Thursday, January 18, 2018

LG CM6520 Mini Hi-Fi System – Schematic – Power supply, RF servo, DSP - Main amp – SMPS Power supply troubleshooting

No power
Fuse & bridge diode
Check and replace F901, BD901, TH901, TH903 on SMPS board.
Check if the fuse F901 has open or short-circuit.
Check if the bridge diode BD901 has short-circuit by over current, with a multi meter.
Check if the NTC thermistor TH901 and TH902 is normal or open.
Click on the pictures to magnify
The unit doesn’t work, no power problem
Check the Anode-Cathode Voltage of D951 with a digital multi-meter, it is normally 0.2 ~ 0.3 V.   If it doesn’t have any voltage, it has been damaged.  Replace it with a new one.
Check if ZD951 is short-circuited.   
If it has short-circuit,  replace it with a new one.
Click on the schematics to magnifty.
Can take a magnified printout of these circit diagrams.
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SMPS Circuit diagram
DSP (Digital Signal Porocessing) schematic
Micro-controller (MICOM) schematic
PWM Schematic
Servo schematic
Main amplifier schematic