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Plasma Fall 2008 42PG20
Power Supply Operation and Troubleshooting
AC Voltage is supplied to the SMPS Board at Connector CN101 from the AC Input Filter. Standby 5V is developed
from 340V source supply (which during standby measures 159V hot ground). This supply is also used to generate all
other voltages on the SMPS.
The 5V (standby) voltage is routed to the Sub Micon circuit (IC701) on the SMPS and through P813 to the Main PWB
for Micon (IC100) operation. LD703 will glow green to indicate STBY 5V has arrived.
AC detect Pin 18, P813 is generated on the SMPS by monitoring the AC input and rectifying a small sample voltage.
This AC Detect Voltage is routed to (IC701) the Sub Micon on the SMPS and the Micon (IC100) located on the Main
Board and is used as a basic “SMPS OK” signal.
When the Micon (IC100) on the Main Board receives an “ ON “ Command from either the Keyboard or the Remote IR
Signal it outputs a high to RL-ON. This signal first turns on a DC level shifter Q706 which creates 5V General. LD703
now glows amber indicating 5V General has been generated. This 5V General now provides the pull up voltages when
supply the output circuits to the SMPS. The RL-ON enters the SMPS Board at Pin 19 of P813. The RL-ON Voltage is
sensed by the Sub Micon (IC701) circuit which causes the Relay Drive Circuit to close Relay RL101 bringing the PFC
source up to full power by increasing the 159V standby to 340V. At this time the 16V source becomes active and sent
to the Main Board via P813.
The next step is for the Micon (IC105) on the Main Board to output a high on M5V_ON Line to the SMPS at P813 Pin 21
which is sensed by the Sub Micon IC (IC701) on the SMPS turning on the 5V VCC line.
The last step to bring the supply to “Full Power” occurs when the Micon (IC100) on the Main Board brings the
VS-ON line high at Pin 20 of P813 on the SMPS Board which when sensed by the Sub Micon IC (IC701) turns
on the VA and VS Supplies (VA is brought high before VS).
Power Supply Basic Operation
Power Supply Basic Operation
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