Hitachi 61HDX98B Manual page 5

BLOCK DIAGRAM EXPLANATION POWER SUPPLY BLOCK
The 61HDX98B utilizes two switching power sup-
plies.
DP-85's stand by switching mode operation is different
from AP-7X and 8X chassis's. Switching frequency of
AP-7X and 8X chassis is dropped to 20kHz during
stand by mode. But the DP-85's power supply is not
dropped during stand by mode. DP-85's is operated
about 100kHz.
Normally Power Supply switching is operated as fol-
lowing.
T901: 25- 56 kHz (Normal)
100-200 kHz (Stand by)
TP91 30- 53 kHz (normal)
POWER SUPPLY UTILIZED FOR THE DIGI-
TAL AND SIGNAL CIRCUITS:
(Sub Power Supply PWB)
This supplies power primarily to the Digital circuits, i.
e. DM-1 module. This supply runs anytime the set is
plugged into an AC outlet.
The voltages produced are;
•
+33V,
•
Power for the Satellite dish which is switched be-
tween 13V and 19V dependant upon the channel
being received.
•
Stand By 12V also called A12V
•
TV9V
•
TV5V
•
3.3V
•
-5V
POWER SUPPLY UTILIZED FOR THE DE-
FLECTION, AUDIO and DIGITAL CONVER-
GENCE CIRCUITS: (Deflection PWB)
This supply only operates when the set is turned ON.
When the ON command is received from the DM-1
module, relay S-901 energizes and delivers AC to the
main bridge rectifier D903 located on the Sub Power
Supply PWB.
This supplies power primarily to the Deflection circuit
for the collector of the High Voltage generation circuit
and the collector of the Deflection Output transistor.
Also, the Convergence output amps and the Audio
output amps derive their voltages from here as well.
The voltages produced are;
•
+130V used for Deflection and High Voltage cir-
cuits.
•
220V used for the collectors of the R, G, B drivers
on the CRT PWB and the Velocity Modulation
circuits.
•
6.3V to drive the CRT Heaters.
•
+28V for the Convergence, Velocity modulation
and Audio Out circuit.
•
+13V for Vertical.
•
-13V for Vertical and also converted down to
the –5V for the Digital Convergence Unit.
The TV9V supply generated from the Power Supply
for Digital listed above, is regulated down to +5V for
the Digital Convergence Unit and the A12V for the
Power Supply for Digital is used as a switched On/Off
for the Deflection Vcc by the Rainforest IC.
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