of the transformer (T901,T902). 3) The control IC (IC905) generates switching pulse to turn on and off the primary coil of the transformer (T902) repeatedly. 4) Depending on the turn ratio of the transformer, the secondary voltages appear at the secondary coil of the transformer (T902). 5) These secondary voltages are rectified by each diode (D922,923,924,925,931) and operate the other circuits. (Deflection , Video Amplifier ,... etc.) The switching IC (IC901) controls input-pulse-width and generates secondary voltages by sub-transformer (T901). 4. Display Power Management Circuit. This circuit control power consumption of the monitor by detecting H and V sync signal. There are Stand-by and suspend mode. When no horizontal or vertical sync signal input, the circuit consists of Q903 and IC913 becomes stand-by and suspend mode. Its power consumption is below 8W. 5. X-ray Protection. This circuit detects the rectified DC voltage comes from the FBT pin 6. If the high volltage of the FBT reaches up to about 30kV (abnormal state), high voltage control PWM IC (IC2061) detects it. And PWM IC (IC2061) prevent output voltage to the gate of switching FET(Q507).It stops operating primary circuit of the FBT (T703), and high voltage is not be generated.(In the normal state, the high voltage is about 27kV.) 6. Micom (Microprocessor) Circuit. The operating procedure of Micom (Microprocessor) and its associated circuit is as follows: 1) H and V Sync signal is supplied from the D-sub to the Micom (IC271). 2) The Micom (IC271) distinguishes polarity and frequency of H and V sync. 3) The Micom controls each OSD function signals.(Hsize, H-position, V-size, etc.) 4) The controlled data of each mode is stored in itself. User can adjust screen condition by each OSD function. The data of the adjust screen condition is stored automatically. 7. Horizontal and Vertical Synchronous Processor This circuit generates the horizontal drive p