Power Supplies - Sony KD-34XBR2 Training Manual

Power Supplies

Chart 18-1 shows that there are four power supplies found in the RA-5A projection TV chassis. Each power
supply starts one at a time dependent upon prior stage operations for safety.
Name
Standby AC input
Primary AC relay (RY6001) & surge relay
(RY6002) closes
Secondary 1) Primary PS outputs VC1 (HIGH at
D6049)
2) Main Micro outputs Main Sw HIGH
(CD6101/9)
3) Surge relay RY6002 must energize.
HV 1) 135Vdc (CN8013/9, D board)
Converter
2) 12Vdc (CN8016/1, D board)
(not shown)
3) H Drive (CN8006/10, D board).
Standby PS
This is a simple 60Hz step-down transformer power supply with a 5V regulator IC6106 at the secondary. The only
unique part in this supply is the TH6001 thermistor in series with the primary winding. Since T6003 is working 24
hours a day, TH6003 prevents T6003 damage if the line voltage goes high for a prolonged time as commonly
occurs during summer. If the abnormally high AC input voltage causes T6003 to draw more current, TH6001 will
increase resistance to offset the current draw, preventing the transformer from over-dissipating. TH6001 mea-
sures 24 ohms cold and R6057 = 4.7 ohms.
The standby 5 volts can be easily checked at the G board' s CN6101/pin 1. See Figure 18-2 for the G board
connector locations. Pin 1 of each connector is at the right.
Primary PS
The primary power supply starts as soon as the Main Micro IC001 B board turns on the AC relay RY6001. Only
three voltages are output and are sent to the A board. From the A board, various voltages are sent to the QM, B
and AD boards (final destinations). Chart 18-2 shows these destinations:
Chart 18-1 – RA-5A Power Supplies
Startup Requirements
CN6102
CN6104
G Bd.
AC In
Figure 18-2 - G Board Connectors
18. RA-5A Chassis - Power Supply Block
Standby +5Vdc for Micro IC001 on B board
?? Powers the Q Box and circuits on the A board.
?? VC1 Starts the Secondary PS.
?? 135V for H Deflection, HV, Tuner (A & D Bd);
?? 22V for Convergence IC Amps (D bd
?? 15V for V Deflection and Op amps (D bd)
?? 19V for Audio Output (K Bd)
Develops, regulates and checks the High Voltage to
the three picture tubes.
CN6101
Prim
R6099
Second
R6041
78
Purpose
CN6106