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18. RA-5A Chassis - Power Supply Block
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.
Chart 18-1 – RA-5A Power Supplies
Name
Startup Requirements
Purpose
Standby
AC input
S5Vdc for Micro IC001 on B board
Primary
AC relay (RY6001) & surge relay
(RY6002) closes
??
Powers the Q Box and circuits on the A board.
??
VC1 Starts the Secondary PS.
Secondary
1) Primary PS outputs VC1 (HIGH at
D6049)
2) Main Micro outputs Main Sw HIGH
(CD6101/9)
3) Surge relay RY6002 must energize.
??
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)
HV
Converter
(not shown)
1) 135Vdc (CN8013/9, D board)
2) 12Vdc (CN8016/1, D board)
3) H Drive (CN8006/10, D board).
Develops, regulates and checks the High Voltage to
the three picture tubes.
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.
CN6102
CN6101
CN6106
Prim
R6099
Second
R6041
CN6104
AC In
G Bd.
Figure 18-2 - G Board Connectors
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:
Содержание KD-34XBR2 - 34" Hdtv Fd Trinitron Wega
Страница 77: ...74 RA 5A Chassis Board Layout ...
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