Power Supply Basic Operation - LG 50PV450 Manual

Power Supply Basic Operation

Power Supply Basic Operation
AC Voltage is supplied to the SMPS Board at Connector SC101 from the AC Input assembly, routed to the two Bridge
Rectifiers D101 and D102 which then route the primary voltage to the PFC circuit (Power Factor Controller). Standby 5V is
developed from 160.1V source supply (which during run measures 390V measured from the primary fuses F801 and F302).
This supply is also used to generate all other voltages on the SMPS. This supply is also used to generate all other voltages on the SMPS
The STBY5V (standby) is B+ for the Controller chip on the back of the SMPS board (IC701) and output at P813 pins 13 and
14 then sent to the Main board for Microprocessor (IC600) operation (STBY 3.47V RUN 5.14V).
When the Microprocessor (IC1 on the Main Board) receives a "POWER ON" Command from either the Power button or
the Remote IR Signal, it outputs a high (2.4V) called RL_ON at Pin 15 of P301 to P813 on the SMPS. This command g
causes the Relay Circuit to close Relay RL103 bringing the PFC circuit up to full power by increasing the 160V standby to
390V run which can be read measuring voltage at Fuse F302 and F801 (390V) from "Hot" Ground. AC Detection (AC Det) is
generated on the SMPS, by rectifying a small sample of the A/C Line and routed to the Controller (IC701) where it outputs
at P813 pin 16 (4.4V) called AC_DET. and sent to P301 to the Main Board. If missing, the TV will attempt to turn on, but will
shut right back off.
Wh When RL_ON arrives, the run voltage +5V source becomes active and is sent to the Main Board via P813 (+5.1V at RL ON
pin 5, 6 and 7). The (Error Det) from the SMPS Board to the Main Board can be measured at pin 8 of P813 (2.87V STBY
and 4.9V RUN), but it is not used. The RL-ON command also turns on the 17V (Audio B+) which is also sent to the Main
Board. The 17V (17V) Audio supply outputs to the Main board at P813 pins 1 and 2 and used for Audio processing.
The next step is for the Microprocessor on the Main Board to output a high (3.2V) on M ON Line to the SMPS at P813 Pin p
17 which is sensed by the Controller IC701, turning on the M5V line and outputs at P811 pin 7 to the
Y-SUS board.
The Controller (IC701) also uses the M_ON line to turn on the VA and the VS supplies. (Note there is no VS On Command
in this set). VS is output at P811 to the Y-SUS board P210.
(VA pins 6 and VS pins 1 and 2). Note: The Va is fused (FS203) on the Y-SUS then routed out P203 pins 4-5 to the X-Board (VA pins 6 and VS pins 1 and 2) Note: The Va is fused (FS203) on the Y SUS then routed out P203 pins 4 5 to the X Board
Left. Vs is routed out of the Y-SUS P218 pins 4-5 to P203 on the Z-SUS where it is fused by FS201.
AUTO GND Pin 18 of P813: This pin is grounded on the Main board. When it is grounded, the Controller (IC701) works in
the normal mode, meaning it turns on the power supply via commands sent from the Main board. When AUTO GND is
floated (opened), it pulls up and places the Controller (IC701) into the Auto mode. In this state, the Controller turns on the floated (opened), it pulls up and places the Controller (IC701) into the Auto mode. In this state, the Controller turns on the
power supply in stages automatically. A load is necessary to perform a good test of the SMPS if the Main board is suspect.
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May 201 1 50PV450 Plasma