Hardware Troubleshooting : Smps; Fel-3237A : Dla-32/37C7Lmbd - Daewoo LCD TV Service Manual

7. Hardware Troubleshooting : SMPS

1) FEL-3237A : DLA-32/37C7LMDB
1. Stand-by 5V is working out.
A. Can you check In-put voltage(DC) of the capacitor(Location No. : C22)?
A. Can you check that Vcc voltage of IC3 was supplied from DC15V to DC27V?
YES 1.1 Checking open and short of Out-put side wire cable.
YES
1.2. Checking open and short of the around parts that was connected IC3(STR-A6151).
NO 1.3. Checking open and short of IC3's each pins.
1.4. Checking open and short of 5V's Out-put diode.
1.5. Can you check the Fuse(F1) condition(open and short)?
NO 1.6. Checking open and short of BD1, BD2.
2. MAIN Out-put voltage is working out but Stand-by 5V is working.
A. Can you check that it is working normal at Power On after dischanging for 1 minute from Power Off?
YES : It's protection due to out-put short of the moment through worker's carelessness.
NO : Checking 2.1 item.
A. Is Power On signal(3.3V) supplied to Base of Q4?
B. Can you check the Q4's condition(open and short)?
2.1. Can you check the D4's condition(open and short)?
2.2. Is Relay connected?
NO
2.3. Can check the voltage(AC 400V) of AC rectifying side C23?
YES 2.4. changing Q4.
YES
C. Can you check that Vcc voltage of IC2's No.12pin was supplied from DC10V to DC12V?
2.5. Can you see the square wave(400mV, 32kH) of Q2's source side when DC 13V
NO
YES 2.6. Checking open and short of MAIN BOARD.
NO 2.7. Checking open and short of MAIN BOARD.
'CHECKING FLOW ABOUT INFERIOR SMPS' (MODEL NAME : FEL-3237A)
(Location No. : R4, R5, D4, D5, D7)
(Location No. : D13)
YES : Checking 1.2 item after changing FUSE.
YES : Changing BD1, BD2.
NO : Checking open and short of Z1, LF1, LF2, C1, C2.
YES : Changing D4.
YES : Checking 2.3 item.
YES : Checking 2.5 item.
NO : Checking 2.5 item after checking the conditions(open and short) of the around
parts that was connected IC1. (Location No. : R14, R65, Q1, D1, D23, D12, IC1)
was supplied to IC2's No.12pin from DC POWER SUPPLY?
(CAUTION : Test do it after AC Power Off)
YES : Checking 2.1 item after checking diode's condition(open and short) of Main Out-put side.
(Location No. : D17, D18, D19, D16, D15, D14)
NO : Checking open and short of the around parts that was connected IC2.
(Location No. : Q2, Q3, D25, D26, D24, R31, R32, R35, R36, R38, D9, D10, C17)
NO : Checking 1.6 item.
NO : Checking 2.2 item.
NO : Changing Relay.
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