Votos - 2, Puntuación media: 4.5 ( )

Fabricar: Hitachi Tamaño del archivo: 3.06 mb Nombre del archivo: Idioma del manual:

All other service alignment data is stored on the PCB-E2P located on the DM assembly. When replacing the DM assembly, retaining the original PCB-E2P will minimize the need for any realignment. 2-6 3-1 Chapter 3 Power Supply From the above diagram, it is apparent that the V23 Chassis has four Power Supply Operational Modes. 1) Low Energy Mode 2) Standard Standby Supply Mode. 3) Time Shift Recording Mode. 4) Conventional PTV On Mode. Low Energy Mode When the Low Energy Mode is activated the TV uses less than 3 Watts while the set is Off. The Low Power Standby Supply generates a 9VS supply. Three additional supplies are derived from the 9VS supply, 5VS, 3.3V-ES and 3.3VS-1. These supplies furnish power for the PTV Control Circuitry. This is the only circuitry active in the Low Energy Mode when the PTV is Off. In the Low Energy Mode the set is booted up each time the TV is switched On. When switched On, the LED will flash for approximately one minute before the TV powers On. Low Energy Mode Activation The Low Energy Mode is activated from the user's Onscreen Menus. To activate the Low Energy Mode: 1) Press "MENU". 2) Select the Setup Menu (Shown in Figure 3-1). 3) Use the Remote Direction Keys to activate, or deactivate the Low Energy Mode. Low Energy Standby Regulator Figure 3-2 illustrates the Low Energy Mode Regulator Circuitry. IC9A10 is the same is the same type of regulator used in the V20. 3-2 A 132 kHz internal Oscillator drives an internal Output FET. The signal from the FET at pin 5 of IC9A10, drives transformer T9A10. Signal from pin 10 of T9A10 is rectified, generating the 9VS supply. The signal from pin 2 of the transformer is rectified and takes two paths: 1) To pin 1 of IC9A10, adding to an internally generated 6.3V supply. 2) Through R9A18 to the Standard Standby Regulator circuit, serving as a start-up voltage source. For regulation a sample of the 9VS supply is fed back to pin 4 of IC9A10, via D9A14 and PC9A20. Regulation IC9A10 does not regulate by controlling the PWM of the oscillator signal. Under normal load, some of the 132 kHz cycles are removed and not applied to the FET. Under light loads, more of the cycles are removed, and during heavy loads few, if any cycles are removed. This is illustrated in Figure 3-3. Figure 3-1: User Setup Menu 3-3 Low Energy Power Distribution Figure 3-4 shows the Low Energy Mode Power Distribution. As stated earlier, the Low Energy 9VS is the source for the 5VS, 3.3V-ES and 3.3VS-1. The 5VS and 3.3VS-1 supplies power to the IC7A00 the PTV Control .PC. The 3.3V-ES supplies power to the PTV Control circuit E2PROM, now located on the PCB-TERMINAL. The 9VS supply also provides power for the Antenna Relay in the RF Switch. 3-4 Standard Standby Supply The Standard Standby Regulator circuit is shown in Figure 3-5. Start-up The Start-up Voltage Supply is from R9A18 in the Low Energy Mode circuit, refer to Figure 3-2. The SUBPOWER command from the Control Circuitry activates the Standby Supply. When SUB-POWER goes High: • Q9A09 conducts, activating a Photo Coupler in PC9A20. • The Photo Coupler turns Q9A12 On, supplying start-up voltage to pin 4 of IC9A20. • When oscillation starts, the signal from pin 2 of T9A20 is rectified by D9A22 and added to the start-up voltage to maintain oscillation. Regulation The secondary 12VS supply is monitored for regulation. A sample of the 12VS is compared to a reference in IC9A21. A correction voltage from IC9A21 controls a second Optical Coupler in PC9A20. The output of the Optical Coupler is applied to pin 5 of IC9A20, controlling the PWM of the oscillator's signal. 3-5 Standard Standby Supplies Two Standby supplies are generated directly from T9A20, 12VS and 6VS. Both of these supplies are directed to the DM module, and are denoted as 12VDM and 6V-DM. A 30VS supply is derived from the 12VS source using voltage doubler circuitry, comprised of D9A31, D9A32, C9A32 and C9A27. The resulting 30VS is the source for a 28V-DM supply. Standby Power Distribution Figure 3-6 illustrates the Standby Power Distribution. As mentioned earlier, the 12VS is source for 12VDM, and through the Voltage Doubler circuitry is the source for 30VS and 28-DM supplies. The 12VS is also directed to Horizontal Drive Circuitry and is the Start-up voltage source for the Switched Supply Regulator. In addition to being the 6V-DM source, the 6VS supply supplies power for CRT Protect circuitry, and is the source for the 3.3V-1 and 5V-2 supplies. Time Shift Recording Power Supplies. The Time Shift Record Supplies are switched supplies derived from the Standby 12VS supply. They are activated during Time Shift Recording and when the PTV is switched On. The Time Shift Power Supply circuit is shown if Figure 3-7. The supply is activated by the PON-1 command from the Control Circuitry. When Off, the PON-1 line is low, holding Q921 On, which holds Q9A20 Off by pulling its Gate low. 3-6 When PON-1 goes High, Q9A21 turns Off, allowing Q9A20 to turn On. With Q9A20 conducting, ...

Descargar ahora

Introduzca dos números de la imagen: