LG 50PK950 Training Manual page 50

Turn On Sequence Text
Turn On Sequence Text
STBY 5V (Stepped down to 3.3V_ST by IC400) powers on the Microprocessor IC701 on the Main board. This also starts
the 10Mhz Oscillator (X700) however, the Microprocessor is not functional until after it is Reset. The Reset circuit (IC701)
is energized when 3.3V_ST arrives.
AC Det is 0V when the set is in Stand-By, but rises to 4.07V when the set turns on by the Relay-On Command. AC Det is
routed to the Microprocessor. If AC Det is missing, the TV will not turn on. The Relays will engage, but after that, no
other functions.
At power on the 1 st output from the Microprocessor is, the Relay On command called (RL-ON) which turns on
the following SMPS supplies: +5V for Video Processing 17V for Audio Amplification and Tuner B+.
On the Main board, 17V is stepped down to 7V (IC404) then 5V (5V_TU by IC405). The 17V is also sent to the Audio Amp
(IC300). The SMPS (+5V) creates a signal called (ERROR DET) and is sent to the Main Board. ERROR DET is Not used by
the Main board.
The 2nd output from the Microprocessor is the (M_ON) command which turns on (3) supplies:
(1) M5V (Monitor 5V): For the Control Board, Y-SUS Board and Z-SUS Board. (The M5V is routed through the Y-SUS
to the Control Board then to the Z-SUS).
(2) Va: (Voltage for Address) For amplification voltage for the TCPs driving the vertical electrodes. (Voltage routed
through the Y-SUS then to the X-Drive boards.
(3) Vs: Voltage for Sustain sent to the Y-SUS and to the Z-SUS) used for amplification voltage driving the horizontal
electrodes.
On the Y-SUS, when M5V arrives, it develops 3 voltages: FG15V, FG5V (FG=Floating Ground) and 18V.
The 18V is routed through the Control board to the Z-SUS. The FG5V is routed to the Y-Drive boards for the low voltage
processing voltage. When Vs arrives on the Y-SUS, it develops 2 additional voltages; -Vy and VSC which are adjustable.
When the M5V from the SMPS through the Y-SUS arrives on the Control board, the control develops 3.3V and 1.8V for
internal use and 3.3V which is routed down to the each X-Board for each TCP's low voltage processing voltage.
The text below is related to the previous page.
50 October 2010 50PK950 Plasma