Start -up Section in SMPS
Start -up Section in SMPS:
Identification: In this section has one Start up Transistor with Heat Sink , Driver Transistor, Start up Transformaer, Opto Coupler IC, SBV wire attached this section.
Function: Start up section is provide Control IC Supply (5v to 24v) and Stand by Voltage at pin Number 9 (Voilet ) of ATX Power Connector.
Find Out:(Isolation):If Stand by Volatge present at Pin Number 9 of ATX Connector , it means this section is working . if no SBV present check Start up section.
Problem/ Solution
Problem 1 :Nil voltage at Pin No. 9 of power connector.
Solution – Check purple color wire may be open or dry shouldering, If wire ok
check +5v at output Pin of regulator I.C if nil output check supply 6 to 8 v and also check
ground if supply and ground both are ok but nil output from output Pin then replace I.C
Problem 2 - Nil voltage at supply Pin of regulator I.C.
Solution – First of all check .5 to 1.5 volt AC current at output rectifier diode if
voltage available mains primary side ok (start up Tr. and their spotting components all
are ok) and in condition disconnect output rectifier cathode terminal and again check
D.C voltage available diode ok output filter capacitor faulty.
Problem 3:Nil voltage at output rectifier diode anode terminal
Solution – Check start up primary side start up Tr. Collector -300v D.C Base -.2
to .8 and emitter should be ground if all biasing are ok of start up Tr. then completing
resold ring to start up Tr. and sporting component.
Problem 4- Nil voltage at start up Tr. Collector terminal.
Solution – Check 300v D.C at M.F.C. if voltage available mains line filter circuits
ok other wise check line filter circuit only series components. If required voltage at
M.F.C and nil voltage at collector mains low value fusible resistor is open.
Problem 5 - Nil voltage at base of start up Transistor.
Solution – Check kicking resistor may be open or dry soldering.
Problem 6 - More voltage available at base terminal of start up transistor –
Solution – check feedback component (resistor, capacitor, and diode) may be
open or dry soldering
Identification: In this section has one Start up Transistor with Heat Sink , Driver Transistor, Start up Transformaer, Opto Coupler IC, SBV wire attached this section.
Function: Start up section is provide Control IC Supply (5v to 24v) and Stand by Voltage at pin Number 9 (Voilet ) of ATX Power Connector.
Find Out:(Isolation):If Stand by Volatge present at Pin Number 9 of ATX Connector , it means this section is working . if no SBV present check Start up section.
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| Start up Section CKT 1 |
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| Start Up Section Using IC CKT 2 |
Problem/ Solution
Problem 1 :Nil voltage at Pin No. 9 of power connector.
Solution – Check purple color wire may be open or dry shouldering, If wire ok
check +5v at output Pin of regulator I.C if nil output check supply 6 to 8 v and also check
ground if supply and ground both are ok but nil output from output Pin then replace I.C
Problem 2 - Nil voltage at supply Pin of regulator I.C.
Solution – First of all check .5 to 1.5 volt AC current at output rectifier diode if
voltage available mains primary side ok (start up Tr. and their spotting components all
are ok) and in condition disconnect output rectifier cathode terminal and again check
D.C voltage available diode ok output filter capacitor faulty.
Problem 3:Nil voltage at output rectifier diode anode terminal
Solution – Check start up primary side start up Tr. Collector -300v D.C Base -.2
to .8 and emitter should be ground if all biasing are ok of start up Tr. then completing
resold ring to start up Tr. and sporting component.
Problem 4- Nil voltage at start up Tr. Collector terminal.
Solution – Check 300v D.C at M.F.C. if voltage available mains line filter circuits
ok other wise check line filter circuit only series components. If required voltage at
M.F.C and nil voltage at collector mains low value fusible resistor is open.
Problem 5 - Nil voltage at base of start up Transistor.
Solution – Check kicking resistor may be open or dry soldering.
Problem 6 - More voltage available at base terminal of start up transistor –
Solution – check feedback component (resistor, capacitor, and diode) may be
open or dry soldering
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