Sony KV-32HS500 Training Manual page 15

DA-4 Overall Power Supply Block Description
Once 120V AC power is applied to the TV set (set plugged into the AC outlet), the Standby 5V power supply
(located on the A-board) is active and outputs regulated 5V (reference Figure 3-1). The STBY 5V is sent to the
M-board to partially power-up system control IC2300 and is also sent to the HA/HC board to power the Remote
Control Sensor (SIRCS).
The Main Converter power supply (DA-4) located on the D-board is fed AC (from A-Board) through the AC-
Relay (RY6501) and through Inrush-Current resistor (R6516). This limits the initial high current produced when
the TV set is first turned ON. The Inrush-Current resistor (R6516) is removed from the AC input path using
RY6501. Once the Main Converter power is up and running, the unreg11V output is fed back to RY6501, the
relay switch is closed and R6516 is bypassed in normal operation. The Main Converter power supply outputs the
following voltages:
•
+/- 15V
•
Unreg7V
•
Unreg5V
•
Unreg11V
•
36.5V
•
+135
•
+200
The High Voltage (HV) on the DA-4 chassis is developed using a switch-mode power supply identical to the one
found in the Main Converter power supply except for the use of the Flyback (FB) T8001 as the output transformer
(reference Figure 3-1). The HV power supply is located on the D-board. The HV power supply is activated
simultaneously with the Main Converter power supply. AC power is fed to the HV power supply from the AC-
RECT block (D6530), which also feeds the Main Converter power supply. The HV Converter output then drives
the FB transformer, which outputs the following voltages:
•
High Voltage (HV)
•
Focus Voltage (FV)
•
G2
•
ABL
The Heater Voltage is scan derived using H-Out (Q5030), T5001 and IC5006 also located on the D-board.
The Degauss Circuit (reference Figure 3-1) will be activated after IC2300 (M-board) receives an ON command
from either the ON/OFF button or the remote control, and after one of the following events have occurred:
•
The AC power was disconnected (indicating that the TV was possibly relocated).
•
The TV has been turned OFF for more then 15 minutes.
The base of Q501 receives a high from IC2300/pin 68 (turning Q501 ON). The ground path for the degauss relay
RY501 and the base circuit of Q502 are completed through the collector/emitter circuit of Q501. Q502 supplies
the initial kick voltage and current to RY501. Once C504 in the base circuit charges completely, Q502 will turn off
and a hold voltage is supplied through D501 (13V) from the STBY Power Supply circuit.
RY501 switch closes and sends AC through the degauss coil, eliminating any magnetic fields present in the
metallic parts in the picture tube, which could cause color purity problems. The degauss relay remains closed for
approximately six seconds and then opens.
3. Power Supply (DA-4 & DA-4X Chassis)
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